微小RNA-181b通过调节热休克蛋白A5在缺血性脑卒中小鼠中的作用

目的 探讨微小RNA-181b（miR-181b）在缺血性脑卒中小鼠脑损伤中的作用及机制。 方法 采用小鼠大脑中动脉阻塞(MCAO)模型模拟缺血性脑损伤；Real-time PCR检测miR-181b mRNA表达情况；蛋白印迹观察miR-181b靶蛋白热休克蛋白A5 (HSP A5)蛋白水平变化情况；Nissl方法检测皮层缺血神经元的缺失情况；行为学方法评估小鼠的神经行为学功能损伤程度。 结果 侧脑室注射miR-181b拮抗剂可使脑内miR-181b表达水平明显降低(P<0.05，n=3)；MCAO后小鼠的神经行为学功能受到严重损伤，miR-181b拮抗剂可明显缓解这些行为学改变(P<0.05，n=6)；下调miR-181b可以提高HSPA5蛋白水平(P<0.05, n=3)； MCAO后小鼠皮层有一定程度的神经细胞缺失，预先给予miR-181b拮抗剂发挥保护作用，神经细胞缺失减少(P<0.05，n=3)。 结论 miR-181b可能通过调节HSPA5蛋白的表达在缺血性脑卒中小鼠脑损伤中发挥重要作用。

Effect of microRNA-181b on ischemic stroke by regulating the heat shock protein A5 in mice

Objective To explore the role of microRNA-181b (miR-181b) in cerebral ischemic injury in vivoand its mechanism. Methods Using middle cerebral artery occlusion (MCAO) model to mimic ischemic injury in vivo, the heat shock protein A5(HSPA5)protein level was determined by using Western blotting. The extent of neural cell loss in ischemic cortex after MCAO was assessed by Nissl staining. Neurological score was performed to evaluate the degree of cerebral ischemic injury after MCAO. Results We found that miR-181b antagomir down-regulated miR-181b expression levels in cerebral ischemic cortex of mice after MCAO(P<0.05,n=3). MiR-181b antagomir improved neurological deficit of mice at 24 hours after transient MCAO (P<0.05,n=6). HSPA5 protein levels were significantly up-regulated in ischemic cortex of mice after MCAO，and miR-181b antagomir further up-regulated HSPA5(P<0.05,n=3).Consequently, miR-181b antagonists attenuated neural cell loss in ischemic cortex after MCAO(P<0.05,n=3). Conclusion MiR-181b plays an important role in ischemic injury of mice through regulating HSPA5 protein level.