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Hematoxylin and eosin staining of the rat brain cortex, hippocampus and areas surrounding the lateral ventricles in the normal control and hypoxic-ischemic (HI) groups at x100 and x400 magnification.
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This study aimed to investigate the role of iron in the occurrence and development of hypoxic-schemic brain injury (HIBI) in immature rat models using 3-day-old Sprague Dawley rats. Normal control (NC), hypoxic-ischemic (HI), anemia, HI + ischemia, early iron treatment and late iron treatment groups were established. Rat brain tissue sections were...
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Context 1
... staining of the rat brain tissue sections. In the NC group, the brain tissues looked healthy, with neatly ordered, normally shaped cells with a central nucleus and clearly visible nucleoli (Fig. 1). However, in the HI group, a large number of cells in the cortical, hippocampal and periventricular areas exhibited necrosis, vacuolar degeneration, nuclear condensa- tion and fragmentation. In some cases, dissolution of the nucleus was ...
Citations
... As a type of cell death, ferroptosis can be induced by the inhibition of glutathione peroxidase 4 (GPX4) or the disruption of glutathione synthesis; iron accumulation can exacerbate this process [10]. Researchers have shown that iron levels were increased in the brain tissue of neonatal HIBD patients [11]. In addition, some studies have shown that the prognosis of HIBD may be improved by desferrioxamine and erythropoietin, which modulate iron metabolism [12,13]. ...
Hypoxic-ischemic encephalopathy is the main cause of infant brain damage, perinatal death, and chronic neonatal disability worldwide. Ferroptosis is a new form of cell death that is closely related to hypoxia-induced brain damage. N-Acetyl serotonin (NAS) exerts neuroprotective effects, but its effects and underlying mechanisms in hypoxia-induced brain damage remain unclear. In the present study, 5-day-old neonatal Sprague–Dawley rats were exposed to hypoxia for 7 days to establish a hypoxia model. Histochemical staining was used to measure the effects of hypoxia on the rat hippocampus. The hippocampal tissue in the hypoxia group showed significant atrophy. Hypoxia significantly increased the levels of prostaglandin-endoperoxide synthase 2 (PTGS2) and the iron metabolism-related protein transferrin receptor 1 (TfR1) and decreased the levels of glutathione peroxidase 4 (GPX4). These changes resulted in mitochondrial damage, causing neuronal ferroptosis in the hippocampus. More importantly, NAS may improve mitochondrial function and alleviate downstream ferroptosis and damage to the hippocampus following hypoxia. In conclusion, we found that NAS could suppress neuronal ferroptosis in the hippocampus following hypoxic brain injury. These discoveries highlight the potential use of NAS as a treatment for neuronal damage through the suppression of ferroptosis, suggesting new treatment strategies for hypoxia-induced brain damage.
... WMI Model. As described in the study by Wang et al. [22], the experimental WMI model in newborn SD rats was induced using the hypoxic-ischemic method or sham operation. Briefly, SD rats at P3 were anesthetized with isoflurane and were fixed on the operating table in a supine position, and the neck skin was disinfected with 75% alcohol. ...
Hypoxic-ischemic white matter injury (WMI) pathogenesis in preterm infants is not well established, and iron-related proteins in the brain may play an important role in imbalanced iron metabolism. We aimed to investigate the iron-related protein changes in neonatal rats after hypoxia-ischemia (HI), clarify the role of iron-related proteins in hypoxic-ischemic WMI, and potentially provide a new target for the clinical treatment of hypoxic-ischemic WMI in preterm infants. We adopted a WMI animal model of bilateral common carotid artery electrocoagulation combined with hypoxia in neonatal 3-day-old Sprague-Dawley rats. We observed basic myelin protein (MBP) and iron-related protein expression in the brain (ferritin, transferrin receptor [TfR], and membrane iron transporter 1 [FPN1]) via Western blot and double immunofluorescence staining. The expression of MBP in the WMI group was significantly downregulated on postoperative days (PODs) 14, 28, and 56. Ferritin levels were significantly increased on PODs 3, 7, 14, and 28 and were most significant on POD 28, returning to the sham group level on POD 56. FPN1 levels were significantly increased on PODs 7, 28, and 56 and were still higher than those in the sham group on POD 56. TfR expression was significantly upregulated on PODs 1, 7, and 28 and returned to the sham group level on POD 56. Immunofluorescence staining showed that ferritin, TfR, and FPN1 were expressed in neurons, blood vessels, and oligodendrocytes in the cortex and corpus callosum on POD 28. Compared with the sham group, the immune-positive markers of three proteins in the WMI group were significantly increased. The expression of iron-related proteins in the brain (ferritin, FPN1, and TfR) showed spatiotemporal dynamic changes and may play an important role in hypoxic-ischemic WMI.
