Julie A Chowen

Hospital Infantil Universitario Niño Jesús · Department of Endocrinology

Diets rich in saturated fats are more detrimental to health than those containing mono‐ or unsaturated fats. Fatty acids are an important source of energy, but they also relay information regarding nutritional status to hypothalamic metabolic circuits and when in excess can be detrimental to these circuits. Astrocytes are the main site of central f...

Background Prepubertal children with obesity frequently have enhanced growth, accelerated skeletal maturation and changes in the GH-IGF axis. However, the involvement of pappalysins (PAPP-A, PAPP-A2) and stanniocalcins (STC1, STC2) as regulators of IGF bioavailability has not been studied in obesity. Objective We aimed to determine the effects of...

Background Children with pregnancy-associated plasma protein-A2 ( PAPP-A2 ) mutations resulting in low levels of bioactive insulin-like growth factor-1 (IGF1) and progressive postnatal growth retardation have improved growth velocity and height following recombinant human (rh)IGF1 treatment. The present study aimed to evaluate whether Pappa2 defici...

Astrocytes are no longer considered as passive support cells. In the hypothalamus, these glial cells actively participate in the control of appetite, energy expenditure and the processes leading to obesity and its secondary complications. Here we briefly review studies supporting this conclusion and the advances made in understanding the underlying...

Context: Prader-Willi syndrome (PWS) is associated with impaired growth hormone (GH) secretion and decreased insulin-like growth factor (IGF)-I levels. Pappalysins (PAPP-A, PAPP-A2) and stanniocalcins (STC-1, STC-2) regulate IGF binding-protein (IGFBP) cleavage and IGF bioavailability, but their implication in PWS is unknown. Objective: We deter...

Context Anorexia nervosa (AN) can cause severe undernutrition associated with alterations in the insulin-like growth factor (IGF) axis. Pappalysins (PAPP-A, PAPP-A2) and stanniocalcins (STC-1, STC-2) modulate IGF binding-protein (IGFBP) cleavage and IGF bioavailability, but their implications in AN are unknown. Objective We determined serum levels...

Dietary restriction is a frequent strategy for weight loss, but adherence is difficult and returning to poor dietary habits can result in more weight gain than that previously lost. How weight loss due to unrestricted intake of a healthy diet affects the response to resumption of poor dietary habits is less studied. Moreover, whether this response...

Aim: In addition to functioning as an energy sensor switch, AMPK plays a key role in the maintenance of cardiovascular homeostasis. However, obesity disrupts AMPK signaling, contributing to endothelial dysfunction and cardiovascular disease. This study aimed to elucidate if a short-term dietary intervention consisting in replacing the high-fat die...

Background Patients with pregnancy-associated plasma protein-A2 (PAPP-A2) mutations have progressive postnatal growth retardation and high circulating levels of IGF1 bound in ternary complexes. The present study aims to assess whether Pappa2 deficiency is associated with sex-specific differences in the main components of IGF1 ternary complexes and...

Objective: The aim of the current study was to evaluate the influence of HFD on the functionality of LepR by quantifying phosphorylated levels of 705Tyr-STAT3 in hippocampus astrocytes from mice that consumed an HFD either during the juvenile or the adult period. Methods: Five- and eight-week-old male mice, fed during 8 weeks with either control...

Leptin receptors (LepR) are expressed in brain areas controlling food intake homeostasis, such as the hypothalamus, the hippocampus and the prefrontal cortex. In a previous study we reported that long-term intake of saturated and monounsaturated fat alters hypothalamic LepR signalling. The current study aims at investigating the effect of foods hig...

Astrocytes influence neighboring neurons through the release of a variety of signals, including exosomes, micro-vesicles that contain a vast heterogeneity of molecules such as cytokines, growth factors, RNAs and micro-RNAs (mi-RNAs) that modify target cells. We hypothesized that hypothalamic astrocytes communicate the metabolic status via exosomes...

