PI3K/PKB信号途径在远程肢体缺血后处理减轻脑缺血再灌注损伤中的作用

Effects of PI3K/PKB Signal Transduction Pathway in Limb Ischemic Postconditioning against Cerebral Ischemia Reperfusion Injury

目的:通过观察肢体缺血后处理(LIP)后p-Akt、Caspase-9及Bcl-2蛋白的表达,探讨PI3K/PKB信号途径在远程LIP减轻脑缺血再灌注损伤中的作用。方法:42只大鼠随机分成对照组、缺血再灌注(IR)组和LIP组各14只,后2组采用线栓法制备局灶性脑缺血再灌注模型,LIP组在缺血2 h后再灌注前实施3个循环健侧股动脉缺血5 min再灌注5 min的LIP。采用TTC染色测定脑梗死体积,免疫组化法检测p-Akt、Caspase-9、Bcl-2蛋白的表达。结果:LIP组大鼠脑梗死体积较IR组明显减小(P<0.05)。LIP组p-Akt、Bcl-2蛋白表达较IR组明显增高(P<0.05),LIP组Caspase-9蛋白表达较IR组明显降低(P<0.05)。结论:LIP可上调p-Akt、Bcl-2表达,下调Caspase-9表达,并减轻脑梗死体积,PI3K/PKB信号通路在LIP减轻脑缺血再灌注损伤中可能发挥重要保护作用。

Objective:To investigate the changes in expression of p-Akt,Caspase-9,and Bcl-2 protein in the rat model of limb ischemic postconditioning(LIP)and examine the effect of the phosphatidylinositol 3-kinase/Protein Kinase B(PI3K/PKB)signal transduction pathway in LIP against cerebral ischemia reperfusion injury in rats.Methods:A total of 42 Wistar rats were randomly assigned to the sham surgery group,ischemia/reperfusion(IR)group,and LIP group with 14 rats in each group.The filament occlusion method was employed to generate the focal cerebral ischemia reperfusion model in the latter two groups.Two hours after the middle cerebral artery occlusion model was established and before reperfusion,LIP was carried out in LIP group rats by three cycles of 5 minutes occlusion/5 minutes release of the left femoral artery.Brain sections were stained with TTC for surveying the volume of infraction.The expression of p-Akt,Caspase-9,and Bcl-2 proteins was determined by immunohistochemical staining.Results:Compared with the IR group,the LIP group showed significantly decreased infarct volume(P<0.05).The expression of p-Akt protein and Bcl-2 protein significantly increased in the LIP group compared with that in the IR group(P<0.05).The expression of caspase-9 protein significantly decreased in the LIP group compared with that in the IR group(P<0.05).Conclusion:Limb ischemic postconditioning may upregulate the expression of p-Akt and Bcl-2 proteins,downregulate the expression of caspase-9 protein,and reduce the cerebral infarct volume.The PI3K/PKB signal transduction pathway may play important roles in limb ischemic postconditioning against cerebral ischemia reperfusion injury.