No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
MRI evidence that docosahexanoic acid ethyl ester improves myelination in generalized peroxisomal disorders
Abstract
We have found that docosahexaenoic acid (DHA; 22:6n-3), an important constituent of the CNS and retina, is dramatically decreased in patients with generalized peroxisomal disorders. Such a DHA deficiency could be pathogenic. Our aim was to test the possible beneficial effects of normalizing the DHA levels in these patients. The current report focuses on MRI changes during the treatment and reports follow-up evidence of myelin improvement in five peroxisomal disorder patients treated with DHA.
DHA ethyl ester (DHA-EE), about 90% pure, was used at daily oral doses of 100 to 600 mg. The treatment was monitored both clinically and biochemically, with periodic neurophysiologic and MRI examinations and repeated controls of liver tests and blood fatty acids by capillary column gas chromatography.
DHA-EE normalized the blood levels of DHA in a few weeks. The levels of very-long-chain fatty acids decreased in plasma and those of plasmalogens increased in erythrocytes. Visual and liver function improved. On MRI, a virtual normalization of the brain myelin images was found in the three youngest patients. A clear improvement was noticed in the other two.
The beneficial effects obtained indicate that DHA deficiency plays an important role in the pathogenesis of peroxisomal disease, probably in relation to myelinogenesis. Early initiation of DHA therapy is thus strongly recommended in patients with generalized peroxisomal disorders.
... Los resultados clínicos obtenidos con el tratamiento con DHA-EE han aparecido en diversas publicaciones [16][17][18][19][20][21] y se pueden resumir en tres tipos de efectos: sobre la función hepática, sobre la visión y sobre el desarrollo pondoestatural y psicomotor. En aquellos enfermos en quienes ha predominado el cuadro hepático y de afectación del desarrollo pondoestatural las mejorías han sido a veces espectaculares. ...
... La tabla II resume los cambios observados. De los 12 pacientes estudiados, en 6 se detectaba una clara escasez de mielina cerebral en relación con los patrones normales para la edad [20,21], siendo difícil discernir si ello se debía a un retraso en la mielinización, a una mielinogénesis defectuosa o dismielinización, o más bien a una desmielinización incipiente. Por ello preferimos emplear el término hipomielinización, de significado más general, en la tabla II. ...
... En los cuatro pacientes mayores de 4 años, los cambios eran más bien indicativos de desmielinización, encontrándose ésta en fase activa en una paciente de 5 años de edad (caso 10), como se evidenció en sendas zonas de captación del contraste endovenoso en lóbulos frontales (Fig. 5a). Aunque no tenemos una segunda RM de todos los pacientes, de aquellos en que sí hemos podido llevar a cabo un seguimiento, hemos observado un claro avance de la mielinización en 5 de ellos, llegando prácticamente a normalizarse en 3. En la paciente que estaba en fase de desmielinización activa antes del tratamiento (Fig. 5a) el proceso se detuvo, como pudimos observar en la segunda RM efectuada dos años más tarde (Fig. 5b), e incluso parecía iniciarse una remielinización [21]. En otros dos niños que habían comenzado el tratamiento bastante tarde, a los 15 y 16 meses de edad (casos 7 y 8) y en los que se apreciaban ya imágenes sugestivas de desmielinización (Figs. ...
... Several studies have explored the effect of supplementing DHA, due its important role in membrane integrity and because its levels are markedly reduced in tissues and plasma of PBD patients . [13,14,15,17] In this study 14 patients diagnosed as PBD and 7 patients diagnosed as adult ALD, were given DHA at a daily dose of 100-500 mg for nine months. They were 14 males and 7 females, which denote higher male affection, due to the X-linked recessive inheritance in adult ALD. ...
... These findings coincides with the findings of other studies . In general the clinical and [25,13,26,30] neurophysiological manifestations were severer in the patient with Zellweger syndrome than the rest of the ZSS patients. ...
... In MRI the myelin changes improved in 6 patients (Figs 1 & 2). Martinez and Vazquez followed up 5 patients with peroxisomal [13] disorders and mentioned that normalization of the brain myelin images was found in 3 patients and clear improvement was noticed in two other patients. Younger patients showed the best results with DHA therapy. ...
neurological diseases termed peroxisomal biogenesis disorders (PBD), where brain fatty acids homeostasis is disturbed. Being a major component of membrane phospholipids in brain and retina, docosahexaenoicacid (DHA) is profoundly reduced in tissues of patients with PBD. The aim of this work was to study the role of DHA supplementation in patients with peroxisomal biogenesis disorders. Also, to evaluate the effect of correcting DHA deficiency on the psychological development, vision, brain demyelination, liver and kidney functions. Subjects and methods: The study included 14 patients with PBD, 7 patients with adult adrenoleukodystrophy (ALD) and 11 controls. Their ages ranged from 9 months to 13 years. They were subjected to full clinical examination, pedigree analysis and biochemical investigations including: plasma very long chain fatty acids (VLCFAs) and DHA evaluation by GC/MS in addition to liver and kidney functions. Magnetic resonance imaging (MRI) examination of the brain, electroencephalogram
(EEG) and visual evoked potential (VEP) were done before and after DHA therapy. All individuals were treated with DHA, at daily doses of 100-500 mg, according to age of the child, for 9 months. Treatment had been accompanied by a nutritious diet, based on recommended dietary allowances (RDA) for age, in order to provide all necessary nutrients. Neuropsychological evaluation was done to assess five
psychological abilities (language, visual perception, memory, attention and construction abilities) before and after the therapy; and a global neuropsychological impairment score was developed. Results: PBD
patients showed improvement of vision, social contact, hypotonia and feeding difficulties. The developmental curve began to accelerate and the muscular tone improved. The VEP improved in 57.1% of PBD patients and normalized in 21.4%. The EEG improved in 71.4% and the MRI improved in 42.8% of PBD patients. After 9 months of DHA treatment, the plasma levels and ratios of VLCFAs decreased and the DHA levels increased in PBD patients. This change was statistically significant in NALD group.
On MRI examination, a remarkable improvement was noticed in the youngest patients with PBD. The effect of DHA therapy on liver and kidney functions was beneficial, but minimal among the PBD patients. Incontrast, patients with adult ALD showed no clinical, neurophysiological or neuropsychological improvement and little biochemical response to DHA therapy. Conclusion: The results suggest a fundamental role of DHA in amelioration of symptoms in patients with PBD, especially in the Zellweger syndrome spectrum patients. Therefore, early DHA therapy is highly recommended in peroxisomal biogenesis disorders.
... 8 MRI studies suggest reduced corpus callosum and superior long fasciculus mass in patients with ASD. 9 Omega 3 fatty acid contains essential docosahexaenoic acid and ecosapentanoic acid. Docosahexaenoic acid is highly concentrated in neuronal phospholipids, which is required for neurogenesis, neuronal survival, and neurotransmission. ...
... 18 A small double-blind randomized control trial showed reduced stereotypy and hyperactivity in children with ASD after 6 weeks of omega 3 therapy. 19 Open labeled studies have shown significant improvement in social awareness and attention after 12 weeks of supplementation [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] but no significant changes could be deduced from other blind trials. 21,22 Some case studies have reported improvement in the core symptoms of asd on supplementation for an extended period of time. ...
Autism is characterized by deficits in verbal and nonverbal communication and repetitive behaviors. There is a lack of data available regarding pharmacological treatment in autism spectrum disorders.
... Indeed, we found that liver lipids were highly accumulated in pex5 −/− compared to those in WT, while glycogen levels between the two genotypes were comparable (Fig. 1e, n = 6). ZSD also features defects in the nervous system, including demyelination [38,39]. Using transgenic zebrafish, Tg(mbp:EGFP), we found that pex5 −/− zebrafish at 20 dpf displayed severe demyelination (Fig. 1f, n = 6). ...
Animal models have been utilized to understand the pathogenesis of Zellweger spectrum disorders (ZSDs); however, the link between clinical manifestations and molecular pathways has not yet been clearly established. We generated peroxin 5 homozygous mutant zebrafish (pex5−/−) to gain insight into the molecular pathogenesis of peroxisome dysfunction. pex5−/− display hallmarks of ZSD in humans and die within one month after birth. Fasting rapidly depletes lipids and glycogen in pex5−/− livers and expedites their mortality. Mechanistically, deregulated mitochondria and mechanistic target of rapamycin (mTOR) signaling act together to induce metabolic alterations that deplete hepatic nutrients and accumulate damaged mitochondria. Accordingly, chemical interventions blocking either the mitochondrial function or mTOR complex 1 (mTORC1) or a combination of both improve the metabolic imbalance shown in the fasted pex5−/− livers and extend the survival of animals. In addition, the suppression of oxidative stress by N-acetyl L-cysteine (NAC) treatment rescued the apoptotic cell death and early mortality observed in pex5−/−. Furthermore, an autophagy activator effectively ameliorated the early mortality of fasted pex5−/−. These results suggest that fasting may be detrimental to patients with peroxisome dysfunction, and that modulating the mitochondria, mTORC1, autophagy activities, or oxidative stress may provide a therapeutic option to alleviate the symptoms of peroxisomal diseases associated with metabolic dysfunction.
... At repeated magnetic resonance imaging (MRI) made after treatment, the normalization of myelination of the brain was observed. Moreover, these positive changes in MRI were positively correlated with the improvement of patients' motor skills [34]. ...
Aim. To assess the neurological status and index of neuropsychological development in low birth weight children taking into account the FADS2 rs174583 (C/T) gene polymorphism.
Materials and methods. To study the FADS2 rs174583 (C/T) gene polymorphism, 170 children were examined. The children were divided into 3 groups depending on their birth weight: group I included 53 children (birth weight was 1500–1999 g, gestation period – 33.0 [32.0; 35.0] weeks), group II included 77 children (birth weight – 2000–2499 g, gestation period – 35.0 [34.0; 36.0] weeks), group III was composed of 40 children as a control (birth weight – more than 2500 g, gestation period – 38.0 [36.0; 39.0] weeks). The genotyping was carried out using a polymerase chain reaction method.
Results. The C allele and the С/Т genotype frequencies of the FADS2 rs174583 gene polymorphism in the children matched those in North-Western Europe. Seizures in the past medical history due to the nervous system disorders were most commonly occurred in children with the TT genotype (16.45 %, P < 0.05), while patients with the CC genotype had seizures in only 5.6 % of cases. Children with a birth weight of 1500–1999 g carrying the C/T heterozygous genotype and the T/T homozygous genotype of the FADS2 (rs1745683) gene polymorphism had a lower total Apgar score than children with a birth weight of more than 2000 g (P < 0.05). The coefficient of psychomotor development was the lowest in children with birth weight of 1500-1999 g and the minor homozygous T/T genotype of the FADS2 (rs1745683) gene polymorphism, at 83.0 (75.0; 83.0), which corresponded to a weak normal level of the neuropsychiatric development, while the highest index of psychomotor development (116.0 (112.0; 141.0)) and a normal high level of neuropsychiatric development were significantly registered in children with birth weight of 2500 g and the major homozygous C/C genotype.
Conclusions. It is possible that the predominance of the homozygous C/C genotype and the heterozygous C/T genotype fulfils a protective function in order to reduce the negative effects of preterm birth on the nervous system
... Cognitive, behavioural and psychological functions are assessed mainly by psychometric testing, such as computerised batteries of tests (tasks and cognitive skills), the Bayley Scales and normative scores like intelligence quotient (IQ) amongst few other methods ( Ryan and Nelson 2008;Politi et al. 2008;Kennedy et al. 2009;Sun et al. 2015). Neural brain functions are frequently assessed, amongst many other valid techniques, by biochemical, molecular and imagining techniques as well as neurodegenerative and neuromotor activity assessments such as Alzheimer's Disease Assessment Scale ( Martinez and Vazquez 1998;Wurtman et al. 2009;Quinn et al. 2010;Bauer et al. 2014). These methods of assessment have been widely used, standardised and referenced in scientific articles related to brain functions. ...
