Ghrelin及其受体在大鼠心肌梗死后的动态表达

Expression of Ghrelin and its receptor in rats after coronary artery ligation

目的 Ghrelin是近年发现的一种新的生长激素释放肽,具有心血管保护效应。本研究旨在观察心肌梗死(MI)后Ghrelin及其受体GHSR-1a的动态表达及其变化。方法 30只SD雄性大鼠,随机分为四组,分别为假手术组(6只),心肌梗死后3 d组(8只),梗死7 d组(8只),梗死28 d组(8只)。采用冠状动脉结扎法制作心肌梗死模型,假手术组只在冠状动脉下穿线,但不结扎。采用实时定量PCR方法检测梗死边缘心肌Ghrelin及GHSR-1a mRNA表达,免疫印迹法检测梗死边缘心肌Ghrelin及GHSR-1a蛋白表达及分布。结果与假手术组比较,MI后3 d、7 d、28 d梗死周边区域心肌中Ghrelin mRNA表达明显降低(P<0.05),且呈逐渐下降趋势;而GHSR-1a mRNA表达显著增加(P<0.05);梗死3 d组与梗死7 d组差异无统计学意义(P>0.05)。免疫印迹显示假手术组大鼠心肌显示出了较强的Ghrelin阳性表达,而心肌梗死后Ghrelin阳性表达明显降低(P<0.05);与此相反,GHSR-1a蛋白表达在梗死后明显增加(P<0.05)。结论 Ghrelin/GHSR-1a系统在梗死后心脏重构中可能起着重要作用,并可作为防止心脏重构的一个新的干预靶点。

Objective Ghrelin is a novel growth hormone-releasing peptide, which has been shown to exert beneficial effects on cardiac function and ventricular remodeling. The present study aimed to investigate the expression of ghrelin and the growth hormone （GH） secretagogue receptor 1a （GHSR-1a）. Methods After ligation of the anterior descending artery （LAD）, adult male Sprague-Dawley rats were randomized to 3 d, 7 d and 28 d groups, with eight rats in each group. Another six rats underwent thoracotomy and pericardiotomy, but not LAD ligation （Sham group）. Expressions of both ghrelin and GHSR-1 a were assessed by means of imrnunohistochemistry and real-time PCR. Results Cardiac expression of ghrelin increased on day 3, 7 and 28 compared with the sham group （P〈0.05）. In contrast, the GHSR-1a mRNA levels increased during the same days （P〈0.05）. Decreased expression of ghrelin and increased expression of GHSR-1a were also observed in infarcted heart. Conclusion The ghrelin/GHSR-1a system may play an important role in regulating cardiac remodeling after MI and provide a potential pharmacological target for treating cardiac remodeling.