Urocortin抑制心肌缺血再灌注诱导的自噬

Urocortin inhibits myocardium ischemia/reperfusion-induced autophagy

目的研究urocortin(UCN)对缺血再灌注诱导的心肌细胞自噬的影响,探讨UCN的心肌保护机制。方法构建大鼠在体心脏缺血再灌注损伤和离体新生大鼠心肌细胞的缺氧复氧模型,进行缺血/缺氧1h再灌注/复氧2h的损伤,在缺血/缺氧前1h给予UCN预处理;在再灌注/复氧2h后观察UCN对缺血再灌注/缺氧复氧诱导的心肌损伤、细胞自噬和自噬相关基因表达的影响。结果 UCN预处理可以显著降低缺血再灌注损伤导致的心肌损害,使梗死面积降低,血清肌酸激酶(CK)、乳酸脱氢酶(LDH)降低;增加缺氧复氧离体心肌细胞活力、减少培养上清的LDH水平。与上述心肌保护作用相伴随的是UCN预处理还能抑制缺氧复氧导致的心肌细胞自噬,使LC3BⅡ/LC3BⅠ的比值显著降低,并且抑制自噬相关基因Beclin1、Bnip3的mRNA表达。结论 UCN可以抑制缺血再灌注诱导的心肌细胞自噬,可能在抗缺血再灌注损伤中起重要作用。

Objective To study the regulatory effect of urocortin （UCN） on ischemia/reperfusion （I/R）-induced myocardial autophagy, so as to explore the myocardial protection mechanism of UCN. Methods Cardiac I/R model was established with rats and hypoxia/reoxygenation（H/R） model was also established with neonatal rat cardiomyocytes. The injury was created by ischemic/hypoxia for 1 h plus reperfusion/reoxygenation for 2 h, and UCN pretreatment was given 1 h before ischemia/hypoxia. The I/R or H/R-induced myocardial injury, myocardial autophagy and autophagy-related gene expression were observed 2 h after reperfusion/reoxygenation. Results UCN pretreatment greatly reduced I/R-induced myocardial damage by decreasing the infarct size, serum creatine kinase （CK） and lactate dehydrogenase （LDH） concentration, increasing the vitality of H/R cardiomyocytes in vitro, and reducing LDH level in the culture supernatant. Moreover, UCN pretreatment also inhibited H/R-induced myocardial autophagy by reducing the ratio of LC3B Ⅱ/LC3B I and inhibiting expression of autophagyrelated genes （Beclinl and Bnip3）. Conclusion UCN can inhibit I/R-induced myocardial autophagy, which may play an important role in the protection against I/R injury,