FSANZ has conducted a systematic review on dietary deficiency of DHA and the maintenance of normal brain and vision functions. In doing this review, FSANZ has followed the requirements of the Application Handbook and of Schedule 6 of Standard 1.2.7 – Nutrition, Health and Related Claims, for the required elements of a systematic review.
FSANZ identified five case studies in which seriously ill patients received DHA. However, none of these studies assessed any aspect of brain or vision functions after the intervention.
Due to the lack of suitable human studies of DHA and maintenance of normal brain and vision functions, FSANZ regards the two relationships that are the subject of this review as being ‘non-assessable’.
... Five PBD patients described as "Zellweger variants" showed improved vision and psychomotor development after treatment with DHA. In a later study by Martinez and Vazquez, 45 an improvement in magnetic resonance imaging scan was found in 5 PBD patients given DHA therapy. Martinez 44 also reported that DHA therapy leads to increased concentrations of plasmalogens and a reduction in the concentrations of VL-CFAs. ...
Inherited aberrant peroxisome assembly results in a group of neurological diseases termed peroxisome biogenesis disorders (PBDs). PBDs include three major clinical phenotypes that represent a continuum of clinical features from the most severe form, Zellweger syndrome (ZS), through neonatal adrenoleukodystrophy (NALD) to the least severe form, infantile Refsum's disease (IRD). Somatic cell complementation studies have identified 13 PBD complementation groups, each representing a defect in a peroxisomal protein (peroxin) involved in peroxisome biogenesis. Most complementation groups include a range of clinical phenotypes. In this study, peroxisome numbers were determined in fibroblasts from 29 PBD (ZS, NALD, and IRD) patients, with various phenotypes from nine complementation groups, using antibodies against either a peroxisomal membrane protein (anti-Pex14p) or peroxisomal matrix proteins (anti-SKL). A correlation between the number of peroxisomes, determined with either antibody, and PBD phenotype was found, suggesting that induction of peroxisome number might have a favorable effect on PBD. After treatment of PBD fibroblasts with sodium 4-phenylbutyrate, a human peroxisome proliferator, there was an approximate twofold increase in peroxisome number. After 4-phenylbutyrate treatment, an increase in transcription of the adrenoleukodystrophy-related gene and the peroxin gene, PEX11α, was found in PBD fibroblasts. In NALD and IRD, but not ZS, fibroblasts there was an increase in very-long-chain fatty acid β-oxidation and plasmalogen concentrations, and a decrease in very-long-chain fatty acid concentrations. These data suggest that pharmacological agents that induce peroxisome proliferation, such as 4-phenylbutyrate, may have therapeutic potential in the treatment of PBD patients with milder phenotypes (NALD and IRD). Ann Neurol 2000;47:286–296
... Zellweger syndrome results in a dysfunction in fatty acid oxidation that contributes to an accumulation of fatty acids, a decrease in plasmalogen levels, and hypomyelination (Ferdinandusse et al. 2001;Weller et al. 2003;Chrast et al. 2011;Poll-The and Gartner 2012). Docosahexaenoic acid supplementation improves neuronal function related to vision and muscle movement in young children and infants (Martinez et al. 1993(Martinez et al. , 2000Martinez 1996Martinez , 2001, returns plasma docosahexaenoic acid and plasmalogen to normal (Martinez et al. 2000), and improves myelination as shown in MRI scans of patients given DHA supplementation (Martinez and Vazquez 1998;Martinez et al. 2000). Interestingly, for DHA supplementation to be effective, patients need to be treated early in development (Martinez et al. 2000;Martinez 2001) suggesting that the disruption in lipid metabolism, similar to that found in this study, must be addressed prior to the loss of cellular function to be effective. ...
Acetate supplementation increases brain acetyl‐CoA metabolism, alters histone and non‐histone protein acetylation, increases brain energy reserves, and is anti‐inflammatory and neuroprotective in rat models of neuroinflammation and neuroborreliosis. To determine the impact acetate supplementation has on a mouse model of multiple sclerosis, we quantified the effect treatment had on injury progression, spinal cord lipid content, phospholipase levels, and myelin structure in mice subjected to experimental autoimmune encephalomyelitis ( EAE ). EAE was induced by inoculating mice with a myelin oligodendrocyte glycoprotein peptide fragment ( MOG 35–55 ), and acetate supplementation was maintained with 4 g/kg glyceryl triacetate by a daily oral gavage. Acetate supplementation prevented the onset of clinical signs in mice subject to EAE compared to control‐treated mice. Furthermore, acetate supplementation prevented the loss of spinal cord ethanolamine and choline glycerophospholipid and phosphatidylserine in mice subjected to EAE compared to EAE animals treated with water. Treatment increased saturated and monounsaturated fatty acid levels in phosphatidylserine compared to controls suggesting that acetate was utilized to increase spinal cord fatty acid content. Also, acetate supplementation prevented the loss of spinal cord cholesterol in EAE animals but did not change cholesteryl esters. Treatment significantly increased GD 3 and GD 1a ganglioside levels in EAE mice when compared to EAE mice treated with water. Treatment returned levels of phosphorylated and non‐phosphorylated cytosolic phospholipase A 2 ( cPLA 2 ) levels back to baseline and based on FluoroMyelin™ histochemistry maintained myelin structural characteristics. Overall, these data suggest that acetate supplementation may modulate lipid metabolism in mice subjected to EAE .
image
... 27,28 Some of the first evidence that supplemental omega-3 PUFAs may improve brain structure in humans came from a study in which DHA was administered to five peroxisomal disorder patients. 29 This study found that treatment with DHA normalized or significantly improved brain white matter on MRI imaging. ...
Brain structure can be shaped and remodeled by several important environmental factors throughout an individual's life course, with nutrition and chronic stress two of the most established environmental factors. Stress-induced atrophy in key brain regions is thought to play a central role in the development of mental health disorders including depression, psychosis, and cognitive decline. Conversely, nutrients, in particular the omega-3 fatty acids and homocysteine-lowering B vitamins, can improve mental health and are potent modulators of brain structure with evidence suggesting that personalized nutritional interventions may increase neurogenesis, restore brain structure and protect the brain from the damaging e!ects of stress. Furthermore, nutritional interventions may augment and improve the potential for behavioral therapies and lifestyle changes to reverse brain atrophy and, in turn, improve mental and physical wellbeing.
... An intriguing possibility suggested by the recent work of Peters and colleagues [92] is that individuals with fatty acid desaturases (FADS) minor alleles have poorer quality brain white matter development, which affects brain function. Martinez and Vazquez [93] first showed a link between brain DHA accumulation and myelination in children with peroxisomal disorders who are unable to synthesize DHA, so differences in LCPUFA synthesis could theoretically decrease brain myelination. Limitations in LCPUFA synthesis could thus indirectly affect brain myelination. ...
... The peak of the omega-3 accumulation rate in the nervous system coincides with the neurodevelopmental onset of myelination (McNamara and Carlson, 2006), and DHA has been reported to normalize myelin in humans who suffer from the demyelination caused by generalized peroxisomal disorders (Martinez and Vazquez, 1998). Peroxisomes are necessary for the production of DHA from its precursors (Lizard et al., 2012). ...
... Essential PUFAs cannot be synthesized de novo, but are important components of cell membranes. Notably, DHA may play a role in decreased brain injury (11,12) and improved development (13)(14)(15). In addition, the ω-6 PUFA arachidonic acid (ARA) is a precursor to hormones that regulate inflammation, including prostaglandins and leukotrienes, with additional potential effects. ...
Background:
Preterm birth has a dramatic impact on polyunsaturated fatty acid exposures for the developing brain. This study examined the association between postnatal fatty acid levels and measures of brain injury and development, as well as outcomes.
Methods:
A cohort of 60 preterm newborns (24-32 weeks GA) was assessed using early and near-term MRI studies. Red blood cell fatty acid composition was analyzed coordinated with each scan. Outcome at a mean of 33 months corrected age was assessed using the Bayley Scales of Infant Development, 3(rd) edition.
Results:
Adjusting for confounders, a 1% increase in postnatal docosahexaenoic acid (DHA) levels at early MRI was associated with 4.3-fold decreased odds of intraventricular hemorrhage, but was not associated with white matter injury or cerebellar haemorrhage. Higher DHA and lower linoleic acid (LA) levels at early MRI were associated with lower diffusivity in white matter tracts, and corresponding improved developmental scores in follow-up.
Conclusion:
Higher DHA and lower LA levels in the first few weeks of life are associated with decreased IVH, improved microstructural brain development, and improved outcomes in preterm born children. Early, and possibly antenatal, intervention in high-risk pregnancies needs to be studied for potential benefits in preterm developmental outcomes.Pediatric Research (2016); doi:10.1038/pr.2016.11.
... Furthermore, intervention studies have found that postnatal dietary DHA supplementation improves visual attention processes in preterm infants (Carlson and Werkman, 1996). Pediatric patients with generalized peroxisomal disorders exhibit significant RBC and postmortem cortex DHA deficits (Martinez et al., 1995) and impaired myelinogenesis (Powers & Moser, 1998), and a preliminary structural MRI study found that treatment with DHA ethyl ester normalized or significantly increased brain white matter volumes in pediatric peroxisomal disorder patients (Martinez & Vazquez, 1998). However, a placebo-controlled structural MRI study found that postnatal DHA supplementation did not significantly alter age-related changes in white matter volume in premature infants (van Wezel-Meijler et al., 2002). ...
Addiction is usually defined as the continued use of substances or activities despite their negative consequences. Different models have been proposed to explain why people start using drugs and why they still continue using even when they experience physical, psychological and/or social problems. In this context, prefrontal cortex (PFC), which has been involved in complex cognitive functions such as abstract thinking, planning, inhibitory control or decision-making, has gained much of the attention when explaining addiction due to its implication in different aspects related to addictives behaviours. In this chapter, we will focus on the PFC and its involvement in the addictives processes, paying particular attention to the somatic marker hypothesis. According to this model, substance abusers as well as patients with ventromedial prefrontal cortex (VMPC) lesions, show altered decision-making, characterized by a tendency to choose the immediate reward and by not taking into account long-term consequences of their behaviour. Growing scientific evidence indicates that core aspects of addiction may be explained in terms of an abnormal decision-making. The aim of this chapter is to review the previous literature regarding the role of the PFC in this process and, therefore, in the addictive behaviour. After describing the anatomy and functions of the PFC, different models and definitions of addiction will be discussed. Then, we will focus on the somatic marker model, which establishes that the altered decision-making in addiction is a consequence of an abnormal functioning of a distributed neural network critical for the processing of emotional information involving several regions of the PFC and limbic system. Accordingly, an examination of the scientific evidences that support the role of PFC in addiction will be conducted. Finally, we will discuss the implications for addiction treatment and prevention.
... DHA is also an essential regulator of brain myelination. DHA supplementation has been successfully used to normalize magnetic resonance images (MRI) of brain myelination in childhood peroxisomal disorders [27]. DHA and AA are also important modulators of signal transduction and gene expression. ...
Objective:
Fatty acids are critical for pediatric neurodevelopment and are abnormal in autism, although prior studies have demonstrated conflicting results and methodological differences. To our knowledge, there are no published data on fatty acid in Canadian children with autism. The aim of this study was to investigate red blood cell and serum fatty acid status to identify whether abnormalities exist in Canadian children with autism, and to enhance future cross-study comparison.
Methods:
Eleven Canadian children with autism (3 girls, 8 boys; age 3.05 ± 0.79 y) and 15 controls (9 girls, 6 boys; age 3.87 ± 1.06 y) met inclusion criteria, which included prior Diagnostic and Statistical Manual diagnosis of autism spectrum disorder, no recent medication or supplements, no specialty diets, and no recent illness.