The propensity to develop neurodegenerative diseases is influenced by diverse factors including genetic background, sex, lifestyle, including dietary habits and being overweight, and age. Indeed, with aging, there is an increased incidence of obesity and neurodegenerative processes, both of which are associated with inflammatory responses, in a sex...

Leptin is involved in the modulation of insulin signaling in peripheral tissues, being closely associated with changes in lipid metabolism. This adipokine modifies inflammatory pathways that can interact with insulin targets in peripheral organs; however, the mechanisms remain unclear. Inflammatory and insulin signaling targets, cytokines, adiponec...

Exosomes are extracellular micro-vesicles with a complex content that include a vast heterogeneity of molecules such as growth factors, cytokines and RNAs, including micro-RNAs (mi-RNAs) that affect target cells. Neurons are influenced by neighboring astrocytes through the release of exosomes amongst other signals. We postulated that the metabolic...

Background: Development of obesity and its comorbidities is not only the result of excess energy intake, but also of dietary composition. Understanding how hypothalamic metabolic circuits interpret nutritional signals is fundamental to advance towards effective dietary interventions. Objective: We aimed to determine the metabolic response to die...

The growth hormone (GH)/insulin-like growth factor (IGF) axis plays fundamental roles during development, maturation, and aging. Members of this axis, composed of various ligands, receptors, and binding proteins, are regulated in a tissue- and time-specific manner that requires precise control that is not completely understood. Some of the most rec...

Dietary intervention is a common tactic employed to curtail the current obesity epidemic. Changes in nutritional status alter metabolic hormones such as insulin or leptin, as well as the insulin-like growth factor (IGF) system, but little is known about restoration of these parameters after weight loss in obese subjects and if this differs between...

Leptin modulates insulin signaling and this involves the Akt pathway, which is influenced by changes in the inflammatory environment and with leptin regulating cytokine synthesis. We evaluated the association between activation of the insulin-signaling pathway and alterations in pro- and anti-inflammatory cytokine levels in inguinal fat and liver o...

Leptin has been suggested to play a role in amyotrophic lateral sclerosis (ALS), a fatal progressive neurodegenerative disease. This adipokine has previously been shown to be associated with a lower risk of ALS and to confer a survival advantage in ALS patients. However, the role of leptin in the progression of ALS is unknown. Indeed, our understan...

Consumption of high-fat diets (HFD) has been associated with neuronal plasticity deficits and cognitive disorders linked to the alteration of glutamatergic disorders in the hippocampus. As young individuals are especially vulnerable to the effects of nutrients and xenobiotics on cognition, we studied the effect of chronic consumption of saturated (...

Long-term high-fat diet (HFD) consumption commonly leads to obesity, a major health concern of western societies and a risk factor for Alzheimer's disease (AD). Both conditions present glial activation and inflammation and show sex differences in their incidence, clinical manifestation, and disease course. HFD intake has an important impact on gut...

Leptin has been suggested to play a role in amyotrophic lateral sclerosis (ALS), a fatal progressive and neurodegenerative disease. This adipokine has previously been shown to be associated with a lower risk of ALS disease and to confer a survival advantage in ALS patients. However, the role of leptin in the progression of ALS is unknown. Indeed, o...

Maternal malnutrition in critical periods of development increases the risk of developing short- and long-term diseases in the offspring. The alterations induced by this nutritional programming in the hypothalamus of the offspring are of special relevance due to its role in energy homeostasis, especially in the endocannabinoid system (ECS), which i...

It is now clear that hypothalamic astrocytes participate in maintaining metabolic homeostasis. Both nutrients and metabolic hormones can directly impact on these glial cells to modify their release of gliotransmitters, metabolic factors, growth factors, etc, as well as their physical interaction with neighboring neurons. Another mechanism by which...

Maternal nutritional imbalances, in addition to maternal overweight and obesity, can result in long-term effects on the metabolic health of the offspring, increasing the risk of common non-communicable disorders such as obesity, diabetes and cardiovascular disease. This increased disease risk may also be transmitted across generations. Unfortunatel...

