曲美他嗪对心肌梗死后心力衰竭大鼠左心功能和心肌细胞自噬水平的影响

Effects of trimetazidine on left ventricular function and autophagy of cardiomyocytes in rats with heart failure after myocardial infarction

目的探讨曲美他嗪对心肌梗死后心力衰竭大鼠左心功能和心肌细胞自噬水平的影响。方法取24只雄性Wistar大鼠,随机分为假手术组(不结扎左冠状动脉前降支近段)、模型组(结扎左冠状动脉前降支近段制备心肌梗死后心力衰竭大鼠模型)、给药组(心肌梗死后心力衰竭+曲美他嗪每日15 mg/kg),用药4周,三组各8只。通过小动物超声仪测定三组小鼠左心室功能指标,分别采用苏木精-伊红染色和Masson染色观察小鼠心肌组织病理学改变和纤维化情况,根据原位缺口末端标记法(TUNEL法)荧光染色测定小鼠心肌细胞凋亡情况,分别采用免疫印迹法和实时荧光定量聚合酶链反应测定小鼠心肌组织中自噬相关蛋白和基因的表达情况。结果模型组和给药组左心室收缩末期内径(LVESD)和左心室舒张末期末径(LVEDD)较假手术组均明显增厚,左心室射血分数(LVEF)较假手术组均明显降低(P<0.05);给药组LVESD和LVEDD较模型组下降,LVEF较模型组明显升高(P<0.05)。相比假手术组,模型组梗死区心肌细胞水肿和坏死明显,可见诸多炎性细胞浸润,心肌细胞损伤明显,出现明显蓝色胶原沉积,可见大量凋亡小体;相比模型组,给药组心肌组织病理学改变的情况得以明显改善,少见蓝色胶原沉积和凋亡小体。模型组和给药组P62蛋白的表达水平较假手术组均显著上调,LC3B蛋白的表达水平较假手术组均显著下调(P<0.05);给药组P62蛋白的表达水平较模型组显著下调,LC3B蛋白的表达水平较模型组显著上调(P<0.05)。模型组和给药组Atg7 mRNA和Beclin-1 mRNA相对表达量均明显低于假手术组,给药组Atg7 mRNA和Beclin-1 mRNA相对表达量均明显高于模型组(P<0.05)。结论自噬具有保护心肌细胞的功能,应用曲美他嗪给药可提高心肌梗死后心力衰竭大鼠心肌细胞自噬水平,从而减轻心功能障碍,抑制心肌细胞凋亡。

Objective To investigate the effects of trimetazidine on left ventricular function and autophagy of cardiomyocytes in rats with heart failure after myocardial infarction.Methods Twenty-four male Wistar rats were randomly divided into sham operation group(without ligating the proximal left anterior descending artery),model group(ligating the proximal proximal left anterior descending artery to establish the rat model of heart failure after myocardial infarction)and drug-administration group(heart failure after myocardial infarction+trimetazidine 15 mg/kg per day),8 rats in each group.The left ventricular function of the three groups of rats was evaluated by small animal ultrasound.The histopathological changes and fibrosis of myocardium were observed by hematoxylin-eosin staining and Mason staining respectively.The apoptosis of myocardial cells was determined by TUNEL fluorescence staining.The expression of autophagy-related proteins and genes in myocardial tissues were detected by immunoblotting and real-time fluorescence quantitative polymerase chain reaction respectively.Results LVESD and LVEDD in model group and drug-administration group were significantly increased than those in sham-operation group,and LVEF was significantly lower(P<0.05).LVESD and LVEDD in drug-administration group were decreased than those in model group,and LVEF was significantly higher than that in model group(P<0.05).Compared with the sham operation group,the edema and necrosis of myocardial cells in the infarcted area of the model group were obvious,with many inflammatory cells infiltrating,many myocardial cells damaged,obvious blue collagen deposition,and a large number of apoptotic bodies observed.Compared with the model group,the pathological changes of myocardial tissue in the drug-administration group were significantly improved,and blue collagen deposition and apoptotic bodies were rare.The expression level of P62 protein in model group and drug-administration group was significantly higher and the expression level of LC3B protein was significantly lower than those in sham-operation group(P<0.05).The expression level of P62 protein in drug-administration group was significantly lower and the expression level of LC3B protein was significantly higher than those in model group(P<0.05).The relative expression of Atg7 and Beclin-1 in model group and drug-administration group were significantly lower than those in sham operation group,and the relative expression of Atg7 and Beclin-1 in drug-administration group were significantly higher than those in model group(P<0.05).Conclusion Autophagy plays a role in protecting cardiomyocytes.Trimetazidine can improve the autophagy of cardiomyocytes in rats with heart failure after myocardial infarction,thereby alleviating cardiac dysfunction and inhibiting cardiac myocyte apoptosis.