Akt信号途径参与二氮嗪预处理抑制缺氧复氧损伤大鼠海马神经元的凋亡

目的 探讨二氮嗪(DZ)预处理能否通过上调Akt信号增强Bcl-2表达、抑制Bax表达发挥抗凋亡作用.方法 离体培养9～10 d SD大鼠海马神经元分为正常对照组(A组)、缺氧组(B组)、缺氧+DZ 100 μmol/L组(c组)、缺氧+DZ 100 μmol/L+5-羟癸酸100 μmol/L组(D组)、缺氧+DZ 100 μmol/L+LY294002 50 μmol/L组(E组),自缺氧前2 d开始,神经元接受DZ预处理,每天1次,每次1 h.每次实验,每组16孔或2皿细胞,实验重复3次.比较缺氧4 h复氧48 h各组海马神经元的活力、凋亡率、Akt、Bcl-2和Bax蛋白的表达程度.结果 缺氧复氧后C组吸光度值较B、D、E组显著增高(P＜0.05);其他缺氧各组间比较,差异无统计学意义(P＞0.05).C组凋亡率较B、D、E组显著减低(P＜0.05).C组Akt、Bcl-2表达较B、D、E组强烈(P＜0.05),Bax表达则减弱(P＜0.05).B、D、E组问比较,差异无统计学意义(P＞0.05).结论 DZ可经Akt信号通路上调Bcl-2/Bax蛋白比值而抑制缺氧复氧损伤大鼠海马神经元的凋亡.

Akt involved in diazoxide preconditioning against rat hippocampal neuronal apoptosis induced by anoxia-reoxygenation injury

Objective Investigate whether preconditioning with diazoxide(DZ),a mitochondrial ATP-sensitive potassium channel opener,could enhance Akt protein to up-regulate Bcl-2/Bax protein ratio against apoptosis.Methods Cultured for 9-10 d in vitro,the hippocampat neurons of Sprague-Dawley rats were assigned to the following 5 groups randomly:Control(Group A),Anoxia(Group B),Anoxia+DZ100 μmoL/L(Group C),Anoxia+DZ100 μmol/L+5-hydroxydecanoate(Group D),Anoxia+DZ100 μmol/L+LY294002 50 μmol/L(Group E).Prior to oxygen deprivation,the hippocampal neurons were treated with DZ for 1 h per day and this treatment was persisted for 3 d.Each experiment was repeated for three times and each group contained 16 wells or 2 dishes of neurons for each time.Thereafter,neurons were derived of oxygen for 4 h.At 48 h of reoxygenation the neuronal optical density(A)were measured by MTT method,while the apoptotic rates were assayed by annexin V-FITC staining.The expressions of Akt,Bcl-2 and Bax proteins were detected and evaluated by Western blot.Results Compared with other pretreatment,DZ 100 μmoL/L led to the elevation of A,whereas promoted the decrease of apoptotic rate(P ＜ 0.05).Compared with those in other anoxic groups,the expressions of Akt protein and Bcl-2 protein in Group C were increased significantly(P ＜0.05),whereas the Bax density were reduced significantly(P ＜ 0.05).Preceding administration of 100 μmol/L DZ took protective effects on the neurons induced by anoxia-reoxygenation.Conclusions DZ 100 μmol/L increased Akt protein to up-regulate Bcl-2/Bax protein ratio against apoptosis induced by anoxia-reoxygenation.