Objective:To observe the expression and anti-apoptosis of microRNA-21 (miR-21) in rat myocardium during early ischemia-reperfusion injury (I/R).Methods:Sprague-Dawley rats were randomly divided into 5 groups:a control group (transfected with rAAV9-ZsGreen by coronary injection),a miR-21group (transfected rAAV9-ZsGreen-pre-miR-21 by coronary injection),a sham group (open-chest only),an I/R group (I/R),and an I/R+miR-21 (I/R after transfected rAAV9-ZsGreen-pre-miR-21 by coronary injection).Realtime PCR was used to assess the expression level of miR-21.Immunohistochemistry and Western blot were used to determine the expression of Bcl-2,Bax,caspase-3 and Bcl-2/Bax.Results:MiR-21 was increased by 4.43 times in the miR-21 group (P＜0.001).MiR-21 was down-regulated in the ischemia zone after I/R compared with the sham group (P＜0.05),but that in the non-ischemia zone was significantly increased compared with the sham group (P＜0.01).MiR-21 expression was decreased in the I/R group compared with that in the sham group at 1 h,2 h and 6 h after I/R (P＜0.05),and it was up-regulated in the I/R+miR-21 group at the same time point compared with the I/R group (P＜0.01).The expression of Bcl-2,Bax,and caspase-3 was up-regulated and Bcl-2/Bax was decreased in the ischemia zone in the I/R group and I/R+miR-21 group than the sham group(P＜0.05).Compared with the I/R group,the expression of Bcl-2 and caspase-3 was down-regulated and Bcl-2/Bax was increased in the ischemia zone in the I/R+miR-21 group (P＜0.05).Conclusion:MiR-21 expression is down-regulated and cell apoptosis is increased in rat myocardium during early ischemia-reperfusion injury.Myocardial cell apoptosis may be alleviated by miR-21 over-expression.%目的:观察microRNA-21(miR-21)在缺血再灌注损伤(I/R)早期大鼠心肌的表达及对细胞凋亡的影响.方法:SD大鼠随机分为对照组(冠状动脉注射转染空白对照病毒rAAV9-ZsGreen),miR-21组(冠状动脉注射转染rAAV9-ZsGreen-pre-miR-21),Sham组(仅开胸挂线),I/R组(进行I/R处理),I/R+miR-21(转染rAAV9-ZsGreen-pre-miR-21后再进行I/R处理).用Realtime-PCR检测大鼠miR-21水平,免疫组织化学及Western印迹方法检测Bd-2,Bax,caspase-3水平并计算Bcl-2/Bax比值.结果:冠状动脉注射rAAV9-ZsGreen-pre-miR-21可使miR-21表达增加4.43倍(P＜0.001);与Sham组比较,I/R组大鼠缺血区miR-21水平下调(P＜0.05),而非缺血区miR-21升高(P＜0.05);与Sham组比较,I/R组再灌注1,2,6hmiR-21水平进行性下降(P＜0.05),在同一时间点I/R+miR-21组较I/R组miR-21表达升高(P＜0.05);与Sham组比较,再灌注6h时I/R及I/R+miR-21组Bcl-2增高、caspase-3增高、Bcl-2/Bax降低(P＜0.05),与I/R组比较,I/R+miR-21组Bcl-2下调、caspase-3下调、Bcl-2/Bax增高(P＜0.05).结论:I/R早期大鼠心肌缺血区miR-21表达下降,细胞凋亡增加,过表达miR-21可改善细胞凋亡.
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