Deficiency of pregnancy-associated plasma protein-A2 (PAPP-A2), an IGF-1 availability regulator, causes postnatal growth failure and dysregulation of bone size and density. The present study aimed to determine the effects of recombinant murine IGF-1 (rmIGF-1) on bone composition and remodeling in constitutive Pappa2 knock-out (ko/ko) mice. To addre...

Vegetable oils such as palm oil (enriched in saturated fatty acids, SFA) and high-oleic-acid sunflower oil (HOSO, containing mainly monounsaturated fatty acids, MUFA) have emerged as the most common replacements for trans-fats in the food industry. The aim of this study is to analyze the impact of SFA and MUFA-enriched high-fat (HF) diets on endoth...

The growth hormone (GH)/insulin-like growth factor I (IGF-I) axis is involved in metabolic control. Malnutrition reduces IGF-I and modifies the thermogenic capacity of brown adipose tissue (BAT). Leptin has effects on the GH/IGF-I axis and the function of BAT, but its interaction with IGF-I and the mechanisms involved in the regulation of thermogen...

Central actions of leptin and insulin on hepatic lipid metabolism can be opposing and the mechanism underlying this phenomenon remains unclear. Both hormones can modulate the central somatostatinergic system that has an inhibitory effect on growth hormone (GH) expression, which plays an important role in hepatic metabolism. Using a model of chronic...

Diseases and aging-associated alterations of the nervous system often show sex-specific characteristics. Glial cells play a major role in the endogenous homeostatic response of neural tissue, and sex differences in the glial transcriptome and function have been described. Therefore, the possible role of these cells in the generation of sex differen...

Alzheimer’s disease (AD) is the most common form of dementia and has a higher incidence in women. The main component of the senile plaques characteristic of AD is amyloid-beta (Aβ), with surrounding astrocytes contributing to the degenerative process. We hypothesized that the sex difference in the incidence of AD could be partially due to different...

This volume discusses current research on glial-neuronal interactions in several neuroendocrine systems. Glial-neuronal bidirectional transmission represents one of the fastest-growing areas of investigation in neuroscience today. Unraveling the interactions and signaling synergy between glial cells and neurons is critical to advancing our understa...

The insulin-like growth factor (IGF) system is responsible for growth, but also affects metabolism and brain function throughout life. New IGF family members (i.e., pappalysins and stanniocalcins) control the availability/activity of IGFs and are implicated in growth. However, how diet and obesity modify this system has been poorly studied. We expl...

Background: Body fat content and distribution in childhood is influenced by sex and puberty, but interethnic differences in the percentage and distribution of body fat also exist. The abdominal visceral/subcutaneous fat ratio has been the main feature of body fat distribution found to associate with the serum adipokine profile and metabolic derange...

Aim: We aimed to investigate whether maternal malnutrition during gestation/lactation induces long-lasting changes on inflammation, lipid metabolism and endocannabinoid signaling in the adult offspring hypothalamus and the role of hypothalamic astrocytes in these changes. Methods: We analyzed the effects of a free-choice hypercaloric palatable diet...

Insulin-like growth factor (IGF) 1 exerts a wide range of functions in mammalians participating not only in the control of growth and metabolism, but also in other actions such as neuroprotection. Nutritional status modifies the IGF system, although little is known regarding how diet affects the newest members of this system including pregnancy-ass...

Background In obesity adipose tissue undergoes structural re‐modelling leading to a chronic low‐grade inflammatory state linked to insulin resistance (IR). Objective We aimed to develop a clinically relevant biomarker model for stratifying IR in adolescents with obesity. Methods Cytokines [tumour cell derived factor 1α, monocyte chemoattract prot...

Background Recent studies have demonstrated that alcohol consumption can modulate the immune system by directly activating natural immunity and triggering inflammatory processes in the central nervous system and in peripheral organs, such as the liver and pancreas. Patients with alcohol use disorders have an elevated frequency of comorbid mental di...

