脑缺血再灌注不同时间对大鼠海马神经元自噬及PI3K/mTOR通路的影响

目的：探讨脑缺血再灌注不同时间对大鼠海马神经元自噬及PI3K/mTOR通路的影响。方法：72只大鼠随机分为假手术组、脑缺血再灌注组（分别再灌0、6、12、24、36 h），每组12只。采用四血管阻断法建立大鼠全脑缺血再灌注损伤模型。神经功能缺损评分评价大鼠海马神经功能，HE染色检测大鼠海马神经细胞损伤，透射电镜下观察海马神经元内自噬小体，Western blot检测Beclin-1、LC3 II、p62、p-PI3K、p-Akt及p-mTOR蛋白表达。结果：与假手术组比，随着脑缺血再灌注的时间延长，脑缺血再灌注大鼠神经功能缺损评分、脑梗死面积、自噬小体数量均增加（均P＜0.05）；随着脑缺血再灌注的时间延长，大鼠海马组织自噬相关蛋白Beclin-1和LC3 II表达显著上调、p62表达下调（P＜0.05）；PI3K/mTOR通路相关蛋白p-PI3K、p-Akt、p-mTOR表达显著下调（P＜0.05）。结论：脑缺血再灌注可增强大鼠海马神经元自噬，抑制PI3K/mTOR信号通路。

The effect of cerebral ischemia reperfusion in different time on autophagy of hippocampal neurons and PI3K/mTOR pathway in rats

Objective: To investigate the effect of cerebral ischemia reperfusion in different time on autophagy of hippocampal neurons and PI3K/mTOR pathway in rats. Methods: Totally 72 rats were randomly divided into sham operation group and cerebral ischemia reperfusion groups (reperfusion for 0 h, 6 h, 12 h, 24 h, 36 h, respectively), with 12 rats in each group. The rat model of global cerebral ischemia reperfusion injury was established by four-vessel occlusion. Modified neurological severity score was used to evaluate hippocampal neurological function in rats, HE staining was used to detect the damage of hippocampal neurons in rats, the autophagic bodies in hippocampal neurons were observed under transmission electron microscopy, Western blot was used to detect the expressions of Beclin-1, LC3 II, p62, p-PI3K, p-Akt, and p-mTOR proteins. Results: Compared with the sham operation group, the cerebral ischemia reperfusion rats showed an increase in the modified neurological severity score, cerebral infarction area, and the number of autophagosomes; the expressions of autophagy-related proteins Beclin-1 and LC3 II in hippocampus of rats were significantly up-regulated (P<0.05), the expression of p62 was significantly down-regulated (P<0.05), the expressions of PI3K/mTOR pathway related proteins p-PI3K, p-Akt, and p-mTOR were significantly down-regulated (P<0.05). With the prolongation of cerebral ischemia reperfusion time, the expressions of autophagy-related proteins Beclin-1 and LC3 II increased, the expression of p62 decreased and so did the PI3K/mTOR pathway related proteins p-PI3K, p-Akt, and p-mTOR. Conclusion: Cerebral ischemia reperfusion can enhance autophagy of hippocampal neurons and inhibit PI3K/mTOR signaling pathway in rats.