纽兰格林改善线粒体应激抑制心肌梗死后心力衰竭大鼠细胞凋亡

Neuregulin-1 inhibits myocardial cell apoptosis by attenuating mitochondrial stress in rats with heart failure after myocardial infarction

目的观察纽兰格林（NRG）对心肌梗死后心力衰竭大鼠心脏保护作用，并探讨其机制。方法雄性Wister大鼠（体质量200～250g）48只，结扎大鼠前降支建立缺血性心力衰竭模型，4周后存活且建模型成功的28只大鼠被随机分至NRG组和心力衰竭组，分别给予重组人纽兰格林（rhNRG13）10μg·kg^-1·d^-1和等容量注射用水尾静脉注射，10d；另有12只大鼠作为假手术组。超声检查NRG对心力衰竭大鼠心脏功能的影响；透射电镜观察非梗死区心肌组织线粒体超微结构；脱氧核糖核酸缺口末端标记（TUNEL）法测定细胞凋亡指数；免疫荧光法测定线粒体膜电位水平；Caspase-3试剂盒检测caspase-3活性；免疫印迹（Westernblot）法检测细胞浆细胞色素c水平。结果与心力衰竭组大鼠比较，NRG组大鼠左心室收缩末期内径缩小（P〈0．05），左心室射血分数增加（P〈0．01）、短轴缩短率增加（P〈0．05），凋亡指数降低[（11．9±1．4）％与（18．1±3．0）％，P〈0．01）]。线粒体膜电位上升[（249．8±7．4）mV与（222．2±7．5）mV，P〈0．013，细胞色素C释放减少[（0．356±0．024）与（0．664±0．085），P〈0．01]，caspase-3活性减低（P〈0．01）。结论纽兰格林改善心肌梗死后心力衰竭大鼠线粒体应激，抑制心肌细胞凋亡，这一机制可能部分参与了纽兰格林的心脏保护作用。

Objective To study the effect of Neuregulin-1 （NRG） on rat heart failure（HF） after myocardial infarction, and to investigate the underlying mechanism involving in NRG-mediated cardioprotection. Methods 60 adult Wister rats underwent sham operation （n= 12） or coronary ligation （n=48） to induce HF. Four weeks after ligation, 28 animals with HF were randomly divided into NRG group （rats received rhNRG-1 10 μg·kg^-1·d^-1 intravenously for 10 days） or HF group （rats received an equal volume of water intravenously for 10 days）. Left ventricular function was detected by echocardiography. Mitochondrial ultrastructure in non-infarcted myocardium was observed by transmission electronic microscopy. Cell apoptosis was detected by terminal-deoxynucleoitidyl transferase mediated nick end labeling （TUNEL） assay. Mitochondrial membrane potential was measured by immunofluorescence method. Caspase-3 activity was determined by commercial kit. The expression of cytochrome C protein in cytoplasm was detected by Western blot. Results Compared with HF group, the left ventricular end-systolic diameter was decreased, and left ventricular ejection fraction and fractional shortening were increased in NRG group （P〈0.05 or 0.01）. Apoptosis index was reduced in NRG group as compared with HF group （18.1±3.0）G vs. （11.9±1.4）G, P〈 0. 011. Mitochondrial membrane potential was increased and the release of eytochrome c in cytoplasm was reduced in NRG group as compared with HF group （（249.8±7.4） mV vs. （222.2±7.5） mV, （0. 356±0. 024） vs. （0. 664± 0. 085）, both P〈0. 011. Caspase-3 activity was decreased in NRG group as compared with HF group （P〈0.01）. Conclusions NRG attenuats mitochondrial stress and inhibits myocardial cells apoptosis in heart failure rats after myocardial infarction, which may play an important role in the cardioprotection by NRG.