Results:
The children with autism demonstrated lower red blood cell docosahexaenoic acid (P < 0.0003), eicosapentaenoic acid (P < 0.03), arachidonic acid (P < 0.002), and ω-3/ω-6 ratios (P < 0.001). They also demonstrated lower serum docosahexaenoic acid (P < 0.02), arachidonic acid (P < 0.05), and linoleic acid (P < 0.02) levels.
Conclusions:
Fatty acids in both serum and red blood cells were abnormal in this small group of Canadian children with autism than in controls, underlining a need for larger age- and sex-matched investigations in this community. A potential role for fatty acid abnormalities within the complex epigenetic etiology of autism is proposed in relation to emerging understanding of relationships between cobalamin metabolism, gut microbiota, and propionic acid production.
... Moreover, deficits in cortical DHA concentrations in preterm baboons were not fully restored to control levels following 4 wk feeding formula fortified with a moderate dose of DHA (0.61%) [106] . It is also relevant that a placebo-controlled structural MRI study found that feeding formula containing lower levels of DHA (0.34%) did not significantly alter white matter volume in premature infants [177] , whereas a preliminary intervention study observed improvements in brain white matter volumes in neonates with peroxisomal disorders following supplementation with higher DHA doses (100-600 mg/d) [178] . These and other findings have led to new recommendations for higher dose DHA supplementation for preterm infants to improve neurological and cognitive outcomes [179] . ...
Accumulating translational evidence suggests that the long-chain omega-3 fatty acid docosahexaenoic acid (DHA) plays a role in the maturation and stability of cortical circuits that are impaired in different recurrent psychiatric disorders. Specifically, rodent and cell culture studies find that DHA preferentially accumulates in synaptic and growth cone membranes and promotes neurite outgrowth, dendritic spine stability, and synaptogenesis. Additional evidence suggests that DHA may play a role in microglia-mediated synaptic pruning, as well as myelin development and resilience. In non-human primates n-3 fatty acid insufficiency during perinatal development leads to widespread deficits in functional connectivity in adult frontal cortical networks compared to primates raised on DHA-fortified diet. Preterm delivery in non-human primates and humans is associated with early deficits in cortical DHA accrual. Human preterm birth is associated with long-standing deficits in myelin integrity and cortical circuit connectivity and increased risk for attention deficit/hyperactivity disorder (ADHD), mood, and psychotic disorders. In general, ADHD and mood and psychotic disorders initially emerge during rapid periods of cortical circuit maturation and are characterized by DHA deficits, myelin pathology, and impaired cortical circuit connectivity. Together these associations suggest that early and uncorrected deficits in fetal brain DHA accrual may represent a modifiable risk factor for cortical circuit maturation deficits in psychiatric disorders, and could therefore have significant implications for informing early intervention and prevention strategies.
... Moreover, the downregulation of the peroxisomal VLCFA -oxidation may lead to a decrease of docosahexaenoic acid (DHA) synthesis. DHA is not directly incorporated in myelin sheets, but its presence is crucial for OL maturation and the formation of mature myelin (Martinez, 1998). Very recently, it has been demonstrated that DHA is a ligand for RXR (Mata de Urquiza et al., 2000), the heterodimeric partner of many nuclear receptors, including PPARs, thyroid hormone , and retinoic acid. ...
The original article to which this Erratum refers was published in GLIA (2003)41:3–14
... Many ZS patients have lower plasma docosahexaenoic acid (DHA), a fatty acid that plays an important role in brain development and function that requires peroxisomal β-oxidation for its synthesis (13,14). It has been shown that oral DHA therapy can normalize blood DHA levels, but its effect on clinical outcome has not yet been proven (15,16). Oral bile acid administration has been shown to improve hepatobiliary function in several infants with ZS (17,18). ...
Abstract We present a 2-month-old male affected by Zellweger syndrome, a rare peroxisomal disorder. The diagnosis was supported by clinical and radiological findings and established by biochemical tests. The characteristic radiological features included anomalous ossification (epiphyseal stippling). We also discuss main differential diagnoses of epiphyseal stippling and a brief literature review.
... In 1972 Crawford and Sinclair first published evidence that DHA itself, was an independent determinant of brain growth and evolution 1 (Broadhurst el al. 2002). Deficiency studies in rodents (Sinclair and Crawford 1972; Benolken et al. 1973; Galli and Socini 1983; Weisinger et al. 1999; Catalan et al. 2002), chickens (Budowski et al. 1987), primates (Fiennes et al. 1973; Neuringer et al. 1986) and visual and cognitive trials in human infants (Carlson and Werkman 1996; Martinez and Vazquex 1998; Birch et al. 2000) have indicated that DHA is essential to brain development and function . Moreover, collaboration with the Hebrew University of Jerusalem (HUJ) we described competition existing between ω6/ω3 fatty acids and showed that their balance is critical for brain development and structural integrity (Budowski and Crawford 1985). ...
Lipids played a major, as yet unrecognised, role as determinants in evolution. Life originated 3 billion years ago during which time there was ample opportunity for DNA modification. Yet there was little change in the life forms for the first 2.5 billion years. It was not until about 600 million years ago when the oxygen tension rose to a point where air breathing life forms became thermodynamically possible, that a major change is seen in the fossil record. The sudden appearance of the 32 phyla in the Cambrian fossil record which flowed from this environmental change is referred to as the "Cambrian Explosion". It was also associated with the appearance of intracellular detail and cell differentiation. That detail was provided by cell membranes in which the lipids were structural essentials. Thus not just oxygen but also the lipids were drivers in the Cambrian explosion. Docosahexaenoic acid (DHA) provided the basic membrane backbone of the new photoreceptors that converted photons into elec-tricity laying the foundation for the evolution of the nervous system and the brain. Although there are two closely related fatty acids with only one double bond different DHA was not replaced despite some 600 million years of genomic change. Whilst the marine food chain is rich in long chain omega 3 fatty acids, the land food web is dominated by omega 6 fatty acids. With the brain utilising omega 6 and 3 fatty acids in a ratio of between 1 to 1 and 2 to 1 the injection of the omega 6 through the 58 M. A. CRAWFORD et al. appearance of omega 6 rich protected seeds in the Cretaceous Period, would have played a critical role in the advance of brain evolution. This symbiosis between land and marine food chains, most likely created the condition that finally led to the cer-ebral expansion in human evolution. Lipids are still modifying the present evolution-ary phase of our species with their contribution to a changing panorama of non com-municable disease. The contemporary lipid malnutrition is most likely contributing to the rise in brain disorders which in the European Union has overtaken the cost of all other burdens if ill health at 386 billion for the 25 member states at 2004 price.
... As AA recycling is unchanged and DPA is elevated, it is likely that n-3 de®ciency shifts the competitive balance between n-3 and n-6 species toward favoring the n-6 species. In humans, it is becoming increasingly evident that altering the n-3/n-6 proportion is a mediator of harmful in¯ammatory, thrombotic and arrhythmic events mediated by eicosanoids (Okuyama et al. 1997;Lands 2000), and a critical variable in certain neurological disorders (Martinez and Vazquez 1998;Freedman et al. 1999;Stoll et al. 1999) and for changes in memory and learning-related behavior in rats (Bourre et al. 1989;Enslen et al. 1991;Greiner et al. 1999Greiner et al. , 2001. We do not know, at this time, if DPA, like DHA, can modulate eicosanoid production (Matsumoto et al. 1993;Reinboth et al. 1996). ...
Using an in vivo fatty acid model and operational equations, we reported that esterified and unesterified concentrations of docosahexaenoic acid (DHA, 22 : 6 n-3) were markedly reduced in brains of third-generation (F3) rats nutritionally deprived of α-linolenic acid (18 : 3 n-3), and that DHA turnover within phospholipids was reduced as well. The concentration of docosapentaenoic acid (DPA, 22 : 5 n-6), an arachidonic acid (AA, 20 : 4 n-6) elongation/desaturation product, was barely detectable in control rats but was elevated in the deprived rats. In the present study, we used the same in vivo model, involving the intravenous infusion of radiolabeled AA to demonstrate that concentrations of unesterified and esterified AA, and turnover of AA within phospholipids, were not altered in brains of awake F3-generation n-3-deficient rats, compared with control concentrations. Brain DPA-CoA could be measured in the deprived but not control rats, and AA-CoA was elevated in the deprived animals. These results indicated that AA and DHA are recycled within brain phospholipids independently of each other, suggesting that recycling is regulated independently by AA- and DHA-selective enzymes, respectively. Competition among n-3 and n-6 fatty acids within brain probably does not occur at the level of recycling, but at levels of elongation and desaturation (hence greater production of DPA during n-3 deprivation), or conversion to bioactive eicosanoids and other metabolites.
... However, prospective structural MRI is ideally suited to evaluate this relationship. For example, patients with generalized peroxisomal disorders exhibit significant erythrocyte and postmortem cortex DHA deficits [150] and impaired central myelinogenesis [151], and a preliminary structural MRI study found that treatment with DHA ethyl ester (100-600 mg/d) normalized or significantly improved brain white matter volumes in peroxisomal disorder patients [152]. A second preliminary structural MRI study found that greater habitual intake of long-chain omega-3 fatty acids, which are positively correlated with erythrocyte DHA composition [108][109][110][111], was associated with larger gray matter volumes in the anterior cingulate cortex, the right hippocampus, and the right amygdala [153]. ...
Background:
Piracetam is the most widely used drug in breath-holding spells (BHS); however, its efficacy might not be satisfying to parents. This study aimed to compare the efficacy of docosahexaenoic acid (DHA) plus piracetam with piracetam alone in reducing the frequency and severity of BHS in infants and preschool children.
Methods:
This randomized clinical trial included two groups diagnosed with BHS. Group I included 50 patients who received DHA plus piracetam. Group II (control group) included 50 children who were managed with piracetam plus a placebo. Children were re-evaluated at one, three, and six months after treatment. Occurrences of BHS and drug side effects were recorded. The primary outcome was to evaluate the effect of the combined treatment of piracetam and DHA on the frequency and severity of spells.
Results:
BHS were reported in only 16% of children six months after treatment with piracetam and DHA compared with 50% of those treated with piracetam only (P value = 0.001).
Conclusion:
DHA plus piracetam is more effective than piracetam alone in decreasing the frequency and severity of BHS in children.
Degenerative disorders of the newborn are relatively rare. Nonetheless, they are important to recognize because a few are treatable when diagnosed early. Dividing these disorders into those that primarily affect gray matter, white matter, or both is useful. Disorders of gray matter are characterized by seizures, myoclonus, spikes, or sharp activity on electroencephalogram, failure of cognitive development, and retinal disease. Some are accompanied by visceral storage including GM1 gangliosidosis, GM2 gangliosidosis, Niemann-Pick disease, Gaucher disease, Farber disease, and infantile sialic acid storage disease. Other gray matter disorders such as Tay-Sachs disease, congenital neuronal ceroid-lipofuscinosis, Alpers disease, and Menkes disease lack visceral storage. White matter disorders are characterized by marked motor deficits and slow activity on electroencephalogram and include Canavan disease, Alexander disease, Krabbe disease, Pelizaeus-Merzbacher disease, and Aicardi-Goutieres disease. Disorders that affect both white and gray matter often target subcellular structures (mitochondria, peroxisomes), target amino acid or neurotransmitter synthesis pathways, and can have regional selectivity for the cerebellum, pons, or basal ganglia. Examples include neonatal adrenoleukodystrophy, Zellweger syndrome, Leigh syndrome, mitochondrial encephalopathies, congenital disorders of glycosylation, pontocerebellar hypoplasias, neurotransmitter defects including serine synthesis deficiency, and Rett syndrome in males. We discuss each of these disorders briefly, focusing on clinical features, diagnosis, genetics, neuropathology, neuroimaging findings, current treatments, and emerging therapies.