Maternal nutrition can affect the susceptibility of the offspring to metabolic disease later in life, suggesting that this period is a window of opportunity for intervention to reduce the risk of metabolic disease. Resveratrol, a natural polyphenol, has a wide range of beneficial properties including anti-obesogenic, anti-atherosclerotic, and anti-...

Communication between astrocytes and neurons is fundamental for correct functioning of the brain, in both physiological and pathophysiological situations. It is clear that astrocytes play an active role in metabolic control, but much is yet to be learned regarding how these glial cells and the neurons involved in energy intake/expenditure communica...

Astrocytes, one of the most abundant cell types in the hypothalamus, perform a myriad of functions throughout all stages of development. Radial glia, astroglia-like progenitor cells, are fundamental for neurogenesis, neuronal migration, axon extension, and synaptic formation throughout the brain. These progenitor cells also give rise to mature astr...

Background: Obesity is a very heterogeneous disorder at both the clinical and molecular levels and with high heritability. Several monogenic forms and genes with strong effects have been identified for non-syndromic severe obesity. Novel therapeutic interventions are in development for some genetic forms, emphasizing the importance of determining...

Estradiol not only participates in the regulation of energy metabolism in adulthood, but also during the first stages of life as it modulates the alterations induced by under- and over-nutrition. The objectives of the present study were to determine: 1) If estradiol is involved in the normal programming of energy metabolism in rats; 2) If there is...

The aim of this study was to indentify the involvement of leptin receptors (LepR) in astrocytes in hippocampal synaptic transmission and plasticity and metabolism. To this end we used a genetic mouse model (GFAP-LepR−/−) of specific LepR ablation in GFAP positive cells and recorded excitatory postsynaptic potentials (fEPSPs) within the CA1 area. Gl...

Microglia, the primary regulators of inflammatory responses in the brain, suffer deterioration during aging culminating in their inability to generate adequate adaptive responses to maintain physiological homeostasis in brain tissue. Microglia affect the function of other glial cells and neurons, including those involved in the hypothalamic control...

Background: The capacity to correctly assess insulin resistance and its role in further obesity-associated metabolic derangement in children is under debate, and its determinants remain largely unknown. Objective: We investigated the association of the insulin secretion profile with other metabolic derangements and anthropometric features in chi...

Obesity is one of the most important health problems facing developed countries as being overweight is associated with a higher incidence of type 2 diabetes, cardiovascular disease, cancer, as well as other comorbidities. Although increased weight gain results from a combination of poor dietary habits and decreased energy expenditure, not all indiv...

Background: Maternal nutrition is a pivotal factor in determining long-term energy homeostasis in the offspring. However, whether resveratrol (R), with antioxidant and anti-obesity actions, can improve the long-term impact of poor maternal nutrition on the physiological function of white adipose tissue in the offspring is unknown. We previously rep...

The insulin like-growth factor (IGF) system is involved in numerous physiological functions including growth, development, metabolism, longevity, and neuroprotection. Obesity alters the peripheral IGF1 system, but its effects on the central IGF1 system or whether dietary factors have direct effects on this system remains unclear. Moreover, little i...

The role of glial cells, including astrocytes, in metabolic control has received increasing attention in recent years. Although the original interest in these macroglial cells was due to the observation that astrogliosis occurs in the hypothalamus of diet‐induced obese subjects, studies have also focused on how they participate in the physiological...

Astrocytes, microglia, and tanycytes play active roles in the regulation of hypothalamic feeding circuits. These non-neuronal cells are crucial in determining the functional interactions of specific neuronal subpopulations involved in the control of metabolism. Recent advances in biology, optics, genetics, and pharmacology have resulted in the emer...

Aim: We aimed to investigate whether a dysregulated maternal diet during gestation and lactation induces long‐lasting changes in the hypothalamic control of feeding behavior in the offspring and whether this effect is sex specific. Methods: The study included an analysis of appetite‐regulating metabolic hormones and hypothalamic signaling in male...

Background Insulin resistance (IR) in children with obesity constitutes a risk factor that should be precisely diagnosed to prevent further comorbidities. Objective Chemokines were evaluated to identify novel predictors of IR with clinical application. Methods We analysed the levels of cytokines (tumour necrosis factor [TNF] α and interleukins [I...