... As a type of cell death, ferroptosis can be induced by the inhibition of glutathione peroxidase 4 (GPX4) or the disruption of glutathione (GSH) synthesis; iron accumulation can exacerbate this process [10] . Researchers have shown that iron levels were increased in the brain tissue of neonatal HIBD patients [11] . In addition, some studies have shown that the prognosis of HIBD may be improved by desferrioxamine and erythropoietin, which modulate iron metabolism [12,13] . ...
Hypoxic-ischemic (HI) encephalopathy is the main cause of infant brain damage, perinatal death, and chronic neonatal disability worldwide. Ferroptosis is a new form of cell death that is closely related to hypoxia-induced brain damage. N-acetyl serotonin (NAS) exerts neuroprotective effects, but its effects and underlying mechanisms in hypoxia-induced brain damage remain unclear. In the present study, 5-day-old neonatal Sprague–Dawley rats were exposed to hypoxia for 7 days to establish a hypoxia model. Histochemical staining was used to measure the effects of hypoxia on the rat hippocampus. The hippocampal tissue in the hypoxia group showed significant atrophy. Hypoxia significantly increased the levels of prostaglandin-endoperoxide synthase 2 (PTGS2) and the iron metabolism-related protein transferrin receptor 1 (TfR1) and decreased the levels of glutathione peroxidase 4 (GPX4). These changes resulted in mitochondrial damage, causing neuronal ferroptosis in the hippocampus. More importantly, NAS may improve mitochondrial function and alleviate downstream ferroptosis and damage to the hippocampus following hypoxia. In conclusion, we found that NAS could suppress neuronal ferroptosis in the hippocampus following hypoxic brain injury. These discoveries highlight the potential use of NAS as a treatment for neuronal damage through the suppression of ferroptosis, suggesting new treatment strategies for hypoxia-induced brain damage.
... In patients with Alzheimer's disease, Parkinson's disease, Huntington's disease, motor neuron disease, and multiple sclerosis, elevated lipid peroxidation and iron accumulation levels have been detected in brain tissue and body fluids (Chen et al., 2013;Skouta et al., 2014;Weiland et al., 2019). Researchers discovered enhanced iron levels in HIBD brain tissues of neonatal patients (Wang et al., 2016), and desferrioxamine and erythropoietin may improve the prognosis of HIBD by modulating iron metabolism (Guardia Clausi et al., 2016;Xu et al., 2016;Huang et al., 2019). Inhibition of Toll-like receptor 4 decreased the activation of ferroptosis, attenuated oxidative stressinduced damage and neuroinflammation following HIBD (Zhu et al., 2021). ...
Ferroptosis is an iron-dependent form of regulated cell death, which is driven by loss of activity of the lipid repair enzyme glutathione peroxidase 4 (GPX4) and subsequent accumulation of lipid peroxidation. Ferroptosis is implicated in various diseases involving neuronal injury. However, the role of ferroptosis in hypoxic-ischemic brain damage (HIBD) has not been elucidated. The objectives of this study were to evaluate whether ferroptosis is involved in hypoxic-ischemic brain damage and its mechanisms through the HIBD model. A 7-day-old male Sprague-Dawley neonatal rat HIBD model was established by blocking the left common carotid artery. Laser speckle contrast imaging, immunohistochemical staining, transmission electron microscopy were used to measure the effects of ferroptosis on HIBD. Brain tissue on the damaged side in the HIBD group showed atrophied, even liquefied, glial cells increased, and blood perfusion was significantly reduced. The HIBD group insult significantly increased reactive oxygen species levels, as well as the protein levels of iron metabolism-related proteins transferrin receptor (TFRC), ferritin heavy chain (FHC), and ferritin light chain (FLC), while reducing the levels of Solute Carrier Family 7 Member 11 (SLC7A11), glutathione (GSH), and GPX4. These changes resulted in diminished cellular antioxidant capacity and mitochondrial damage, causing neuronal ferroptosis in the cerebral cortex. We conclude that ferroptosis plays a role in HIBD in neonatal rats. Ferroptosis-related mechanisms such as abnormalities in iron metabolism, amino acid metabolism, and lipid peroxidation regulation play important roles in HIBD.
Background:
White matter injury (WMI) is an important type of preterm brain injury, which may result in severe neurological sequelae and lack of effective treatments. It is ascertained that selective vulnerability of oligodendrocytes is closely related to the WMI in preterm infants. But the alteration of the endogenous oligodendrogenesis over long time after hypoxic-ischemic WMI is still not clearly elucidated.