Peroxisomes play a central role in the biosynthesis of polyunsaturated fatty acids including docosahexaenoic acid (C22:6 (n-3)) since the last step in the pathway from C24:6 (n-3) to C22:6 (n-3) does not involve a presumed δ-desaturase but is in fact catalyzed by the peroxisomal beta-oxidation system. As a consequence, formation of DHA is impaired in several of the peroxisomal disorders, notably the Zellweger spectrum disorders. A logical consequence of a defect in peroxisome biogenesis is the impaired peroxisomal beta-oxidation of fatty acids. DHA synthesis is also impaired in some of the single peroxisomal enzyme deficiencies including acyl-CoA oxidase deficiency and D-bifunctional protein deficiency. Supplementation of DHA to patients has been claimed to alleviate several of the clinical signs and symptoms of these patients. Recently, however, the results of a large placebo controlled double-blind study have been published, which shed doubt on the earlier claim that DHA supplementation to patients is indeed beneficial.
Improvements in the understanding of the biochemical and molecular basis of inborn errors have led to significant improvements in our ability to treat many of these disorders. Such improvements, coupled with an ability to make more rapid diagnoses and advances in general medical care, particularly intensive care, are resulting in better long-term prognosis for many patients. However, the rarity of individual disorders has often made it difficult or impossible to obtain sufficient data for evidence-based assessment of treatments. This should be kept in mind when considering the efficacy of particular therapies. Anecdotal reports of improvements should be reviewed critically, but it is equally important to remain open to new advances. This chapter discusses recent progress in the development of treatments. We have also included a list of medications (with recommended dosages) that may be used in the treatment of inborn errors (Table 5.1). Readers should refer to the relevant chapters for detailed information about the management of specific disorders and to Chap. 4, “Psychosocial Care of the Child and Family”, for discussion of the psychological consequences of treatment.
Peroxisomes are highly complex organelles, present in all mammalian cells except mature erythrocytes. They participate in amultitude of essential catabolic and biosynthetic functions, including β-oxidation of very long chain fatty acids (VLCFA), fatty acid α-oxidation, formation of plasmalogens, bile acids, polyunsaturated fatty acids (PUFA), cholesterol and leukotrienes, glyoxylate detoxification, and metabolism of H2O 2 (Purdue and Lazarow 2001). The process whereby peroxisomal membranes are assembled and peroxisomal matrix proteins are targeted from the cytosol and then imported into the organelle is a highly complex mechanism dependent on a series of specialized proteins termed "peroxins," encoded by more than one PEX gene. Mutations in PEX genes are responsible for peroxiosmal biogenesis disorders (PBD), characterized by absence of morphologically identifiable peroxisomes and loss of multiple or generalized peroxisomal functions. Another category of peroxisomal disorders includes disorders with a single peroxisomal enzyme or protein defect, with intact peroxisomes and preservation of other peroxiosmal functions.
Objective:
Although extant preclinical evidence suggests that the long-chain omega-3 fatty acid docosahexaenoic acid (DHA) is important for neurodevelopment, little is known about its role in human cortical structural and functional maturation. In the present cross-sectional study, we investigated the relationship between DHA biostatus and functional connectivity in cortical attention networks of typically developing children.
Methods:
Male children (aged 8-10 years, n = 36) were divided into 'low-DHA' (n = 18) and 'high-DHA' (n = 18) biostatus groups by a median split of erythrocyte DHA levels. Event-related functional connectivity during the performance of a sustained attention task (identical pairs continuous performance task (CPT-IP)) was conducted using functional magnetic resonance imaging. A voxelwise approach used the anterior cingulate cortex (ACC) as the seed-region.
Results:
Erythrocyte DHA composition in the low-DHA group (2.6 ± 0.9%) was significantly lower than the high-DHA group (4.1 ± 1.1%, P ≤ 0.0001). Fish intake frequency was greater in the high-DHA group (P = 0.003) and was positively correlated with DHA levels among all subjects. The low-DHA group exhibited reduced functional connectivity between the ACC and the ventrolateral prefrontal cortex, insula, precuneus, superior parietal lobule, middle occipital gyrus, inferior temporal gyrus, and lingual gyrus compared with the high-DHA group (P < 0.05; corrected). The low-DHA group did not exhibit greater ACC functional connectivity with any region compared with the high-DHA group. On the CPT-IP task, the low-DHA group had slower reaction time (P = 0.03) which was inversely correlated with erythrocyte DHA among all subjects.
Discussion:
These data suggest that low-DHA biostatus is associated with reduced event-related functional connectivity in cortical attention networks of typically developing children.
Evolution of the high order brain function in humans can be attributed to intake of poly unsaturated fatty acids (PUFAs) of which the ω-3 fatty acid, docosahexaenoic acid (DHA) has special significance. DHA is abundantly present in the human brain and is an essential requirement in every step of brain development like neural cell proliferation, migration, differentiation, synaptogenesis etc. The multiple double bonds and unique structure allow DHA to impart special membrane characteristics for effective cell signaling. Evidences indicate that DHA accumulate in areas of the brain associated with learning and memory. Many development disorders like dyslexia, autism spectrum disorder, attention deficit hyperactivity disorder, schizophrenia etc. are causally related to decreased level of DHA. The review discusses the various reports of DHA in these areas for a better understanding of the role of DHA in overall brain development. Studies involving laboratory animals and clinical findings in cases as well as during trials have been taken into consideration. Additionally the currently available dietary source of DHA for supplementation as nutraceutics with general caution for overuse has been examined.
Copyright © 2015. Published by Elsevier Ltd.
Although individual disease entities may not be frequently encountered in the practice of general radiology, the group of (known and yet unidentified or poorly defined) neurometabolic disorders accounts for a considerable percentage of central nervous system (CNS) pathologies seen, especially in the pediatric population. The prevalence of metabolic diseases is increasingly recognized as being actually higher than previously believed. Furthermore, since most of the metabolic diseases are genetically determined and show autosomal recessive inheritance, in communities where consanguinity is high (i.e., Amish families in Pennsylvania, some Jewish communities, North-American Indian and Saudi tribes, etc.), certain otherwise rare or even exceptional inborn errors of metabolism may be quite common. Indeed, metabolic diseases often exhibit specific ethnic or geographical preponderance, but epidemiological studies indicate that many of them are pan-ethnic and may occur sporadically anywhere [1]–[9].
Long-chain omega-3 (n - 3) fatty acids including docosahexaenoic acid (DHA) have anti-inflammatory, neurotrophic and neuroprotective properties. DHA accumulates in the brain during critical periods of perinatal cortical expansion and maturation. Reductions in perinatal rat brain DHA accrual are associated with delays in neuronal migration and arborization, synaptic pathology as well as neurocognitive deficits and elevated behavioural indices of aggression and depression. Primates raised on an n - 3 fatty acid-deficient diet exhibit hyperactivity, impairments in visual attention and functional connectivity deficits within frontal cortical networks. Preterm delivery is associated with robust deficits in fetal cortical DHA accrual and reduced connectivity within cortical networks. Children and adolescents born preterm are at increased risk for developing psychiatric disorders associated with functional connectivity deficits within frontal cortical networks. Moreover, youth with cognitive and mood disorders exhibit reversible DHA deficits associated with symptom severity. Maternal and infant formula DHA supplementation may be associated with better neurocognitive outcomes in healthy developing children though this remains controversial. While these associations provide general support for a role of DHA in the maturation of cortical networks mediating cognitive and emotional processes, additional prospective longitudinal studies are needed to inform optimal intake levels during critical periods of neurodevelopment.
Major psychiatric disorders including unipolar and bipolar depression, schizophrenia, and attention deficit hyperactivity disorder share cognitive impairments associated with deficits prefrontal cortex (PFC) structure and function. These disorders commonly initially emerge during adolescence, a period associated with rapid and dynamic changes in PFC structural maturation. Increasing evidence also suggests that each of these psychiatric disorders are associated with a deficiency in long-chain omega-3 (LCn-3) fatty acids, including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), which are evident proximal to illness onset. Preclinical studies have demonstrated LCn-3 fatty acids and their bioactive lipid metabolites have central neurotrophic, ant-inflammatory, and neuroprotective properties, and that reducing cortical DHA accrual during perinatal development leads to enduring deficits in PFC biochemistry and function. Preliminary human neuroimaging studies also suggest that LCn-3 fatty acid status is positively associated with cortical structural and functional integrity. Together, this body of translational evidence supports the proposition that low LCn-3 fatty acid status during active periods of PFC maturation may represent a modifiable pathogenic mechanism leading to deficits in PFC structure and function associated with psychopathology.
Abstract Erken, Haydar Ali, Gülten Erken, Ridvan Çolak, Osman Genç. Exercise and DHA prevent the negative effects of hypoxia on EEG and nerve conduction velocity. High Alt Med Biol 14:360-366, 2013.-It is known that hypoxia has a negative effect on nervous system functions, but exercise and DHA (docosahexaenoic acid) have positive effect. In this study, it was investigated whether exercise and/or DHA can prevent the effects of hypoxia on EEG and nerve conduction velocity (NCV). 35 adult Wistar albino male rats were divided into five groups (n=7): control (C), hypoxia (H), hypoxia and exercise (HE), hypoxia and DHA (HD), and hypoxia and exercise and DHA (HED) groups. During the 28-day hypoxia exposure, the HE and HED groups of rats were exercised (0% incline, 30 m/min speed, 20 min/day, 5 days a week). In addition, DHA (36 mg/kg/day) was given by oral gavage to rats in the HD and HED groups. While EEG records were taken before and after the experimental period, NCV records were taken after the experimental period from anesthetized rats. Data were analyzed by paired t-test, one-way ANOVA, and post hoc Tukey test. In this study, it was shown that exposure to hypoxia decreased theta activity and NCV, but exercise and DHA reduced the delta activity, while theta, alpha, beta activities, and NCV were increased. These results have shown that the effects of hypoxia exposure on EEG and NCV can be prevented by exercise and/or DHA.
Background: Obesity is a major susceptibility factor leading to the development of various conditions of the metabolic syndrome. In obese rats, slowing of motor nerve conduction velocity was observed. Fatty acids metabolism disturbance is very important in the occurrence of peripheral neuropathy. The aim of this work is to consider the role that balanced diets high in omega 6&9 PUFA (corn oil) or supplying rats with omega 3, play in modulating the impaired nerve function in obese rats. Methods: Thirty two adult male albino rats were randomly assigned to receive normal chow (NC) (n=8) or high fat diet HFD (n=24), for 12 weeks. After 12 weeks, body weight and body mass index(BMI) were measured and the NC group(n=8) continue their normal chow diet, Group 1 (NC) and served as a control group and the obese rats were randomly divided into 3 groups, 8 rats each: Group 2: Ob + HFD group, they continue their high animal fat diet, Group 3: Ob+HFD + corn oil group, they are obese rats received high fat diet containing corn oil and Group 4: Ob + HFD + Omega 3 group, they are obese rats, fed high animal fat diet supplemented with omega 3 (0.4 g/kg) daily. After five weeks, the final body weight was measured and BMI was calculated and blood samples were collected for measuring fasting plasma glucose level, insulin level and homeostasis model assessment of insulin resistance (HOMA-IR) test were evaluated. Plasma cholesterol, triglycerides and free fatty acids (FFAs) were measured. The rats were then killed and sciatic nerves were carefully dissected for measuring the nerve conduction velocity (NCV). Superoxide dismutase activity (SOD), malondialdehyde (MDA) and tumor necrosis factor alpha (TNFα) were estimated in the nerve tissue of the 4 groups. Results: The results of this study showed a significant increase of body weight (gm) and BMI (kg/m2) in high fat diet group (p< 0.05) after 12weeks of the start of the diet when compared to the control group (NC). There were significant elevations in the final weight (gm) and BMI (kg/m2), a significant elevation in insulin level (μIU/l) and HOMA-IR test, a significant increase in nerve malondialdehyde (MDA), and tumor necrosis factor alpha (TNFα) and a significant decrease in superoxide dismutase activity (SOD) and nerve conduction velocity (NCV) (m/s) after 5weeks of high fat diet in (Ob+HFD) group, when compared to NC group. Changing diet composition for 5weeks in Ob+ HFD+corn oil and Ob+HFD+omega 3 groups, did not induce any significant variation in body weight, BMI, or fasting blood glucose level as compared to Ob+HFD group. Insulin level (μIU/l) and HOMA-IR test were significantly decreased in Ob+ HFD+corn oil and Ob+HFD+omega 3 groups compared to Ob+HFD group. Plasma cholesterol levels (mg/dl), triglycerides (mg/dl), and free fatty acids (FFA) (mmol/l) were significantly decreased after 5weeks diet in Ob+ HFD+corn oil or Ob+HFD+ Omega 3 groups when compared to mean values of Ob+HFD group. Tissue malondialdehyde (MDA) and tumor necrosis factor alpha (TNFα) were significantly decreased but superoxide dismutase (SOD) activity was significantly increased in Ob+HFD+corn oil and Ob+HFD+omega3 groups compared to Ob+HFD. NCV(m/s) in Ob+HFD+ corn oil group was significantly increased compared to Ob+ HFD and their values in Ob+HFD+ corn oil group showed no significant variation as compared to NC group. While there was a significant increase in NCV in Ob+ HFD+Omega 3 group as compared to Ob+ HFD group, there was still a significant decrease compared to NC group. Conclusion: The results of this study may have important clinical and speculative implications. Corn oil or omega 3 supplementation may be effective in obesity induced neuropathy. The mechanism of their effects is multifactorial including improving insulin sensitivity, correction of dyslipdemia, reducing oxidative stress and an anti-inflammatory effect. This possibility should be carefully considered and examined in future trials of essential fatty acid supplementation.
