目的:探讨缺血后适应对大鼠局灶性脑缺血再灌注所致自噬的影响.方法:取健康雄性SD大鼠30只,随机分为假手术(sham)组、缺血再灌注(I/R)组、缺血后适应(IPC)组,每组各10只.Sham组仅单纯暴露右侧颈总、颈内和颈外动脉;I/R组采用Longa改良线栓法制备大鼠右侧大脑中动脉缺血2 h、再灌注24 h模型;IPC组大鼠缺血2 h后,同侧颈总动脉再通10 s/闭塞10 s,循环5次,然后全面恢复血流再灌注24 h.采用透射电镜观察脑细胞自噬情况;Western blot法测定各组大鼠脑组织中哺乳动物雷帕霉素靶蛋白(mTOR)、磷酸化mTOR(p-mTOR)和微管相关蛋白轻链3(LC3)-Ⅱ的蛋白表达水平;TTC法检测脑梗死面积;干湿称重法测定脑组织含水量;HE染色观察脑组织病理学变化.结果:IPC组mTOR、p-mTOR均显著高于I/R组(P<0.05),LC3-Ⅱ显著低于I/R组(P<0.01).IPC组脑梗死面积、脑组织含水量均显著低于I/R组(P<0.01).HE染色显示,IPC组神经元变性、坏死较I/R组明显减轻.透射电镜显示IPC组神经元损伤程度明显减轻,自噬泡明显减少.结论:IPC通过减少细胞内自噬而减轻脑缺血再灌注损伤,可能与增强mTOR作用有关.%AIM:To investigate the effect of ischemic postconditioning ( IPC) on autophagy induced by focal cerebral ischemia reperfusion ( I/R) in rats.METHODS:Healthy male SD rats were assigned randomly into sham-opera-tion (sham) group, I/R group and IPC group with 10 rats in each group.The rats in sham group were only exposed the right common , internal and external carotid artery surgically .The rats in I/R group were subjected to right middle cerebral artery occlusion (MCAO) by the modified Longa suture method for 2 h followed by 24 h of reperfusion.The rats in IPC group were subjected to MCAO for 2 h followed by reperfusion of the ipsilateral common carotid artery occlusion for 10 s for 5 episodes, and then reperfusion for 24 h.Autophagy was obeserved by transmission electron microscopy (TEM).The pro-tein levels of mammalian target of rapamycin (mTOR), p-mTOR and microtubule associated protein light chain 3 (LC3)-II in brain tissue of the rats were determined by Western blot .Pathological changes of brain tissue were observed by HE staining.RESULTS:The protein levels of mTOR and p-mTOR in IPC group were significantly higher than those in I/R group (P<0.05).The expression of LC3-II in IPC group was significantly lower than that in I/R group (P<0.01).The cerebral infarction area and brain water content in IPC group were significantly lower than those in I /R group (P<0.01). HE staining showed that neurons degeneration and necrosis in IPC group were significantly alleviated compared with I /R group.TEM observation showed that IPC revealed fewer autophagosomes , with much less severe cell damage than that in I/R group.CONCLUSION:IPC reduces brain ischemia reperfusion damage by decreasing autophagy of brain cells , which might be related to the activation of mTOR .
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