Effect of orexin-A on programmed necrosis during cerebral ischemia-reperfusion in rats / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of orexin-A on programmed necrosis during cerebral ischemia-reperfusion (I/R) in rats.Methods:Thirty clean-grade healthy adult male Spraugue-Dawley rats, weighing 280-320 g, were divided into 3 groups ( n=10 each) using a random number table method: sham operation group (Sham group), cerebral I/R group (I/R group) and orexin-A group (OA group). In I/R and OA groups, a rat model of global cerebral I/R injury was established by transesophageal cardiac pacing-induced cardiac arrest and cardiopulmonary resuscitation in anesthetized animals.Orexin-A 30 μg/kg (diluted to 0.5 ml in phosphate buffer solution) was intravenously injected at 10 min before establishing the model in OA group.Phosphate buffer solution 0.5 ml was intravenously injected at 10 min before establishing the model in Sham and I/R groups.The neurological deficit score (NDS) was assessed at 24 h of reperfusion, then the rats were sacrificed, and bilateral hippocampal tissues were obtained.The morphological structure of pyramidal cells in the hippocampal CA1 region was examined after HE staining, and normal pyramidal cells were counted.Western blot was used to detect the expression of receptor-interacting protein 1 (RIP1), RIP3 and mixed-lineage kinase domain-like protein (MLKL). Immuno-histochemistry was used to count RIP1, RIP3 and MLKL positive cells in the hippocampal CA1 region.The activity of superoxide dismutase (SOD) in hippocampi was determined by xanthine oxidase method, and the content of malondialdehyde (MDA) in hippocampi was determined by thiobarbituric acid method. Results:Compared with Sham group, the normal pyramidal cell count in the hippocampal CA1 region was significantly decreased, NDS was increased, the expression of RIP1, RIP3 and MLKL protein was up-regulated, the positive cell count was increased, the content of MDA in hippocampi was increased, and the activity of SOD in hippocampi was decreased in I/R and OA groups ( P<0.05). Compared with I/R group, the count of normal pyramidal cells in the hippocampal CA1 region was significantly increased, NDS was decreased, the expression of RIP1, RIP3 and MLKL protein was down-regulated, the count of positive cells was decreased, the content of hippocampal MDA was decreased, and the activity of hippocampal SOD was increased in OA group ( P<0.05). Conclusion:The mechanism by which orexin-A reduces cerebral I/R injury may be related to inhibiting programmed necrosis in rats.