This chapter reviews current research on polyunsaturated fatty acid metabolism in development, the supply of n-6 and n-3 fatty acids before and after birth, and the role of n-3 fatty acids in the developing brain and retina. The n-6 and n-3 polyunsaturated fatty acids are essential nutrients that are required for growth and normal cell function. These fatty acids are present in cells as the acyl moieties of phospholipids which make up the structural matrix of cell and subcellular membranes, and function directly, or as precursors to other molecules that modulate cell growth, metabolism, inter- and intracellular communication and gene expression. The n-3 fatty acid docosahexaenoic acid (22:6n-3) is accumulated in the retina and brain grey matter during development, recycled and replenished by uptake from plasma during the dynamic processes of signal transduction in the retina and neuronal membranes. The depletion results in reduced visual function, behavioural abnormalities, and alterations in the metabolism of neurotransmitters, and in membrane proteins, receptors and ion channel activities.
Zellweger's syndrome and related peroxisomal disorders are lethal congenital diseases whose pathogenesis is still poorly understood. The low levels of docosahexaenoic acid found in these patients seem to be related to the pathogenesis of the disease. This is confirmed by the fact that correcting their docosahexaenoic acid deficiency improves the patients significantly. All treatments currently reported involve the use of low-fat diets. This review presents a totally different therapeutic approach. The aim is to correct the docosahexaenoic acid deficiency in the first place, and give the child a normal diet in order to provide all the nutrients necessary for growth and development. The biochemical and clinical improvements produced by this approach suggest that, if given very early during development, docosahexaenoic acid therapy might prevent some of the devastating consequences of peroxisomal disorders.
Introduction–Lipids and Evolution The Evolution of Complex Life Forms The Language of Lipids DHA Evolution of Homo Sapiens DHA and Neural Pathways? A Comment on AA The Third Phase of Earth's Life History–AA and Reproduction in Mammals Darwin and the Conditions of Existence Implications Conclusion Acknowledgments Notes References
Key Points
The supply of dietary n-3 and n-6 fatty polyunsaturated fatty acids (PUFAs) affects the composition of plasma and red blood cell membrane lipids of term and preterm infants.
Human infants require docosahexaenoic acid (DHA) in their diet because they are unable to form this in sufficient quantity from the linoleic acid provided from vegetable oils.
Dietary n-3 fatty acid deficiency affects eye and brain function of preterm and term infants as measured by electrorelinogram, cortical visual-evoked potentials, and behavioral testing of visual acuity.
Technological procedures based on chemical and physical separation of the unsaturated fatty acids have permitted the elaboration of nearly pure eicosapentaenoic acid, DHA, and arachidonic acid (AA) for clinical use.
The development of single-cell oil sources and, more recently, genetically modified plants and animals provides novel forms of long-chain PUFA (LCPUFA) delivery.
Human milk is the best and only time proven source of fat and essential fatty acids and LCPUFAs in the infant diet.
Supplementation of formula with both DHA and AA has been demonstrated to support growth and development closer to that of human milk-fed infants without evidence of adverse effects.
The public health implications of these changes need to be fully evaluated to support this practice on a global scale.
Astrocytes are the most versatile cells of the neural tissue. Numerous astrocytic functions—such as protection from oxidative damage, catabolism of neuroactive D-amino acids acting as neuromodulators, synthesis and catabolism of some lipid molecules, and, possibly, gluconeogenesis—reside in peroxisomes. The expression of several peroxisomal enzymes, particularly those of the acyl-CoA -oxidation pathway, is regulated by a class of ligand-activated transcription factors, known as peroxisome proliferator-activated receptors (PPARs), acting on their target genes as heterodimers with the retinoid X receptors (RXRs). In this work, primary and secondary cultures of astrocytes from the cerebral cortices and cerebella of neonatal rats (2 and 7 days of postnatal age) were utilized to investigate the expression of peroxisomal enzymes, PPAR and RXR isotypes (, and ), by both biochemical and immunological methods. The results obtained demonstrate that astrocytes in vitro express peroxisomal enzymes, PPARs, and RXRs and that differences dependent on brain area, animal age, and culture time are reminiscent of the in vivo situation. Therefore, primary cultures of astrocytes and, particularly, high purified subcultures may constitute a useful model for further studies aimed to gain further insights into the roles of peroxisomes and PPARs related to lipid and glucose metabolism in these cells.
Given our current knowledge, there is a need for the early institution of immunomodulatory therapy, especially for patients with poor prognostic factors (motor and cerebellar symptoms, frequent disease exacerbations, and a high level of activity on magnetic resonance imaging [MRI]).
Patients who progress despite immunomodulatory therapy should be reevaluated in terms of diagnosis, development of neutralizing antibodies, or compliance. If a patient has a partial response to immunomodulatory therapy but his or her disease, as assessed by clinical and MRI criteria, remains very active, every effort should be made to modify disease progression by searching for an immunosuppressive therapy regimen before irreversible and considerable disability has accumulated.
For the majority of patients, multiple sclerosis (MS) is a chronic condition. Therefore, until a curative treatment has been developed, the available repertoire of immunosuppressive or immunomodulatory treatments should be assessed with respect to the possibility of long-term use. This is particularly important for new immunosuppressive drugs, such as cladribine or mitoxantrone, or for invasive procedures, such as total lymphoid irradiation or autologous bone marrow transplantation. For the latter treatments, experience with long-term administration is not available or the potential side effects (eg, cardiotoxicity with mitoxantrone) limit the cumulative dose. These considerations may limit long-term administration and thus the general usefulness of some drugs. Even with proven efficacy, we need to define the next step once treatment has to be discontinued. We should also address whether exacerbating disease by discontinuing an effective therapy is a potential hazard. What other therapeutic options remain once the current treatment is discontinued? Answers are not readily available at the moment, but the question should influence our decisions in the selection of traditional, well-studied or new, potentially promising therapies.
Life originated on this planet about 3 billion years ago. For the first 2.5 billion years of life there was ample opportunity for DNA modification. Yet there is no evidence of significant change in life forms during that time. It was not until about 600 million years ago, when the oxygen tension rose to a point where air-breathing life forms became thermodynamically possible, that a major change can be abruptly seen in the fossil record. The sudden appearance of the 32 phyla in the Cambrian fossil record was also associated with the appearance of intracellular detail not seen in previous life forms. That detail was provided by cell membranes made with lipids (membrane fats) as structural essentials. Lipids thus played a major, as yet unrecognised, role as determinants in evolution. The compartmentalisation of intracellular, specialist functions as in the nucleus, mitochondria, reticulo-endothelial system and plasma membrane led to cellular specialisation and then speciation. Thus, not only oxygen but also the marine lipids were drivers in the Cambrian explosion. Docosahexaenoic acid (DHA) (all-cis-docosa-4,7,10,13,16,19-hexaenoic acid, C22:6ω3 or C22:6, n-3, DHA) is a major feature of marine lipids. It requires six oxygen atoms to insert its six double bonds, so it would not have been abundant before oxidative metabolism became plentiful. DHA provided the membrane backbone for the emergence of new photoreceptors that converted photons into electricity, laying the foundation for the evolution of other signalling systems, the nervous system and the brain. Hence, the ω3 DHA from the marine food web must have played a critical role in human evolution. There is also clear evidence from molecular biology that DHA is a determinant of neuronal migration, neurogenesis and the expression of several genes involved in brain growth and function. That same process was essential to the ultimate cerebral expansion in human evolution. There is now incontrovertible support of this hypothesis from fossil evidence of human evolution taking advantage of the marine food web. Lipids are still modifying the present evolutionary phase of our species; their signature is evident in the changing panorama of non-communicable diseases. The most worrying change in disease pattern is the sharp rise in brain disorders, which, in the European Union, has overtaken the cost of all other burdens of ill health at €386 billion for the 25 member states at 2004 prices. In 2007, the UK cost was estimated at £77 billion and confirmed in 2010 at £105 billion - greater than heart disease and cancer combined. The rise in mental ill health is now being globalised. The solution to the rising vascular disorders in the last century and now brain disorders in this century lies in a radical reappraisal of the food system, which last century was focussed on protein and calories, with little attention paid to the requirements of the brain - the very organ that was the determinant of human evolution. With the marine fish catch having plateaued 20 years ago and its sustainability now under threat, a critical aspect of this revision is the development of marine agriculture from estuarine, coastal and oceanic resources. Such action is likely to play a key role in future health and intelligence.
Gray matter, white matter, and myelin were isolated from the frontal lobes of the brains of humans aged 10 months, 6 yr, 9 yr, and 55 yr. The major lipids, including ethanolamine glycerophosphatides (EGP), serine glycerophosphatides (SGP), choline glycerophosphatides (CGP), sphingomyelin, cerebroside, cerebroside sulfate, and ceramide were isolated by column chromatography and their fatty acid and fatty aldehyde compositions were determined by gas–liquid chromatography.
EGP and SGP from myelin had a fatty aldehyde composition which differed from that of EGP and SGP from gray matter; octadecenaldehydes were present in much higher proportions in these lipids from myelin than in those from gray matter. EGP and SGP also contained high proportions of 20- and 22-carbon polyunsaturated fatty acids, whereas CGP contained small proportions of these acids. Each glycerophosphatide from gray matter contained approximately 3- to 6-fold higher proportions of polyunsaturated fatty acids than did the same glycerophosphatide from myelin. Sphingomyelin, cerebroside, cerebroside sulfate, and ceramide also differed in their fatty acid compositions depending upon their tissue source; each sphingolipid from myelin in the younger subjects contained 5- to 9-fold higher proportions of long-chain fatty acids (C19-C26) than did the same sphingolipid from gray matter.
The lipids from myelin in the baby (10 months) were very similar to those from myelin in the adult, both with respect to their content of polyunsaturated fatty acids and to their content of long-chain fatty acids. These findings suggest that myelin in the baby is “chemically mature” in its lipid composition at an early age.
