RESUMEN
Hypoxic-ischemic encephalopathy, which predisposes to neonatal death and neurological sequelae, has a high morbidity, but there is still a lack of effective prevention and treatment in clinical practice. To better understand the pathophysiological mechanism underlying hypoxic-ischemic encephalopathy, in this study we compared hypoxic-ischemic reperfusion brain injury and simple hypoxic-ischemic brain injury in neonatal rats. First, based on the conventional Rice-Vannucci model of hypoxic-ischemic encephalopathy, we established a rat model of hypoxic-ischemic reperfusion brain injury by creating a common carotid artery muscle bridge. Then we performed tandem mass tag-based proteomic analysis to identify differentially expressed proteins between the hypoxic-ischemic reperfusion brain injury model and the conventional Rice-Vannucci model and found that the majority were mitochondrial proteins. We also performed transmission electron microscopy and found typical characteristics of ferroptosis, including mitochondrial shrinkage, ruptured mitochondrial membranes, and reduced or absent mitochondrial cristae. Further, both rat models showed high levels of glial fibrillary acidic protein and low levels of myelin basic protein, which are biological indicators of hypoxic-ischemic brain injury and indicate similar degrees of damage. Finally, we found that ferroptosis-related Ferritin (Fth1) and glutathione peroxidase 4 were expressed at higher levels in the brain tissue of rats with hypoxic-ischemic reperfusion brain injury than in rats with simple hypoxic-ischemic brain injury. Based on these results, it appears that the rat model of hypoxic-ischemic reperfusion brain injury is more closely related to the pathophysiology of clinical reperfusion. Reperfusion not only aggravates hypoxic-ischemic brain injury but also activates the anti-ferroptosis system.
RESUMEN
Hypoxic-ischemic encephalopathy (HIE) is detrimental to newborns and is associated with high mortality and poor prognosis. Thus, the primary aim of the present study was to determine whether glycine could (1) attenuate HIE injury in rats and hypoxic stress in PC12 cells and (2) downregulate mitochondria-mediated autophagy dependent on the adenosine monophosphate- (AMP-) activated protein kinase (AMPK) pathway. Experiments conducted using an in vivo HIE animal model and in vitro hypoxic stress to PC12 cells revealed that intense autophagy associated with mitochondrial function occurred during in vivo HIE injury and in vitro hypoxic stress. However, glycine treatment effectively attenuated mitochondria-mediated autophagy. Additionally, after identifying alterations in proteins within the AMPK pathway in rats and PC12 cells following glycine treatment, cyclosporin A (CsA) and 5-aminoimidazole-4-carboxamide-1-b-4-ribofuranoside (AICAR) were administered in these models and indicated that glycine protected against HIE and CoCl2 injury by downregulating mitochondria-mediated autophagy that was dependent on the AMPK pathway. Overall, glycine attenuated hypoxic-ischemic injury in neurons via reductions in mitochondria-mediated autophagy through the AMPK pathway both in vitro and in vivo.