Methods:
We adopted an animal model of hypoxic-ischemic WMI in 3-day-old neonatal Sprague-Dawley rats. Immunofluorescence staining and western blotting were used to detect dynamic changes of oligodendrogenesis in the white matter region on postoperative day (POD) 1, 3, 7, 14, 28, 56 and 84.
Results:
In the sham group, the oligodendrocyte lineage in the white matter reached a developmental peak from POD 3 to 14. The proliferation and development of oligodendrocyte precursor cells (OPCs) occurred primarily within POD 14. The number of mature oligodendrocytes showed an upward trend and a dynamic change in proliferation over time. While in the WMI group, the oligodendrocyte lineage was upregulated on POD1 and 3 but downregulated on POD 7 and 14. The proliferation of OPCs increased on POD 1 and decreased on POD 3 and 7, with the total number of OPCs significantly reduced from POD 3 to 14. The number of mature oligodendrocytes decreased from POD 3 to 28, and return to the level of the sham group on POD 56 and 84, whereas the MBP expression was still significantly downregulated on POD 56 and 84.
Conclusions:
Hypoxia-ischemia can have a long-term dynamic effect on the endogenous oligodendrogenesis of neonatal rat brain white matter. The proliferation of OPCs was promoted on POD 1 but inhibited from POD 3 to 14, which may be an early intervention target to improve oligodendrogenesis. The number of mature oligodendrocytes recover to the normal on POD 56 and 84 but the myelination is still blocked, which suggests it is essential to promote the maturation of oligodendrocyte and its function recovery at the same time within POD 28. Such efforts will provide the opportunity to test new interventions in pre-clinical studies for their promising clinical application.
Objectives
The pathogenesis of hypoxic-ischemic white matter injury (WMI) in premature infants is still unclear, and the imbalance of cerebral iron metabolism may play an important role. Our study set out to investigate the changes in iron distribution, iron content and malondialdehyde (MDA) in disparate brain regions (parietal cortex, corpus callosum, hippocampus) within 84 days after hypoxia-ischemia (HI) in neonatal rats and to clarify the role of iron metabolism in WMI.
Materials and Methods
We adopted a rat model of hypoxic-ischemic WMI. Alterations in iron metabolism were detected by iron staining and iron assay kits, and the degree of brain injury was determined by MDA assays.
Results
Our results showed that different degrees of brain iron deposition occurred within 28 days after HI, and iron staining was the most obvious 3 days after HI. The iron content increased remarkably at 1–7 d after HI in the mixed tissues, especially at 3 d after HI. While the iron content in the parietal cortex and corpus callosum elevated obviously 14 days after HI. And the change trend of MDA was almost consistent with that of the iron content.
Conclusions
Our findings revealed that brain iron metabolism changed dynamically in 3-day-old neonatal rats suffering from HI, which may cause lipid peroxidation damage to brain tissues. This process may be one of the pathogeneses of hypoxic-ischemic WMI.
Objectives:
Neuronal damage is an important pathological mechanism in neonatal hypoxic-ischemic brain damage (HIBD). We found in our previous studies that oligodendrocyte transcription factor 2 (Olig2) downregulation was able to increase cell survival in the brain. However, the specific mechanism has yet to be clarified.
Methods:
Sprague-Dawley rats aged 3 d were randomly divided into three groups: the normal control group, the Olig2-RNAi group, and the RNAi-negative control group. The normal control group received no treatment, the Olig2-RNAi group received the Olig2 RNAi adenovirus, and the RNAi-negative control group was given the control adenovirus after the completion of the HIBD model. Infarct lesions and their volumes were observed by triphenyltetrazolium chloride (TTC) staining 3 d after the completion of the adenovirus local injection. The condition of the tissue was characterized by hematoxylin-eosin staining 7 d after the model was established, and cell viability was determined by azure methylene blue staining. Subcellular damage was analyzed by transmission electron microscopy. Rotarod analysis was performed to detect moving behavior ability and an MWM assay was conducted to evaluate the memory.
Results:
TTC staining showed a smaller brain injury area in the Olig2-RNAi group than in the RNAi-negative control group. Hematoxylin-eosin staining indicated the presence of severe cell injury in the hippocampal region after HIBD, which improved after Olig2 knockdown. Azure methylene blue staining and electron microscopy results suggested that the cells improved after Olig2 knockdown. The rats stayed longer on the rotating rod, and their latency in the water maze test was gradually shortened relative to that of the rats in the Olig2-RNAi negative control group.
Conclusion:
Olig2 knockdown can promote the repair of hypoxic-ischemic brain damage in newborn rats.