The hypothesis that the last step in the biosynthesis of 4,7,10,13,16,19-22:6 from linolenate is catalyzed by an acyl-CoA-dependent 4-desaturase has never been evaluated by direct experimentation. When rat liver microsomes were incubated with [1-14C]7,10,13,16,19-22:5, under conditions where linoleate was readily desaturated to 6,9,12-18:3, it was never possible to detect the product of the putative 4-desaturase. In the presence of malonyl-CoA, 7,10,13,16,19-22:5 was sequentially chain-elongated to 9,12,15,18,21-24:5, followed by its desaturation at position 6 to give 6,9,12,15,18,21-24:6. Microsomes desaturated 9,12,15,18,21-24:5 at rates similar to those observed for metabolizing linoleate to 6,9,12-18:3. Rat hepatocytes metabolize [1-14C]7,10,13,16,19-22:5 to 22:6(n-3), but in addition, it was possible to detect small amounts of esterified 24:5(n-3) and 24:6(n-3) in phospholipids, which is a finding consistent with their role as obligatory intermediates in 22:6(n-3) biosynthesis. When 3-14C-labeled 24:5(n-3) or 24:6(n-3) were incubated with hepatocytes, only a small amount of either substrate was esterified. [3-14C] 24:5(n-3) was metabolized both by beta-oxidation to 22:5(n-3) and by serving as a precursor for the biosynthesis of 24:6(n-3) and 22:6(n-3). The primary metabolic fate of [3-14C]24:6(n-3) was beta-oxidation to 22:6(n-3), followed by its acylation into membrane lipids. Our results thus document that 22:5(n-3) is the precursor for 22:6(n-3) but via a pathway that is independent of a 4-desaturase. This pathway involves the microsomal chain elongation of 22:5(n-3) to 24:5(n-3), followed by its desaturation to 24:6(n-3). This microsomal product is then metabolized, via beta-oxidation, to 22:6(n-3).
Docosahexaenoic acid [22:6 omega 3; 22:6-(4,7,10,13,16,19)] is the major polyunsaturated fatty acid in the photoreceptor membranes of the retina and in cerebral gray matter. It must be obtained either from the diet or by synthesis from other omega 3 fatty acids, chiefly alpha-linolenic acid (18:3 omega 3). We tested the effect of dietary omega 3 fatty acid deprivation during gestation and postnatal development upon the fatty acid composition of the retina and cerebral cortex and upon visual function. Rhesus monkeys (Macaca mulatta) were fed semipurified diets very low in 18:3 omega 3 throughout pregnancy, and their infants received a similar diet from birth. A control group of females and their infants received a semipurified diet supplying ample 18:3 omega 3. In near-term fetuses and newborn infants of the deficient group, the 22:6 omega 3 content of phosphatidylethanolamine was one-half of control values in the retina and one-fourth in cerebral cortex. By 22 months of age, the content of 22:6 omega 3 in these tissues approximately doubled in control monkeys, but it failed to increase in the deficient group. Low levels of 22:6 omega 3 in the deficient animals' tissues were accompanied by a compensatory increase in longer-chain omega 6 fatty acids, particularly 22:5 omega 6. Functionally, the deficient animals had subnormal visual acuity at 4-12 weeks of age and prolonged recovery time of the dark-adapted electroretinogram after a saturating flash. Abnormally low levels of 22:6 omega 3 may produce alterations in the biophysical properties of photoreceptor and neural membranes that may underlie these functional impairments. The results of this study suggest that dietary omega 3 fatty acids are retina and brain.
The pyrrolidide and picolinyl ester derivatives of the fatty acids in two natural lipid samples rich in unsaturated fatty acids, pig testis lipids and cod liver oil were satisfactorily resolved on capillary columns of fused silica coated with stationary phases of varying polarity. The picolinyl esters, in particular, when subjected to gas chromatography-mass spectrometry on a column containing a cross-linked methyl silicone, gave distinctive mass spectra, which could be interpreted in terms of both the numbers and positions of the double bonds.
To understand the possible role of phytanoyl-CoA ligase, present in the membrane, in the oxidation of phytanic acid in the matrix of peroxisomes (Pahan, K. and I. Singh. 1993. FEBS Lett. 333: 154-158) we examined the transport of phytanic acid/phytanoyl-CoA into peroxisomes and the topology of the active site of phytanoyl-CoA ligase in the peroxisomal membrane. The increase in lignoceroyl-CoA ligase as compared to no change in the activities of palmitoyl-CoA and phytanoyl-CoA ligases when peroxisomes were disrupted with detergent or sonication and inhibition of the activities of both palmitoyl-CoA and phytanoyl-CoA ligase by impermeable inhibitor of acyl-CoA ligases (mercury-dextran) and trypsin treatment in the intact peroxisomes. On the other hand, the lignoceroyl-CoA ligase activity was inhibited by mercury-dextran and trypsin only in the disrupted peroxisomes. Taken together, these studies support the conclusion that the enzymatic site of phytanoyl-CoA ligase is on the cytoplasmic surface of peroxisomal membrane. This implies that phytanoyl-CoA is synthesized on the cytoplasmic surface of peroxisomal membrane and is translocated through the membrane for its alpha-oxidation to pristanic acid in the matrix of peroxisomes. To delineate the transport for phytanic acid through the peroxisomal membrane, we examined cofactors and energy requirements for its transport into peroxisomes. The similar rates of transport of phytanoyl-CoA and phytanic acid under conditions favorable for fatty acid activation (presence of ATP, CoASH, and MgCl2) and the lack of transport of phytanic acid when ATP and/or CoASH were removed or replaced with their inactive analogues (ATP and/or CoASH) from assay medium clearly demonstrates that the transport of phytanic acid requires prior synthesis of phytanoyl-CoA by phytanoyl-CoA ligase. The prerequisite activation of phytanic acid to phytanoyl-CoA for its alpha-oxidation only in intact peroxisomes, and oxidation of free phytanic acid in digitonin-permealized peroxisomes or isolated matrix, suggests that phytanoyl-CoA ligase (in peroxisomal membrane) regulates the oxidation of phytanic acid in peroxisomes by providing phytanoyl-CoA for its transport into peroxisomes.
The purpose of this study was to determine whether the formation of docosahexaenoic acid in human cells occurs through a pathway that involves 24-carbon n-3 fatty acid intermediates and retroconversion. Normal human skin fibroblasts synthesized radiolabeled docosahexaenoic acid from [1-(14)C]18:3n-3, [3-(14)C]22:5n-3, [3-(14)C]24:5n-3, and [3-(14)C]24:6n-3. The amount of docosahexaenoate formed was reduced in fibroblasts defective in peroxisomal biogenesis, by 90-100% in Zellweger's syndrome and by 50-75% in infantile Refsum's disease. Fatty acid elongation and desaturation were intact in these mutant cells. No decrease in radiolabeled docosahexaenoic acid production occurred in mutant fibroblasts defective in peroxisomal alpha-oxidation or mitochondrial beta-oxidation, or in normal fibroblasts treated with methyl palmoxirate to inhibit mitochondrial beta-oxidation. Therefore, the retroconversion step in docosahexaenoic acid formation occurs through peroxisomal beta-oxidation in normal human cells. These results demonstrate that the pathway for docosahexaenoic acid synthesis in human cells involves 24-carbon intermediates. The limited ability to synthesize docosahexaenoic acid may underlie some of the pathology that occurs in genetic diseases involving peroxisomal beta-oxidation.
—A method is described for the fractionation of bulk isolated oligodendroglial cells from calf brain to produce both a plasma membrane and an attached myelin fraction. The cells are homogenized in a sucrose solution containing Mg²⁺ and K+ at a pH of 6·5. Crude membrane fractions are obtained from this homogenate by discontinuous sucrose density gradient centrifugation. After being subjected to osmotic shock, these fractions are purified by continuous sucrose density gradient centrifugation. The plasma membrane fraction, which bands at 1·0 m‐sucrose, was identified by its morphology and enzyme content. Electron microscopy showed it to be a homogeneous preparation of vesicles composed, for the most part, of smooth trilaminar membranes. Enzymatic analysis revealed the presence of high specific activities of Na+, K+‐ATPase, 5′‐nucleotidase and 2′,3′‐cyclic AMPase. Lipid analysis showed a higher galactolipid and lower phospholipid content than has been reported for neuronal and synaptic membranes. The attached myelin fraction, which bands at 0·7 m‐sucrose has the typical multilamellar appearance of myelin, but differs considerably from normal myelin in having high concentrations of plasma membrane marker enzymes, and a lipid composition intermediate between normal myelin and the plasma membrane fraction. The ganglioside content and protein patterns of these fractions have also been examined.
Bile acid conjugates are main excretory products of cholesterol catabolism. 3a,7a,12a-Trihydroxy-53-cholestanoic acid (THCA) and 3a,7a-dihydroxy-53-cholestanoic acid (DHCA) are immediate precursors to the primary bile acids, cholic acid and chenodeoxycholic acid, respectively. Subcellular fractionation studies have shown that the peroxisomal fractions from both rat and human liver catalyze most efficiently the conversion of THCA into cholic acid and DHCA into chenodeoxycholic acid. The mechanism for this C27-steroid side chain cleavage reaction is similar to that of the peroxisomal 3-oxidation of long chain fatty acids. Rat liver peroxisomes also have the ability to conjugate the end products of the reaction, the CoA esters of the bile acids, with glycine or taurine.
The importance of liver peroxisomes in vivo has been evaluated by studies of bile acid formation in patients with Zellweger syndrome, a fatal inherited disease with absent peroxisomes in liver and kidney. Bile and plasma of these patients contain high amounts of THCA and other bile acid intermediates with an uncleaved steroid side chain. By in vivo and in vitro studies we have shown that this accumulation is due to a defective peroxisomal oxidation of the side chain of THCA and DHCA. The accumulated THCA is converted to more polar secondary metabolites, presumably by microsomal enzymes. The pool size and the synthetic rate of cholic acid were reduced to about 1/10 of normal. We conclude that liver peroxisomes are essential for normal formation of bile acids in man.
Room temperature Size Exclusion Chromatography (SEC) for poly(ethylene terephthalate) (PET) was developed using a mobile phase mixture of 5% hexafluoroisopropanol (HFIP) in methylene chloride (MeCl2). Calibration was carried out with three different approaches, each time with and without considering the presence of cyclic oligomer in PET samples and standards. At typical concentrations of cyclic oligomer a calibration curve generated from a chromatogram truncated to eliminate the oligomer peak had its slope distorted such that it gave molecular weight average values inaccurate by up to 8%, whereas correcting for the oligomer explicitly resulted in average errors of about 1%. Although the effect of this small peak may be negligible for typical SEC applications involving repeated analysis of similar samples, it may alter the calibration curve significantly if not corrected.
The cerebro-hepato-renal syndrome is a rare familial malady with cerebral, renal, and skeletal abnormalities, severe hypotonia,
cirrhosis, iron and lipid storage, and death within 6 months. Correlated electron microscopic, histochemical, and biochemical
studies demonstrate defects in two oxidative organelles. Peroxisomes cannot be found in hepatocytes and renal proximal tubules.
In hepatocytes and cortical astrocytes, mitochondria are distorted in their appearance and glycogen stores are increased.
Oxygen consumnption of brain and liver mitochondrial preparations with succinate and with substrates reducing nicotinamide
adenine dinucleotide is markedly diminished, but the consumption is normal with ascorbate and tetramethylphenylenediamine,
which suggests a defect in electron transport prior to the cytochromes. Histochemical studies of mitochondrial oxidation point
to a defect between the succinate dehydrogenase flavoprotein and coenzyme Q, possibly in the region of nonheme iron protein.
Photoreceptor membrane phospholipids contain large quantities of ω3 and ω6 polyunsaturated fatty acids. Attempts to deplete these fatty acids from rod outer segments of rats by feeding a fat-free diet for 10–12 weeks were unsuccessful. Subsequent experiments showed that photoreceptor disc renewal is altered in the absence of dietary ω3 and/or ω6 fatty acids. We conclude that photoreceptor membrane renewal depends upon the availability of polyunsaturated fatty acids.Docosahexaenoic acid in photoreceptor membranes was significantly lowered by raising several generations of animals on modified fat-free diets. Electroretinographic experiments on these animals showed a decreased amplitude of the a-wave, suggesting that normal visual function is dependent upon dietary polyunsaturates.