The hypothalamus is the main integrating center for metabolic control. Our understanding of how hypothalamic circuits function to control appetite and energy expenditure has increased dramatically in recent years, due to the rapid rise in the incidence of obesity and the search for effective treatments. Increasing evidence indicates that these trea...

Objective Mutations in the pregnancy-associated plasma protein A2 (PAPP-A2) gene have recently been shown to cause postnatal growth failure in two prepubertal patients from a non-consanguineous Spanish family due to the resulting decrease in IGF1 bioavailability. Although a specific pharmacological treatment of this entity is yet to be established...

After 6 years of Growth Hormone (GH) therapy, three patients with a defect in minor spliceosome mRNA processing leading to an incompletely understood GH deficit present with excellent auxological response and improvement in the bone mineral density and trabecular bone structure.

Proper nutrition is important for growth and development. Maturation of the reproductive axis and the timing of pubertal onset can be delayed when insufficient nutrition is available, or possibly advanced with nutritional abundance. The childhood obesity epidemic has been linked to a secular trend in advanced puberty in some populations. The increa...

Aim: Our objective was to determine changes in bone mineral density (BMD), trabecular bone score (TBS), and body composition after 2 years of therapy with recombinant human insulin-like growth factor-1 (rhIGF-1) in 2 prepubertal children with a complete lack of circulating PAPP-A2 due to a homozygous mutation in PAPP-A2 (p.D643fs25*) resulting in...

Somatostatin (SRIF), a neuropeptide highly distributed in the hippocampus and involved in learning and memory, is markedly reduced in the brain of Alzheimer's disease patients. The effects of insulin-like growth factor-I (IGF-I) against β amyloid (Aβ)-induced neuronal death and associated cognitive disorders have been extensively reported in experi...

The incorporation of plasma triglyceride (TG) fatty acids to white adipose tissue (WAT) depends on lipoprotein lipase (LPL), which is regulated by angiopoietin-like protein-4 (ANGPTL-4), an unfolding molecular chaperone that converts active LPL dimers into inactive monomers. The production of ANGPTL-4 is promoted by fasting and repressed by feeding...

Poor maternal nutrition can have detrimental long-term consequences on energy homeostasis in the offspring. Resveratrol exerts anti-oxidant and anti-obesity actions, but its impact during development remains largely unknown. We hypothesized that resveratrol intake during pregnancy and lactation could improve the effects of poor maternal nutrition o...

Sex differences in the incidence, clinical manifestation, disease course, and prognosis of neurological diseases, such as autism spectrum disorders or Alzheimer's disease, have been reported. Obesity has been postulated as a risk factor for cognitive decline and Alzheimer's disease and, during pregnancy, increases the risk of autism spectrum disord...

Astrocytes participate in both physiological and pathophysiological responses to metabolic and nutrient signals. While most studies have focused on the astrocytic response to weight gain due to high fat/high carbohydrate intake, surplus intake of a balanced diet also induces excess weight gain. We have accessed the effects of neonatal overnutrition...

An excess of saturated fatty acids can be toxic for tissues, including the brain, and this has been associated with the progression of neurodegenerative diseases. Since palmitic acid (PA) is a free fatty acid that is abundant in the diet and circulation and can be harmful, we have investigated the effects of this fatty acid on lipotoxicity in hippo...

Background Cocaine use disorder (CUD) is a complex health condition, especially when it is accompanied by comorbid psychiatric disorders (dual diagnosis). Dual diagnosis is associated with difficulties in the stratification and treatment of patients. One of the major challenges in clinical practice of addiction psychiatry is the lack of objective b...

Sociodemographic psychiatric and molecular levels

Insulin potentiates leptin effects on muscle accrual and glucose homeostasis. However, the relationship between leptin's central effects on peripheral insulin sensitivity and the associated structural changes remain unclear. We hypothesized that central leptin infusion modifies muscle size through activation of insulin signaling. Muscle insulin sig...

