线粒体K_(ATP)通道开放剂对多巴胺能神经细胞的保护作用研究

Effects of mitochondrial ATP-sensitive potassium channel opener on rotenone-induced cytotoxicity

目的研究线粒体KATP通道的开放对于鱼藤酮诱导的细胞凋亡的保护作用并初步探讨其机制。方法用神经生长因子(NGF)将PC12细胞诱导分化成多巴胺能神经元模型,经鱼藤酮和线粒体KATP通道的开放剂二氮嗪及选择性线粒体KATP通道拮抗剂5-羟葵酸(5-HD)处理,用台盼蓝染色和四甲基偶氮唑盐(MTT)法检测细胞活力,磷脂酰丝氨酸外翻法(Annexin V)检测细胞的凋亡,JC-1检测线粒体膜电位的变化。结果经鱼藤酮处理24h后PC12细胞突起结构消失,细胞体积变小,形态变圆,台盼蓝染色阳性细胞增多,细胞活力下降,可见An-nexin V阳性的早期凋亡细胞,凋亡率为31.1%±2.65%(P<0.01);同时加入二氮嗪能减少PC12细胞的凋亡,凋亡率为17.9%±0.71%(P<0.05);JC-1染色法证实二氮嗪可稳定线粒体膜电位。而同时加入5-HD的PC12细胞活力及线粒体膜电位与鱼藤酮处理组相比无变化。结论鱼藤酮可引起多巴胺神经元的凋亡,线粒体KATP通道的开放剂二氮嗪能够拮抗鱼藤酮的毒性作用,其机制可能是通过在线粒体膜电位降低时稳定线粒体膜电位而起到对多巴胺能细胞的保护作用。

Objective To investigate the protective effect of mitochondrial ATP-sensitive potassium channel （mitOKATP） opener on rotenone-indueed cytotoxicity. Methods PC12 cells differentiated by nerve growth factor as dopaminergic neurons were treated by rotenone alone or with mitoKATpChannel opener diazoxide and selective mitoKATP channel blocker 5-HD. Cell viability was assessed with Typan blue stain and MTT, and cell apoptosis was detected by annexin-V staining and flow cytometry. JC-1 was used to detect mitochondrial membrane potential changes. Results After treated with rotenone for 24 hours, the process of PC12 cells disappeard, and the cell body became smaller and smother. Compared with the control group, the cell viability began to decline. The early sign of apoptosis was found by Annexin-V positive staining;the apoptosis ratio was 31.1%± 2.65 % （P 〈 0. 01 ） ;when treated by diazoxide and rotenone simultaneously, the ratio was decreased to 17.9% ± 0.71% （ P 〈 0.05 ） , and the depolarization of mitochondrial membrane induced by rotenone was reversed. 5-HD, the antagonist of mitOKATP channel when opening, had opposite result to the effects caused by diazoxide. Conclusion In vitro, rotenone shoud be neurotoxic to dopaminergic neurons,inducing apoptosis. The mitoKATP channel opener diazoxide can protect PC12 cells against rotenone induced cytotoxicity. The mechanism of the protection maybe stabilized the mitochondrial membrane electric potential.