小鼠急性心肌梗死后不同时间点心肌组织自噬水平的动态演变

Dynamic evolution of myocardial autophagy level in AMI mice at different time points

目的研究小鼠急性心肌梗死(AMI)后不同时间点心肌组织自噬水平的动态变化。方法选取8~10周龄SPF级C57BL/6J野生型小鼠40只,随机分为假手术组(Sham组)、AMI组(永久结扎左前降支),每组20只,分别于术后7、14、28 d时,用心脏超声检测心脏功能及结构变化,Masson染色观察小鼠梗死周边心肌组织纤维化,Western blot检测自噬蛋白、透射电镜观察自噬小体、免疫组织化学检查凋亡蛋白表达。结果 Masson染色显示,AMI组梗死周边组织间质纤维化随着时间的推移加重;AMI组7、14和28 d时Bax蛋白较Sham组明显上调(0.71±0.08、0.77±0.05和0.86±0.06 vs 0.53±0.08,P<0.05),Bcl-2和自噬微管相关蛋白轻链3蛋白降低(P<0.05),P62蛋白表达增强(P<0.05);透射电镜示,AMI组梗死周边心肌组织内自噬小体数量明显减少。结论小鼠AMI后梗死周边心肌组织自噬水平进行性降低,心室重构进一步恶化,自噬可能在AMI中起保护作用。

Objective To study the dynamic evolution of myocardial autophagy level in AMI mice at different time points.Methods Forty SPF wild mice aged 8-10 weeks were randomly divided into sham group(n=20) and AMI group(n=20,LAD ligated).Their cardiac function and strcture were detected by cardiac ultrasonography on days 7,14,28 respectively.Masson staining was conducted in the myocardial tissue(MT) surrounding infarction.The fibrosis of autoghagic protein was detected by Western blot, the autophagic bodies were detected by transmission electroscopy and the expression of apoptotic protein was detected with immunohistochemical stainig.Results The fibrosis of infarcted peripheral MT aggregated with the prolonged time in AMI group.The expression levels of Bax were significantly higher, Bcl-2 and LC3 proteins were significantly lower, P62 protein were significantly higher in AMI group than in sham group(P<0.05).Transmission electroscopy displayed that the number of autophagic bodies was significantly smaller in AMI group than in sham group(P<0.05).Conclusion The autophagy level in infarcted peripheral MT decreases progressively, the ventricular structure further aggregates in AMI mice and autophagy level of peripheral MT decreases.Autophagy can protect mice against AMI.