The discovery of a mutation in a specific gene can be very important for determining the pathophysiology underlying the disease of a patient and may also help to decide the best treatment protocol on an individual basis. However, sometimes the discovery of mutations in new proteins advances our comprehension in a more widespread manner. The growth...

Purpose Our aim was to characterize the effect of an unfamiliar high-fat diet (HFD) on circadian feeding behaviour, plasma parameters, body weight (BW), and gene expression in the prefrontal cortex (PFC) of adolescent male mice. To this end, mice were allowed to consume a HFD during 48 h, but one group was allowed a free choice of HFD or normal cho...

Background: Overnutrition due to a high-fat diet (HFD) can increase the vulnerability of the metabolic system to maladjustments. Estradiol has an inhibitory role on food intake and this hormone has demonstrated to be a crucial organizer during brain development. Objective: Our aim was to determine whether increased levels of estradiol in the early...

The crosstalk between the immune system and the en- docrine axis that controls appetite and metabolism is currently in the spotlight, largely due to the demon- stration that inflammatory processes are activated in response to poor dietary habits and obesity (1–3). However, it appears that we are only beginning to un- derstand the depth of the impor...

Many studies have shown the importance of an adequate nutritional environment during development to optimally establish the neurohormonal circuits that regulate feeding behaviour. Under- or over-nutrition during early stages of life can lead to alterations in the physiology and brain networks that control food intake, resulting in a greater vulnera...

Background/objectives: Insulin resistance (IR) is the cornerstone of the obesity-associated metabolic derangements observed in obese children. Targeted metabolomics was employed to explore the pathophysiological relevance of hyperinsulinemia in childhood obesity in order to identify biomarkers of IR with potential clinical application. Subjects/m...

The importance of the neonatal leptin surge in rodents in neurodevelopmental processes has aroused curiosity in its implication in other physiological systems. Given the role of leptin in neuro-immune interactions, we hypothesized that the neonatal leptin surge could have an effect on the oxidative and inflammatory stress situations of both systems...

Males and females have distinct propensities to develop obesity and its related comorbidities, partially due to gonadal steroids. There are sex differences in hypothalamic neuronal circuits, as well as in astrocytes, that participate in metabolic control and the development of obesity-associated complications. Astrocytes are involved in nutrient tr...

Obesity is frequently associated with chronic low-grade systemic inflammation, which is believed to underlie the onset of secondary complications of this disease (1,2). In 2005, studies from the laboratory of Dr. Licio Velloso in Brazil indicated that inflammatory processes in the hypothalamus are also activated in response to diet-induced obesity...

Maternal deprivation (MD) during neonatal life has diverse long-term effects, including modification of metabolism. We have previously reported that MD modifies the metabolic response to high-fat diet (HFD) intake, with this response being different between males and females, while previous studies indicate that in mice with HFD-induced obesity, en...

Although astrocytes are the most abundant cells in the mammalian brain, much remains to be learned about their molecular and functional features. Astrocytes express receptors for numerous hormones and metabolic factors, including the appetite-promoting hormone ghrelin. The metabolic effects of ghrelin are largely opposite to those of leptin, as it...

Although the brain is composed of numerous cell types, neurons have received the vast majority of attention in the attempt to understand how this organ functions. Neurons are indeed fundamental but, in order for them to function correctly, they rely on the surrounding “non-neuronal” cells. These different cell types, which include glia, epithelial...

Recent studies have linked changes in peripheral chemokine concentrations to the presence of both addictive behaviors and psychiatric disorders. The present study further explore this link by analyzing the potential association of psychiatry comorbidity with alterations in the concentrations of circulating plasma chemokine in patients of both sexes...

Background: Maternal deprivation (MD) during neonatal life can have long-term effects on metabolism and behavior, with males and females responding differently. We previously reported that MD during 24 h at postnatal day (PND) 9 blocks the physiological neonatal leptin surge in both sexes. It is known that modifications in neonatal leptin levels c...