电针对脑缺血再灌注大鼠大脑皮层去甲肾上腺素及细胞凋亡的影响

目的:探讨电针对脑缺血再灌注神经元保护的作用及其机制。方法:SD大鼠随机分为对照组、缺血再灌注组及电针组,以双侧颈总动脉夹闭方法建立脑缺血模型,用流式细胞仪检测细胞凋亡和Bcl-2及Bax蛋白表达的变化,并用荧光分光法检测皮层去甲肾上腺素(norepinephrine,NE)含量的变化。电针穴位选择“水沟”“承浆”穴。结果:①大鼠脑缺血再灌注48 h后,细胞凋亡率明显高于对照组(P<0.05),Bcl-2蛋白表达在皮层明显降低,Bax/Bcl-2比值较对照组明显升高(P<0.05);电针治疗后,Bax的表达减少,Bcl-2的表达增加,Bax/Bcl-2比值明显下降(P<0.05),细胞凋亡率受到抑制(P<0.05)。②大鼠脑缺血再灌注3 min后NE含量在皮层明显升高,与对照组相比有显著性差异(P<0.05);脑缺血再灌注48 h后,皮层NE含量明显回落,与对照组相比无显著性差异;电针治疗后,脑缺血再灌注早期(即缺血再灌3 min后)脑组织内NE升高的现象出现逆转,与模型组比较有显著性差异(P<0.05)。结论:脑缺血再灌注早期大鼠脑NE出现变化,此变化可能与神经元的凋亡发生有关。电针能逆转脑缺血再灌导致的NE的异常变化,并调节Bax/Bcl-2的表达水平,抑制神经元凋亡的发生。

Effect of Electroacupuncture on NE and Neuronal Apoptosis in the Cerebral Cortex in Rats with Cerebral Ischemia-reperfusion

Objective: To investigate the underlying neurobiological mechanism of the protective effect of electroacupuncture(EA) on cerebral neurons during cerebral ischemia and reperfusion(CI/R).Methods: Fifteen SD rats were evenly randomized into control,model(CI/R 48 h) and EA groups.CI/R model was established by occlusion of the bilateral carotid arteries and reperfusion.The neuronal apoptosis and expression of Bcl-2 and Bax proteins of the cerebral cortex in each group were detected by flow cytometer.Additionally,other 75 SD rats were evenly randomized into control,CI/R-3 min,CI/R-3 min+EA,CI/R-48 h and CI/R-48 h+EA groups.NE concentration of cerebral cortex was detected by fluorescence spectrometer.EA(4-16 Hz,1-3 V) was applied to "Shuigou"(GV 26) and "Chengjiang"(RN 24) for 30 min before CI/R.Results: In comparison with control group,the number of neurons in the cerebral cortex in phase sub-G_1 and the apoptotic rate in CI/R-48 h group were significantly higher(P<0.05);while comparison between CI/R-48 h and CI/R-48 h+EA groups showed that both the number of neurons in phase sub-G_1 and the apoptotic rate of the later group were significantly lower than those of CI/R-48 h group(P<(0.05),) suggesting that EA could effectively suppress neuronal apoptosis induced by CI/R.Compared with control group,the expression of Bcl-2 of CI/R-48 h group decreased significantly,while that of Bax and Bax/Bcl-2 in CI/R-48 h group increased considerably(P<0.05).Comparison between CI/R-48 h and CI/R-48 h+EA groups showed that the expression of Bcl-2 of the later group was markedly higher and that of Bax and Bax/Bcl-2 was significantly lower in the later group than that in the former group(P<0.05),suggesting that EA could evidently suppress CI/R induced up-regulation of Bax and down-regulation of Bcl-2 expression.Besides,in comparison with control group,the concentration of NE in cerebral cortex of CI/R-3 min group was significantly higher(P<0.05);while that of CI/R-3 min+EA group was significantly lower than that of CI/R-3 min group(P<0.05),showing that EA could considerably inhibit CI/R induced increase of cerebral cortex NE level.No significant changes were found in the cerebral NE levels in CI/R-48 h and CI/R-48 h+EA groups.Conclusion: EA can suppress CI/R induced neuronal apoptosis which may be related to its favorable regulation on Bax and Bcl-2 expression and suppression of NE release in the cerebral cortex in CI/R rats.