Gαi2对脑缺血-再灌注后神经细胞凋亡的影响

The effect of Gαi2 on neuronal apoptosis in cerebral ischemia-reperfusion injury model of rats

目的探讨分析抑制性G蛋白仪2亚单位（Gαi2）在大鼠脑缺血-再灌注损伤模型海马中的表达及其对神经细胞内钙离子浓度和凋亡的影响。方法将90只SD大鼠随机（随机数字法）分为假手术组（ss组，n=30）、脑缺血-再灌注损伤组（IR组，n=30）。脑缺血-再灌注且脑室内微量灌注Gαi2活性抑制剂百日咳毒素（PT）组（胛组，n=30）；用免疫组化、Westernblotting分别测定大鼠脑缺血-再灌注后6h、12h、24h各组中海马神经内Gαi2的表达，采用流式细胞术测定各组中海马细胞内游离Ca^2＋浓度的平均荧光值，TUNEL法检测神经元细胞的凋亡。结果不同时间点，IR组Gαi2含量和Ca^2＋浓度较SS组明显增高（P〈0．01），PT组Ca^2＋浓度较IR组升高（P〈0．01），PT组神经细胞凋亡率较IR组升高（P〈0．05）。结论Gαi2在大鼠脑缺血-再灌注损伤中表达明显增高，并可降低缺血神经细胞内的钙离子浓度，减少神经细胞的凋亡，对缺血神经细胞具有保护作用。

Objective To discuss the levels of inhibitory protein Gαi2 （Gcxi2） in hippocampus of brain and the effects of Gαi2 on neuronal intracellular Ca^2＋ level in cerebral ischemia reperfusion injury model of rats. Methods Ninety SD rats were randomly （ random number） assigned to sham group （ n = 30 ）, ischemic - reperfusion （IR） group （ n = 30）, Pertussis toxin （PT） group （ n = 30）. The blood flow of right common carotid artery of rat was blocked for 90 mix to make ischemia reperfusion model. The levels of Gαi2 in hippocampus was assayed by immunohistochemistry and Western blotting after ischemia reperfu - sion for 6, 12, 24 h in each group. The average fluorescence values of intracellular Ca^2＋ levels in hippocampus of rats in three groups were detected by using Flow CytoMeter （FCM）. Neuronal cell apoptosis was measured by TUNEL. Results After restoration of middle cerebral artery blood flow for different lengths of time, the levels of hippocampus God2 and Ca2 ＋ levels in IR group were significantly higher than those in Sham group （P 〈0. 01 ）. The hippocampus Ca^2＋ levels in PT group were higher than those in IR group （P 〈0. 01 ） . The apoptotic rates of neurons in PT group were lower than those in IR group （P 〈 0. 05 ）. Conclusions The level of Gαi2 in cerebral ischemia reperfusion injury model was increased. Gαi2 might reduce the calcium ion concentration of neurons after cerebral ischemia and reduce the neuronal cell apoptosis in this model. Gαi2 might play a role in protecting neuron from cerebral ischemia reperfusion