自噬在小鼠脑缺血再灌注损伤中的作用

The role of autophagy in cerebral ischemia and reperfusion injury

目的 观察自噬在小鼠脑缺血再灌注损伤中的作用.方法 建立小鼠局灶性脑缺血再灌注模型,Western blot法和免疫荧光法检测自噬相关蛋白表达,红四氮唑（TTC）染色法检测抑制自噬对缺血再灌注损伤后脑梗死面积的影响,Longa法检测抑制自噬对缺血再灌注损伤后神经症状评分的影响.结果 Western blot结果显示,再灌注后损伤缺血皮层的微管相关蛋白1轻链3（LC3）-Ⅱ/LC3-Ⅰ比值、Beclin-1蛋白表达水平明显增加,呈时间依赖性,12h达到高峰.免疫荧光法显示,缺血再灌注后6h及12 h神经元胞质内点状荧光颗粒表达逐渐增强.给予3-甲基腺嘌呤（3-MA）能显著降低缺血皮层的LC3-Ⅱ/LC3-Ⅰ比值,减少脑梗死面积,并减轻神经行为学损伤（P＜0.05）.结论 脑缺血再灌注损伤后自噬的过度激活可能促进神经元的死亡.

Objective To study the role of autophagy in cerebral ischemia and reperfusion injury.Methods Focal cerebral ischemia and reperfusion models were induced using the suture occlusion technique.Western blotting was employed to determine alternation in microtubule-associated protein 1 light chain 3 （LC3） and Beclin-1 levels in ischemic cortex at 0 h,6 h,12 h,and 24 h after reperfusion,and alternations in LC3 level 24 h after 3-methyladenine （3-MA） administrated.Infarct volume was evaluated by TTC staining,and motor deficits were evaluated by Longa five-point method.Results The expression of autophagic-related protein in ischemic cortex such as LC3-Ⅱ and Beclin-1 increased significantly after cerebral ischemia and reperfusion injury,with a maximal induction at 12 h.Furthermore,increased punctuate LC3 labeling occurred in neurons from 6 h and 12 h.Autophagic inhibitor 3-MA decreased LC3-Ⅱ levels,reduced the infarct volume and ameliorated the neurological symptoms （P ＜ 0.05）.Conclusion Autophagy plays a pro-death role in cerebral ischemia and reperfusion injury.