脑特异性miRNA-9介导IGF-1R信号对脑缺血再灌注神经损伤大鼠的保护及作用机制

Protection and mechanism of brain-specific miRNA-9 regulating IGF-1R signaling on cerebral ischemia-reperfusion injury in rats

目的:探究脑特异性miRNA-9介导IGF-1R信号对脑缺血再灌注神经损伤(CI/RI)大鼠的保护及作用机制。方法:将40只大鼠随机分为对照组(sham组)、CI/RI组、miR-NC组和miR-9 inhibitor组,每组各10只。通过神经行为学评分检测神经功能,TTC染色检测脑梗死面积,HE染色检测脑组织病理学变化,TUNEL检测神经元凋亡,蛋白质印迹法检测脑组织中miR-9、IGF-1R和IGF-1表达。比较不同组别的神经行为学评分、脑梗死面积、脑组织病理学变化、神经元凋亡情况、脑组织中miR-9、IGF-1R和IGF-1的表达水平。结果:和sham组相比,CI/RI组神经功能评分、海马组织中miR-9相对表达量、脑梗死面积、神经元凋亡数量均升高(P<0.05);和CI/RI组相比,miR-9 inhibitor组神经功能评分、海马组织中miR-9相对表达量、脑梗死面积、神经元凋亡数量均降低(P<0.05)。miR-NC组和CI/RI组神经功能评分、海马组织中miR-9相对表达量、脑梗死面积、神经元凋亡数量比较,差异无统计学意义(P>0.05)。和sham组相比,CI/RI组、miR-NC组和miR-9 inhibitor组大鼠脑组织中IGF-1、IFG-1R蛋白表达升高(P<0.05);miR-9 inhibitor组大鼠脑组织中IGF-1、IFG-1R蛋白表达高于CI/RI组(P<0.05);和miR-NC组相比,miR-9组染野生型荧光素酶活性增加(P<0.05)。结论:抑制miR-9可对CI/RI大鼠脑组织产生保护作用,其作用机制与促进IGF-1R信号通路相关。

Objective:To explore the the protective effect and mechanism of brain-specific miRNA-9 regulating IGF-1R signaling on cerebral ischemia-reperfusion injury in rats.Methods:40 rats were divided into sham group,CI/RI group,miR-NC group and miR-9 inhibitor group,with 10 rats in each group.Neurobehavioral score was used to detect neurological function,cerebral infarction area was detected by TTC staining,the pathological changes of brain tissue was detected by HE staining,neuronal apoptosis were detcted by TUNEL,the expression of miR-9,IGF-1R and IGF-1 in brain tissue were detected by Western blotting.The neurobehavioral score,cerebral infarction area,pathological changes of brain tissue,neuronal apoptosis and the expression levels of miR-9,IGF-1R and IGF-1 in brain tissue were compared among different groups.Results:Compared with the sham group,the neurological function scores,relative expression of miR-9 in the hippocampus,cerebral infarction area,and the number of neurons apoptotic were significantly increased in the CI/RI group(P<0.05),compared with the CI/RI group,the neurological function score,the relative expression of miR-9 in the hippocampus,area of cerebral infarction,and the number of neurons apoptotic were significantly decreased in the miR-9 inhibitor group(P<0.05).There were no significant differences in neurological function score,relative expression of miR-9 in hippocampus,cerebral infarction area,and the number of neuronal apoptosis between the miR-NC group and the CI/RI group(P<0.05).Compared with the sham group,the protein expressions of IGF-1 and IFG-1R in the brain tissue of the CI/RI group,miR-NC group and miR-9 inhibitor group were significantly increased(P<0.05).The protein expressions of IGF-1 and IFG-1R in mouse brain tissue in miR-9 inhibitor group were significantly higher than those in CI/RI group(P<0.05).Compared with the miR-NC group,the wild-type luciferase activity in the miR-9 group was significantly increased(P<0.05).Conclusion:Inhibition of miR-9 can protect the brain tissue of rats with cerebral ischemia-reperfusion injury,and its mechanism is related to the promotion of IGF-1R signaling pathway.