黄芪甲苷保护大鼠缺血/再灌注心脏的内质网应激机制研究

Role of ERS in Astragaloside Ⅳ-induced cardioprotection against ischemia / reperfusion injury in rats

目的研究黄芪甲苷保护缺血/再灌注心脏的内质网应激(ERS)机制。方法建立离体心脏缺血/再灌注模型,♂Wistar大鼠结扎冠状动脉进行心肌缺血30 min/再灌注120 min,随机分成假手术组、缺血/再灌注组、ERS抑制剂牛磺熊脱氧胆酸(TUDCA)组、黄芪甲苷组;Western blot检测缺血期及再灌注期ERS分子伴侣葡萄糖调节蛋白78(GRP78)的表达;激光扫描共聚焦显微镜免疫荧光化学染色法检测GRP78的表达;TTC法测定心肌梗死面积;HE染色观察心肌组织形态学改变。结果与假手术组相比,缺血期GRP78表达没有明显增加,再灌注期GRP78表达明显增加,黄芪甲苷能够模拟TUDCA明显抑制再灌注期GRP78的表达、减少心肌梗死面积、改善心肌组织的形态,差异具有统计学意义(P<0.05)。结论 ERS发生于再灌注期而不是缺血期,黄芪甲苷通过抑制ERS保护大鼠缺血/再灌注心脏。

Aim To explore the role of endoplasmic reticulum stress（ ERS） in Astragaloside Ⅳ-induced cardioprotection against ischemia / reperfusion injury in rats. Methods A model of myocardial ischemia 30 min followed by 120 min reperfusion was made by ligating coronary artery in male Wistar rats. Rats were divided randomly into 4 groups： sham group,ischemia /reperfusion group,ERS inhibitor TUDCA group,Astragaloside Ⅳ group. Myocardial samples were collected from the risk zones during ischemia and reperfusion,ERS was determined by measuring levels of glucose regulated protein 78（ GRP78）,an established marker of ERS with Western blot. Immunofluorescence study was used to test GRP78 intensity with laser scanning confocal microscopy,TTC method was used to measure the infarct size,hematoxylin-eosin staining was used to observe the changes of morphological changes of myocardium. Results There was no statistical difference in GRP78 expression during ischemia compared to the sham group,but was markedly increased upon reperfusion. Astragaloside Ⅳ could mimic TUDCA and significantly decreased the GRP78 expression,reduced infarct size and improved the morphology of myocardial tissue with a significant statistical difference compared with the control group（ P 0. 05）. Conclusions ERS is induced upon reperfusion but not during ischemia in isolated rat hearts. Astragaloside Ⅳ prevents myocardial reperfusion injury presumably by the inhibition of ERS.