PI3K-mTOR信号通路对蛛网膜下腔出血大鼠海马区神经细胞自噬的调控作用

摘要

目的 探讨PI3K-mTOR信号通路对蛛网膜下腔出血(subarachnoid hemorrhage,SAH)大鼠海马区神经细胞自噬的调控作用.方法 成年雄性Sprague-Dawley大鼠随机分为假手术组(n=24)、蛛网膜下腔出血模型组(SAH组,n=24)和LY294002组(n=24).采用二次注血法制作SAH模型,假手术组不注血,LY294002组于造模前30 min应用PI3K特异性抑制剂LY294002侧脑室注射,对SAH大鼠进行预处理,注射剂量为500μmol/只.分别在出血后6、24、72、144 h HE染色观察海马CA1区神经细胞形态结构变化;免疫组化对PI3K、mTOR及Beclin-1和LC3-Ⅱ蛋白表达水平进行检测.结果 SAH大鼠海马CA1区神经元数量明显少于对照组(P<0.05),PI3K-mTOR信号通路明显被激活,自噬相关因子Beclin-1和LC3-Ⅱ的表达高于对照组(P<0.05);LY294002组各时间点海马CA1区神经元数量明显较SAH组减少(P<0.05),PI3K-mTOR信号通路被抑制,相应自噬相关因子Beclin-1和LC3-Ⅱ的表达降低(P<0.05).结论 PI3K-mTOR信号通路通过激活神经细胞自噬参与SAH后的细胞保护.%Objective To explore the regulation of PI3K-mTOR signaling pathways on autophagy of hippocampus nerve cells after subarachnoid hemorrhage (SAH)in rats.Methods We randomly divided 72 male Sprague-Dawley rats into sham group,SAH model group and LY294002 group with 24 rats in each group.We established SAH model with the secondary injection of blood method while the sham group was not injected with blood.PI3K signaling pathways specific inhibitor LY294002 was injected with 500μmol per rat 30 minutes before modeling.After 6,24,72 and 144 h morphologic changes of hippocampus CA1 neural cells were observed by microscopy;the expression levels of PI3K,mTOR,Beclin-1 and LC3-Ⅱ were detected by immunohistochemical method.Results The density of survival neurons in the SAH group was significantly lower than that in the control group (P<0.05),PI3K-mTOR signaling pathways were activated obviously,and the expressions of Beclin 1 and LC3-Ⅱ were significantly higher than those in the control group (P<0.05 ).The number of survival neurons significantly decreased in the LY294002 group compared with the SAH group at each time point (P<0.05),PI3K-mTOR signaling pathways were suppressed.The expressions of Beclin-1 and LC3-Ⅱ were significantly lower than those in the SAH group (P<0.05).Conclusion PI3K-mTOR signaling pathways protect neurons by activating the autophagy of neurons after SAH.