—A method is described for the fractionation of bulk isolated oligodendroglial cells from calf brain to produce both a plasma membrane and an attached myelin fraction. The cells are homogenized in a sucrose solution containing Mg2+ and K+ at a pH of 6·5. Crude membrane fractions are obtained from this homogenate by discontinuous sucrose density gradient centrifugation. After being subjected to osmotic shock, these fractions are purified by continuous sucrose density gradient centrifugation. The plasma membrane fraction, which bands at 1·0 m-sucrose, was identified by its morphology and enzyme content. Electron microscopy showed it to be a homogeneous preparation of vesicles composed, for the most part, of smooth trilaminar membranes. Enzymatic analysis revealed the presence of high specific activities of Na+, K+-ATPase, 5′-nucleotidase and 2′,3′-cyclic AMPase. Lipid analysis showed a higher galactolipid and lower phospholipid content than has been reported for neuronal and synaptic membranes. The attached myelin fraction, which bands at 0·7 m-sucrose has the typical multilamellar appearance of myelin, but differs considerably from normal myelin in having high concentrations of plasma membrane marker enzymes, and a lipid composition intermediate between normal myelin and the plasma membrane fraction. The ganglioside content and protein patterns of these fractions have also been examined.
Abnormal mitochondrial structure and function have been documented in patients with Zellweger's syndrome (cerebrohepatorenal syndrome). In vitro studies have suggested that the formation of C24 bile acids (chenodeoxycholic acid and cholic acid) from C27 cholesterol requires mitochondrial oxidative clevage of the terminal three carbons of the side chain. Therefore, three patients with Zellweger's syndrome were examined for the presence of mitochondrial defects in bile acid synthesis. All three excreted excessive amounts of 3 alpha, 7 alpha-dihydroxy-5 beta-cholestan-26-oicacid, 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic acid, and 3 alpha, 7 alpha, 12 alpha, 24 xi-tetrahydroxy-5 beta-cholestan-26-oic acid (varanic acid), precursors of chenodeoxycholic acid and cholic acid that have undergone only partial side chain oxidation. These findings give added support to the role of mitochondrial oxidative side chain cleavage in the overall scheme of bile acid synthesis.
The polyunsaturated fatty acid (PUFA) composition of the brain was studied in 8 patients with Zellweger's syndrome (ZS), 3 with neonatal adrenoleukodystrophy (NALD), one with bifunctional enzyme deficiency (BED), one with X-linked adrenoleukodystrophy (X-ALD), and one with adrenomyeloneuropathy (AMN). The PUFA composition of the liver, kidney and retina was studied in 8, 6 and 1 patients with ZS, respectively. An infant with NALD and a child with rhizomelic chondrodysplasia punctata (RCDP) were also studied for the PUFA composition of the liver. The liver and kidney of the patient with X-ALD and the liver of the patient with AMN were included in the study. The fatty acid values in the peroxisomal patients were compared with control data obtained in the normal developing brain (38 cases), liver (9 cases), kidney (7 cases) and retina (16 cases). The brain of a patient with metachromatic leukodystrophy (MLD) and the liver of a child with Krabbe's disease (KD) were also studied for comparison. The most constant and severe abnormalify in all the peroxisomal patients was a drastic decrease in the total amount of docosahexaenoic acid (22:6ω3), especially in the brain. The other product of Δ4-desaturation, 22:5ω6, was generally decreased in the brain, liver and kidney of the ZS patients, but very much increased in the brain of two patients with NALD. The 22:6ω3/22:4ω6 ratio, which remains quite constant throughout normal brain development, was consistently decreased in the peroxisomal brain, in ZS as well as in NALD. This study confirms that, in classical Zellweger's syndrome, the two products of Δ4-desaturation are affected. In contrast, in neonatal adrenoleukodystrophy the deficiency is probably restricted to the ω3 product of Δ4-desaturation, docosahexaenoic acid, especially in the brain, while the other product, 22:5ω6, is either normal or increased, perhaps in an attempt to compensate for the 22:6ω3 deficiency in brain membranes.
In confirmation of previous findings, patients with Zellweger's syndrome had extremely low levels of docosahexaenoic acid (22:6 omega 3) in the brain, liver, and kidneys. The other product of delta 4 desaturation, 22:5 omega 6, was also very significantly decreased, as were the ratios 22:6 omega 3/22:5 omega 3 and 22:5 omega 6/22:4 omega 6, especially in the brain and liver of the Zellweger patients. The infant with pseudo-Zellweger's syndrome also had very low levels of 22:6 omega 3 and of the ratio 22:6 omega 3/22:5 omega 3 in all tissues, especially in the brain, where the index 22:5 omega 6/22:4 omega 6 was also very significantly reduced. The ratio 22:6 omega 3/22:4 omega 6 was markedly decreased in all tissues, in Zellweger's as well as in pseudo-Zellweger's syndrome. The findings reported here strongly reinforce the hypothesis of a new enzymatic defect in peroxisomal disorders involving the desaturation of long polyunsaturated fatty acids, especially of the omega 3 family.
Cerebro-hepato-renal (Zellweger) syndrome, adrenoleukodystrophy, and Refsum's disease patients can be divided into at least five distinct groups, according to the nature of their plasma changes and their fibroblast phytanic acid oxidase activities. The biochemical changes in the plasma vary from an increase in a single metabolite or group of structurally related metabolites, such as in X-linked adrenoleukodystrophy (ALD) and classical Refsum's disease, to an increase in a number of structurally distinct metabolites, as in neonatal ALD/Zellweger syndrome, and infantile Refsum's disease. All patients, with the exception of those with the X-linked form of adrenoleukodystrophy are deficient in phytanic acid oxidase activity. The great similarity observed in neonatal adrenoleukodystrophy/Zellweger syndrome and infantile Refsum's disease suggests that the basic biochemical lesion in each may be similar or at least closely related.
Infantile Refsum's disease was diagnosed in three male patients, presenting with facial dysmorphia, retinitis pigmentosa, neurosensory hearing loss, hepatomegaly, osteopenia and delayed growth and psychomotor development.
An elevated plasma phytanic acid concentration and a deficient phytanic acid oxidase activity in fibroblasts were found with an accumulation of very long chain fatty acids in plasma and fibroblasts. There were elevated pipecolic acid levels in plasma, urine and CSF, and abnormal bile acid metabolites in plasma.
Deficient activity of acylCoA: dihydroxyacetone phosphate acyl transferase was found in thrombocytes and fibroblasts of these patients as well as an impairedde novo plasmalogen biosynthesis in fibroblasts. These biochemical abnormalities, previously described in the Zellweger syndrome, suggest multiple peroxisomal dysfunction in our patients.
The fatty acid composition of red blood cells, fibroblasts, forebrain, liver and kidney were studied in a 3-month-old infant who died from Zellweger Syndrome, and the results were compared with those of age-matched controls. Besides a typical increase in the very long chain fatty acids 26:0 and 26:1 and a great reduction in the plasmalogen levels, confirming the diagnosis of Zellweger Syndrome, some striking changes in the polyunsaturated fatty acid patterns were discovered. The most important was a very drastic decrease in the values of 22:6 omega 3 and 22:5 omega 6, the two products of delta 4-desaturation. In the kidney, the level of 22:6 omega 3 fell below that of 26:0. Consequently, the ratio 26:0/22:6 omega 3 (and 26:1/22:6 omega 3) was most useful in emphasizing the fatty acid anomalies, especially in renal tissue, where the 26:0/22:6 omega 3 ratio increased to almost 200 times the normal values. Other significant, although less consistent fatty acid alterations were increases in 18:2 omega 6, 18:3 omega 6, 20:3 omega 6, 18:4 omega 3 and 20:4 omega 3, and a decrease in 20:4 omega 6 in some tissues. The existence is proposed of a new enzyme defect in peroxisomal disorders, involving the desaturase system of long chain polyunsaturated fatty acids.
The location inside rat liver parenchymal cells of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase; EC 1.1.1.34), the key regulatory enzyme in cholesterol biosynthesis, has been examined by immunoelectron microscopy and by subcellular fractionation. Although HMG-CoA reductase is generally thought to be exclusively a microsomal enzyme, we find that a substantial portion of cellular HMG-CoA reductase is localized in peroxisomes. Immunoelectron microscopic labeling of ultrathin frozen sections of normal rat liver, using two monoclonal antibodies to purified HMG-CoA reductase, showed that the enzyme is present in the peroxisomes at a higher concentration than at any other site inside the hepatocytes. Subcellular fractionation studies using Percoll and metrizamide gradients demonstrated a close correspondence of peaks of HMG-CoA reductase activity and of catalase activity, again revealing the presence of the reductase enzyme in peroxisomes. HMG-CoA reductase is therefore localized in peroxisomes in addition to being in the microsomal fraction.
The Zellweger cerebro-hepato-renal syndrome is a genetic disease characterized by the absence of peroxisomes and deficiency of glycerol-ether lipids in several tissues. We measured the activity of dihydroxyacetone phosphate (DHAP) acyltransferase, a peroxisomal enzyme with a major role in ether lipid synthesis, in fibroblasts and leukocytes from patients with Zellweger syndrome. Control skin and amniotic-fluid fibroblasts had normal activity of DHAP acyltransferase (0.28 to 0.3 nmol per minute per milligram of protein), whereas fibroblasts from three patients with Zellweger syndrome had deficient activity (0.013 +/- 0.006 nmol per minute per milligram of protein). The activity of the enzyme in leukocytes and levels of plasmalogens (the major class of cellular glycerol-ether lipids) in erythrocytes were also deficient in a patient, but normal levels of leukocyte enzyme and erythrocyte plasmalogens were found in her parents. Other enzymes of the acyl DHAP pathway exhibited alterations in fibroblasts from patients with Zellweger syndrome, and the activity of the glycerophosphate acyltransferase was also reduced. These results support prior studies emphasizing the role of peroxisomes and the acyl DHAP pathway in cellular ether lipid synthesis, establish Zellweger syndrome cells as valuable for elucidating peroxisomal functions, and provide prenatal and postnatal diagnostic assays as well as potential therapeutic strategies for Zellweger syndrome.
The deficient oxidation and accumulation of very-long-chain fatty acids in the Zellweger cerebro-hepato-renal syndrome (CHRS) and X chromosome-linked adrenoleukodystrophy (ALD), coupled with the observation that peroxisomes are lacking in CHRS, prompted us to investigate the subcellular localization of the catabolism of lignoceric acid (C24:0). Peroxisomal and mitochondrial-rich fractions were separated from rat liver crude mitochondria by sucrose density gradient centrifugation. Enzyme activity for the oxidation of [1-14C]palmitic acid to water-soluble acetate was 2- to 3-fold higher in the mitochondrial than in the peroxisomal-rich fraction whereas [1-14C]lignoceric acid was oxidized at a 2- to 3-fold higher rate in the peroxisomal than in the mitochondrial fraction. Moreover, unlike palmitic acid oxidation, lignoceric acid oxidation was not inhibited by potassium cyanide in either rat liver fractions or human skin cultured fibroblasts, showing that lignoceric acid is mainly and possibly exclusively oxidized in peroxisomes. We also conducted studies to clarify the striking phenotypic differences between CHRS and the childhood form of ALD. In contrast to CHRS, we found normal hepatocellular peroxisomes in the liver biopsy of a childhood ALD patient. In addition, in the presence of potassium cyanide, the oxidation of palmitic acid in cultured skin fibroblasts was inhibited by 62% in control and X chromosome-linked ALD patients compared with 88% in CHRS and neonatal ALD. This differential effect may be related to differences in peroxisomal morphology in those disorders.
