细胞色素C在糖尿病心肌病大鼠心肌细胞凋亡的作用

目的 探讨链脲佐菌素（STZ）制备的糖尿病心肌病（DCM）大鼠心肌细胞凋亡中的信号转导机制.方法 40只雄性Wistar大鼠随机分为正常对照组（CON,15只）,糖尿病心肌病组（DCM,25只）.CON组喂养标准饲料,DCM组给予高脂高糖饮食.7周后检测空腹血糖（FBG）、血浆胰岛素（INS）、胰岛素抵抗指数（ISI）,证实DCM组产生胰岛素抵抗后给予腹腔注射STZ 30mg/kg,72h后断尾取血测定FBG≥16.7mmol/L确定2型糖尿病模型成功,继续高脂高糖饮食8周后采用TUNEL法检测大鼠心肌细胞的凋亡；以比色法检测caspase8和caspase-3的相对活性；Western Blotting检测胞浆及线粒体内细胞色素C（Cyt C）漏出情况.结果 与CON组相比,6周的高脂高糖饮食后DCM组FBG无明显差异（P＞0.05）,INS及ISI均明显升高（p均＜0.01）；15周时,与CON组相比,心肌组织中凋亡指数明显升高（P＜0.01）；caspase-3活性显著升高（P＜0.01）,但caspase-8没有明显变化；糖尿病心肌病大鼠心肌细胞线粒体中Cyt C表达降低而胞浆中的表达增加.结论 糖尿病心肌病大鼠心肌中存在明显的细胞凋亡现象,细胞凋亡的机制可能与线粒体过度释放Cyt C激活caspase-3有关.

Effect of Cytochrome C on Apoptosis of Cardiac Myocytes in Rats with Diabetic Cardiomyopathy

Objective To investigate the mechanism of cytochrome C on apoptosis of cardiac myocytes in rats with STZ-induced diabetic cardiomyopathy. Methods Forty wistar rats were divided into saline control group （ CON, 15）and diabetic cardiomyopathy group（ DCM,25 ） ,group CON was fed with standard diet,but group DCM with high-fat high-sugar diet for 6w. After insulin resistance, group DCM was given intraperitoneal injection of STZ. At the end of 15w, cadiac apoptosis was evaluated by terminal deoxynucleotidy transferase mediated dUTP-biotin nick end labelling （TUNEL） assay;Caspase-3 relative activity were analyzed by color imetric assay;The change of cytochrome C was monitored with Westen Blotting. Results At the end of 7w,compared with group CON, INS and ISI in group DCM were increased ;At the end of 15w,compared with CON,the expression of cytochrome C in mitochondria of group DCM were lower, but the activity of caspase-3, CAI and the expression of cytochrome C in cytoplasm were higher, but that of caspase-8 did not change. Conclusion There are apoptosis of cardiac myocytes in rats with diabetic cardiomyopathy, for it can pro- mot the release of cytochrome C from mitochondria and then active caspase-3.