线粒体通透性转换孔在缺血预处理脑保护中的作用及机制

Role of mitochondrial permeability transition pore in cerebral protection induced by ischemic preconditioning and its mechanism

目的观察线粒体通透性转换孔(mitochondrial permeability transition pore,MPTP)在缺血再灌注及缺血预处理脑保护中的作用。方法将体外培养8 d的海马神经元分为五组,正常对照组(A组),缺血再灌注组(B组),缺血预处理+缺血再灌注组(C组),苍术苷+缺血再灌注组(D组),缺血预处理+苍术苷+缺血再灌注组(E组)。使用流式细胞术检测各组细胞凋亡率,罗丹明123染色流式细胞术检测线粒体膜电位,Western-blot检测Bcl-2,Bax的表达水平。结果与A组比较,其余四组线粒体膜电位均降低,神经元凋亡率升高(P<0.05);与B组比较,C组线粒体膜电位升高,神经元凋亡率升高,Bcl-2表达上调,Bax表达下调(P<0.05);与C组比较,E组粒体膜电位降低,神经元凋亡率升高,Bcl-2表达下调,Bax表达上调(P<0.05)。结论缺血预处理能有效减轻海马神经元缺血再灌注损伤,抑制缺血再灌注后神经细胞凋亡,其机制可能与抑制MPTP的开放有关。

Objective To explore the role of mitochondrial permeability transition pore（MPTP） in cere- bral ischemia/ reperfusion and ischemic preconditioning. Methods The hippocampal neurons of newborn Wistar rats were primaryly cultured for 8 days and randomly divided into five groups： Control group （group A）, ischemic reperfusion group（group B）, ischemic preconditioning ＋ ischemia/reperfusion group（group C）, atractyloside＋ ischemia/reperfusion group（group D）and ischemic preconditioning ＋ atractyloside ＋ ischemia/ reperfusion group（group E）. The rates of neuronal apoptosis in each group were measured by flow eytometry, and the mitochondrial membrane potentials were detected by flow cytometry through Rhodamine 123 staining. Western bolt was adopted to investigate the expressions of Bcl-2 and Bax in these groups. Results Compared with Group A, the mitocbondrial membrane potential of other groups reduced, whereas the percentage of neu-ronal apoptosis increased significantly （P〈0. 05）. Compared with group B, the mitochondrial membrane po-tential increased and the neuronal apoptosis decreased significantly in group C （P〈0. 05）. According to the resuits of western bolt, the expression of Bcl-2 in this group increased （P〈0. 05）, while Bax decreased （P〈 0. 05）. Compared with group C, the mitochondrial membrane potential decreased and the neuronal apoptotic rate increased in group E （P〈0. 05）. And the expression of Bcl-2 down-regulated, while Bax up-regulated （P〈0. 05）. Conclusions Ischemic preconditioning decreases the neuronal apoptosis induced by an ischemia/ reperfusion injury in cultured hippocampal neurons, which is related to the inhibition of the MPTP.