The Zellweger syndrome is a lethal hereditary disease characterized by the absence of peroxisomes (microbodies) in liver and kidney, and variable abnormalities in mitochondria. We show here that tissues from five infants that had died of this syndrome contain less than 10% of the normal levels of phosphatidylethanolamine plasmalogen (pPE), a major phospholipid component of cellular membranes. Heart and muscle, but not other tissues, also contain a substantial fraction of phosphatidylcholine plasmalogen (pPC), and this fraction is also strongly reduced in the Zellweger patients. No other abnormalities in cellular phospholipids were detected. Key enzymes of the biosynthesis of plasmalogens have previously been shown to be exclusively located in the peroxisomes of rodent liver and the microperoxisomes of rodent brain. We infer that the corresponding enzymes are also located in peroxisomes in man and that the absence of peroxisomes in Zellweger patients leads to their inability to synthesize plasmalogens. Our results support the notion that the biosynthetic role of peroxisomes in mammals has thus far been underestimated. We suggest that the defect in plasmalogen synthesis and possibly as yet unknown peroxisomal reactions are responsible for the diverse abnormalities observed in Zellweger patients.
Rats were fed through four generations with a semisynthetic diet containing 1.0% sunflower oil (6.7 mg/g n-6 fatty acids, 0.04 mg/g n-3 fatty acids). Ten days before mating, half of the animals received a diet in which sunflower was replaced by soya oil (6.6 mg/g n-6 fatty acids, 0.8 mg/g n-3 fatty acids) and analyses were performed on their pups. Fatty acid analysis in isolated cellular and subcellular material from sunflower-fed animals showed that the total amount of unsaturated fatty acids was not reduced in any cellular or subcellular fraction (except in 60-day-old rat neurons). All material from animals fed with sunflower oil showed an important reduction in the docosahexaenoic acid content, compensated (except in 60-day-old rat neurons) by an increase in the n-6 fatty acids (mainly C22:5 n-6). When comparing 60-day-old animals fed with soya oil or sunflower oil, the n-3/n-6 fatty acid ratio was reduced 16-fold in oligodendrocytes, 12-fold in myelin, twofold in neurons, sixfold in synaptosomes, and threefold in astrocytes. No trienes were detected. Saturated and monounsaturated fatty acids were hardly affected. This study provides data on the fatty acid composition of isolated brain cells.
Department of Biological Chemistry and Mental Health Research Institute University of Michigan Ann Arbor, Michigan 48109
We describe the detailed clinical, pathologic, and biochemical features of brother and sister with the neonatal onset form of adrenoleukodystrophy, together with evidence of the biochemical defect. When compared with reports of previous cases, it becomes clear that this is a newly described clinical entity with remarkable uniformity of signs and very different from the usual childhood form. Some pathologic features are shared, including the morphologic abnormality of the adrenal in both neonatal and childhood forms, but deposition of abnormally metabolized lipids is more systemic and widespread in the neonatal form. The biochemistry of the disease is presented in both children and parents. Plasma values of long-chain fatty acid C26:0 are 0.328 +/- 0.18 micrograms/ml in a control population and 0.381 +/- 0.312 micrograms/ml in the father and mother. Values for C26:0 in the plasma of childhood adrenoleukodystrophy are 1.62 +/- 0.87 micrograms/ml and in our two cases, 2.79 micrograms/ml in the male, 1.83 micrograms/ml in the female. The basic biochemical defect appears to be a diminished capacity to oxidize these fatty acids leading to accumulation in cholesterol esters. Fatty acid oxidation to CO2 by cultured skin fibroblasts was 51% of control value for stearic acid, 5% for lignoceric acid in the male, and 39% of control value for stearic acid, 5% for lignoceric acid in the female. The genetics of this disease is different; whereas childhood adrenoleukodystrophy is X-linked, the neonatal onset form affects males and females equally and is most probably autosomally recessive in inheritance.
A considerable body of biological evidence has accumulated that suggests that docosahexaenoic acid (22:6n3) is an essential component in the nervous system. Moreover, it appears from these studies that long chain polyunsaturates of the n-6 family such as arachidonate (20:4n6) and docosapentaenoate (22:5n6) cannot substitute for 22:6n3. This evidence is briefly reviewed and two hypotheses centering upon either biochemical or biophysical aspects of polyunsaturate function are presented and discussed. It is concluded that a bioactive metabolite of 22:6n3 is not responsible for its function in brain and that the best hypothesis asserts that a membrane function of a 22:6n3-containing species of phospholipid, such as phosphatidylserine, is critical for optimal neural function. Moreover, data are presented indicating that the biophysical properties of various highly unsaturated species of phospholipid are distinguishable. It is further contended that these species are not randomly distributed in membranes and thus the differences in physical properties may be amplified. It is concluded that a conceptual framework is needed in which the distinct membrane roles of phospholipid species may be understood as a function of the positions and numbers of double bonds. Only then may the critical role of the highly unsaturated n-3 polyunsaturates in the brain and retina be understood.
The purpose of the study was to compare the polyunsaturated fatty acid (PUFA) status in patients with X-linked adrenoleukodystrophy or adrenomyeloneuropathy (X-ALD/AMN) with that in disorders of peroxisome biogenesis (PB). Total fatty acids and plasmalogens were quantified in plasma and red cells from 28 patients with X-ALD/AMN, 26 patients with generalized peroxisomal disorders, and 37 controls. Total fatty acid methyl esters and plasmalogen dimethyl acetals were obtained by direct transmethylation and separated by capillary column gas chromatography. The results confirm previous findings in that docosahexaenoic acid (DHA, 22:6n-3) was greatly decreased in both plasma and erythrocytes from patients with PB disorders. When nutritional conditions were adequate, patients with X-ALD/AMN had normal levels of DHA. A highly significant positive correlation was found between the levels of DHA and those of plasmalogens in peroxisomal patients. As in other tissues, the parent n-6 fatty acid, linoleic acid (LA, 18:2n-6) was significantly increased in red cells from PB patients, whereas arachidonic acid (20:4n-6) was virtually within normal limits. In clear contrast to red cells and other tissues, arachidonate was significantly lower in plasma from PB patients. The decrease in plasma arachidonate and the high tissue levels of LA suggest a defect of delta 6 desaturase and/or delta 5 desaturase in PB patients. The n-6 fatty acids were normal in X-ALD/AMN patients. The present data show that X-ALD/AMN patients do not have the profound PUFA alterations that PB patients have, at least in blood.
Docosahexaenoic acid (DHA, 22:6 omega 3) is a major constituent of brain membrane phospholipids and photoreceptor cells. Patients with generalized peroxisomal disorders have extremely low levels of DHA in the brain and other tissues. Since a DHA deficiency could explain some basic symptoms in peroxisomal-disorder patients, we tested the possible beneficial effects of DHA in two patients with neonatal adrenoleukodystrophy (NALD). Before the treatment, both patients had very low DHA levels in plasma and erythrocytes. We first gave DHA in the form of fish oil and, in both patients, the rapid increase in red-cell DHA levels indicated that this fatty acid was being absorbed and incorporated into membrane phospholipids very fast. However, a low ratio 22:6 omega 3/22:5 omega 3 was still present in erythrocyte membranes, and the content of 20:5 omega 3 (eicosapentaenoic acid) was too high with the fish oil diet. We then began treatment with pure DHA ethyl ester and, after a few weeks, erythrocyte omega 3 polyunsaturated fatty acids were normal. There was an increase in the 18:0 molecular species of plasmalogens in both patients, most significantly in the child with affected plasmalogen biosynthesis in cultured fibroblasts. In the less severely affected NALD patient, treatment with DHA produced a very significant decrease in the ratios 24:1/22:0 and 26:1/22:0, and this child improved neurologically. The present data suggest that DHA deficiency may be the cause for some of the most characteristic abnormalities in peroxisomal-disorder patients and open new therapeutic possibilities for these patients.
A patient with classic Zellweger syndrome was treated with docosahexaenoic acid ethyl ester (DHA-EE) for three months. Five other patients with Zellweger variants (four of them less than one-year-old and a five-year-old) were treated with DHA-EE until normalization of the DHA levels in erythrocytes. When arachidonic acid (AA) concentration decreased, AA was added to the diet. Thereafter, a combined treatment with DHA plus AA followed, in a variable proportion that allowed the high levels of DHA in erythrocytes to be maintained. In the patient with Zellweger syndrome, DHA therapy produced an increase in plasmalogen and a decrease in 26:0 and 26:1. No clear clinical improvement could be detected in this patient during the short period of treatment with DHA-EE. The most consistent clinical effect produced by DHA therapy in the other patients with disorders of peroxisomal biogenesis was visual improvement, even in those patients that were virtually blind before the treatment. In general, the developmental curve began to accelerate. The infants became more alert, acquired better visual and social contact and muscular tone improved, with the beginning of good head control. The liver tests tended to normalize and some patients showed a reduction of hepatomegaly. All these favorable changes occurred when the patients were taking the DHA-EE alone. In some of the patients, muscular tone seemed to improve further after introducing AA supplements. From the biochemical point of view, the plasmalogen levels increased in most cases in erythrocytes, and the two ratios 26:0/22:0 and 26:1/22:0 decreased in plasma. In some patients there was a tendency for 26:1 to increase in plasma and for 18:0 plasmalogen to decrease in erythrocytes when AA was introduced in the diet. The significance of these findings remains to be elucidated, but they stress the importance of strict monitoring and control of the polyunsaturated fatty acids status during DHA therapy.
Patients with Zellweger syndrome and related peroxisomal disorders have profound changes in the polyunsaturated fatty acid (PUFA) patterns in brain and other tissues, with a constant decrease in docosahexaenoic acid (DHA, 22: 6ω3) concentration. Arachidonic acid (AA, 20:4ω6) concentration is normal or increased and linoleic acid (LA, 18: 2ω6) is increased in the brain of Zellweger patients. In the retina of these patients, the levels of DHA are extremely low. Since these alterations are reflected elsewhere, they can be detected in vivo in patients with generalized peroxisomal disorders by measuring the PUFA content of plasma and erythrocytes, which show very low concentrations of DHA. The concentration of AA is low in plasma in generalized peroxisomal patients, although it is within normal limits in erythrocytes. Patients with X-linked adrenoleukodystrophy (X-ALD) or adreno-myeloneuropathy (AMN) have a normal DHA and AA content in both plasma and erythrocytes, unless they receive extremely low-PUFA diets.
Alterations in the metabolism of arachidonic (20:4n-6), docosapentaenoic (22:5n-6), and docosahexaenoic (22:6n-3) acids and other polyunsaturated fatty acids in Zellweger syndrome and other peroxisomal disorders are reviewed. Previous proposals that peroxisomes are necessary for the synthesis of 22:6n-3 and 22:5n-6 are critically examined. The data suggest that 22:6n-3 is biosynthesized in mitochondria via a channelled carnitine-dependent pathway involving an n-3-specific delta-4 desaturase, while 20:4n-6, 20:5n-3 and 22:5n-6 are synthesized by both mitochondrial and microsomal systems; these pathways are postulated to be interregulated as compensatory-redundant systems. Present evidence suggests that 22:6n-3-containing phospholipids may be required for the biochemical events involved in successful neuronal migration and developmental morphogenesis, and as structural cofactors for the functional assembly and integration of a variety of membrane enzymes, receptors, and other proteins in peroxisomes and other subcellular organelles. A defect in the mitochondrial desaturation pathway is proposed to be a primary etiologic factor in the clinicopathology of Zellweger syndrome and other related disorders. Several implications of this proposal are examined relating to effects of pharmacological agents which appear to inhibit steps in this pathway, such as some hypolipidemics (fibrates), neuroleptics (phenothiazines and phenytoin) and prenatal alcohol exposure.
) acids in Zellweger syndrome and other peroxisomal disorders
- J P Infante
- V A Huszagh
The metabolic and molecular bases of inherited disease
- P B Lazarow
- H W Moser