虫草素预处理减轻SD大鼠心肌缺血再灌注损伤

目的:研究大鼠心肌缺血再灌注(IR)损伤中,虫草素(cordycepin,Cordy)能否通过调节微小RNA-455(miR-455)的表达和减少内质网应激(endoplasmic reticulum stress,ERS)引起的凋亡发挥心肌保护作用。方法:体重250~300 g的SD大鼠随机分为3组:对照(control)组,大鼠只进行开胸手术;IR组,大鼠心肌缺血30 min,再灌注120 min;虫草素治疗组(IR+Cordy组):大鼠缺血再灌注前给予虫草素(10 mg/kg)股静脉注射,每天1次,共注射1周。全自动化学分析法检测大鼠血清中乳酸脱氢酶(LDH)和肌酸激酶同工酶MB(CK-MB)活性。TUNEL试剂盒检测心肌内皮细胞(endothelial cells,EC)凋亡率,电镜观察EC超微结构的改变。RT-q PCR法检测心肌组织miR-455及ERS介导的细胞凋亡信号通路的标志物葡萄糖调节蛋白78(glucose-regulated protein 78,Grp78)和caspase-12的mRNA表达。结果:与control组比较,IR组EC的凋亡率明显升高(P0.05);与IR组比较,虫草素组EC的凋亡率明显下降(P0.05)。与control组比较,IR组的EC线粒体肿胀,膜不规整,内皱疏松有空泡,基粒消失,核膜不规整,染色质浓集、边集,核仁消失,甚至出现凋亡小体;IR+Cordy组与IR组比较症状大为改善。与control组比较,IR组心肌组织Grp78和caspase-12的mRNA及miR-455含量均升高(P0.05);与IR组比较,IR+Cordy组Grp78和caspase-12的mRNA及miR-455的含量均降低(P0.05)。结论:虫草素可有效减轻心肌IR后大鼠心肌EC凋亡,降低心肌组织miR-455表达,抑制内质网应激。

Preconditioning with cordycepin attenuates myocardial ischemia-reperfusion injury in SD rats

AIM: To study whether cordycepin (Cordy) plays a role in myocardial protection by regulating the expression of microRNA-455 (miR-455) and reducing apoptosis induced by endoplasmic reticulum stress in the ischemia-reperfusion (IR) rats. METHODS: SD rats (250~300 g) were randomly divided into 3 groups:control group, the chests of the rats were only opened; IR group, the rats were given myocardial ischemia for 30 min, and then reperfusion for 120 min; IR+Cordy group:before IR, the rats were given Cordy (10 mg/kg) through femoral vein injection once a day for one week, and the last injection was given 30 min before ischemia. Automated biochemical analysis was used to detect rat serum activity of LDH and CK-MB. The myocardial endothelial cell (EC) apoptotic rate was measured by TUNEL, and the ultrastructural changes of the myocardial EC were observed under transmission electron microscope. RT-qPCR was used to detect the expression of miR-455 and the mRNA levels of glucose-regulated protein 78 (Grp78) and caspase-12 in the myocardium. RESULTS: Compared with control group, EC apoptosis in IR group was significantly increased (P<0.05). Compared with IR group, EC apoptosis in IR+Cordy group decreased significantly (P<0.05). Compared with control group, swelling of mitochondria, irregular membrane, loose wrinkles with vacuoles, disappeared matrix granules, irregular nuclear membrane, chromatin condensation, disappeared nucleoli and even small apoptosis body in the EC were found in IR group. Compared with IR group, the symptoms in IR+Cordy group were greatly improved. Compared with control group, the mRNA expression of Grp78 and caspase-12 as well as the miR-455 level in IR group was increased (P<0.05). Compared with IR group, the mRNA expression of Grp78 and caspase-12, as well as the miR-455 level in IR+Cordy group was decreased (P<0.05). CONCLUSION: Cordycepin attenuates myocardial EC apoptosis, down-regulates the expression of miR-455, and inhibits endoplasmic reticulum stress in the myocardium.