内质网应激参与调控肺心病心肌细胞线粒体途径凋亡

Endoplasmic reticulum stress is involved in the regulation of myocardial mitochondrial apoptosis in chronic cor pulmonale

目的探讨内质网应激在慢性肺源性心脏病心肌细胞线粒体凋亡途径中的作用及机制。方法24只8周龄Wistar大鼠随机分为缺氧组、干预组和对照组,每组8只。缺氧组大鼠采用常压间歇缺氧法建立肺心病模型,每天给予生理盐水灌胃;干预组大鼠同样构建肺心病模型,每天给予内质网应激抑制剂4-PBA灌胃;对照组大鼠在普通饲养笼中饲养,每天给予生理盐水灌胃。处理21 d后处死大鼠并分离右心室,TUNEL法测定右室细胞凋亡率,JC-1荧光探针检测线粒体膜电位,Western blot检测右心室心肌组织中内质网应激标志性分子葡萄糖调节蛋白78(GRP78)及抗CCAAT/增强子结合蛋白同源蛋白(CHOP)、线粒体途径凋亡相关蛋白Bcl-2和细胞色素C表达水平。结果与对照组相比,缺氧组大鼠右心室肥大、心肌细胞凋亡率明显增加(均P<0.001),CHOP、GRP78、Bcl-2、线粒体释放细胞色素C均明显增加(P≤0.001)。而与缺氧组相比,干预组大鼠右心室细胞凋亡减少,右心室肥大减轻(均P<0.001),CHOP及GRP78表达水平下调(均P<0.05),Bcl-2表达下降(P=0.020),线粒体中细胞色素C释放减少(P=0.017)。结论慢性缺氧通过诱导心肌细胞内质网应激促进线粒体途径心肌细胞凋亡可能是慢性肺源性心脏病的发病机制之一。

Objective To investigate the role and mechanism of endoplasmic reticulum stress in mitochondrial apoptosis of cardiomyocyte in chronic cor pulmonale rats.Methods Twenty-four rats aged 8 weeks were randomly divided into hypoxia group,intervention group and control group.Model of cor pulmonale was established by atmospheric intermittent hypoxia in hypoxia group and they were fed with normal saline every day by gavage.The rats in intervention group were induced to establish cor pulmonale and administrated with 4-PBA(an inhibitor of endoplasmic reticulum stress)by gavage.The rats in control group were fed in the air and administrated with normal saline by gavage.The rats were killed after the treatment for 21 d and the right ventricle was separated.The slices of right ventricular tissue were produced to determine the apoptosis rate using TUNEL method.Mitochondria from right ventricular tissue was used to detect the mitochondrial membrane potential using JC-1 fluorescent probe.The expression levels of the endoplasmic reticulum stress marker molecules GRP78 and CHOP,apoptosis-related proteins Bcl-2 and cytochrome C were determined by Western blot.Results Compared with control group,the right ventricular hypertrophy was found,the cardiomyocyte apoptosis rate was significantly increased in hypoxia group(all P<0.001),the relative levels of CHOP,GRP78,Bcl-2 and cytochrome C released from mitochondria were significantly increased(P≤0.001).Compared with hypoxia group,the apoptosis and the hypertrophy were also relieved in intervention group(all P<0.001),the expression levels of CHOP,GRP78 were significantly downregulated(all P<0.05),Bcl-2 was decreased(P=0.020),and cytochrome C released from mitochondria was also decreased(P=0.017).Conclusion Chronic hypoxia-induced endoplasmic reticulum stress participates in the pathogenesis of chronic cor pulmonale by inducing cardiomyocyte apoptosis through mitochondrial pathway.