miR-122对脑缺血再灌注损伤小鼠脑梗死体积及胰岛素样生长因子-1受体通路的影响

目的：探讨miR-122 对脑缺血再灌注损伤小鼠脑梗死体积及胰岛素样生长因子-1 受体（IGF-1R）通路的影响。方法：将SPF 级雄性 C57BL 小鼠，运用线栓法建立脑缺血再灌注损伤（I/R）模型，分对照组（ 假手术组）、模型组（I/R 模型组）、模拟物组（I/R 模型+miR-122 模拟物）、抑制物组（I/R 模型+miR-122 抑制物），比较小鼠神经功能和认知功能，测定小鼠脑梗死体积，H-E 染色检测脑组织结构改变，RT-PCR 测定miR-122、IGF-1R mRNA水平，免疫印迹测定IGF-1R 蛋白表达，流式细胞术检测神经元细胞凋亡情况。结果：与对照组相比，模型组和模拟物组小鼠旋转圈数明显增多，悬挂实验评分降低，且模拟物组小鼠旋转圈数多于模型组，悬挂实验评分低于模型组；与模型组相比，抑制物组小鼠旋转圈数明显减少，悬挂实验评分明显升高。与对照组相比，模型组和模拟物组小鼠PT%、T% 值均降低，且模拟物组较模型组降低的更为显著；与模型组相比，抑制物组小鼠PT%、T% 值显著升高。与对照组相比，模型组和模拟物组大鼠脑梗死体积明显增加，且模拟物脑梗死体积大于模型组；与模型组相比，抑制剂组大鼠脑梗死体积显著减小。对照组脑组织结构完整，神经元排列紧密，无染色不匀现象，模型组脑组织神经元排列呈疏松状态，着色不匀，有大量空泡样病理结构改变，模拟物组脑组织结构改变较模型组严重，抑制物组脑组织损伤病理变化逐渐减弱，神经元排列较密，空泡样病理改变减少。与对照组对比，模型组miR-122 水平呈显著升高状态，其余3 组miR-122 水平从高到低依次为模拟物组、模型组、抑制物组。与对照组比较，模型组、模拟物组IGF-1R mRNA 水平均呈下降趋势；与模型组比较，模拟物组 IGF-1R mRNA水平有所升高。与对照组比较，模型组IGF-1R 蛋白表达明显下降，模型组IGF-1R 蛋白高于模拟物组，抑制物组IGF-1R 蛋白高于模型组、模拟物组。神经元细胞凋亡从高到低依次为模拟物组、模型组、抑制物组、对照组，4组神经元细胞凋亡率比较差异有统计学意义。结论：miR-122 低表达可减少脑缺血再灌注损伤小鼠脑梗死体积，增加IGF-1R 通路活性，对脑缺血再灌注损伤小鼠脑组织有一定的预防作用。

Effect of miR-122 on cerebral infarction volume and insulin like growth factor-1 receptor pathway in mice with cerebral ischemia-reperfusion injury

Objective To investigate the effect of miR-122 on cerebral infarction volume and insulin like growthfactor-1 receptor（ IGF-1R） pathway in mice with cerebral ischemia-reperfusion injury. Methods SPF grade maleC57BL mice were selected to establish a mouse model of cerebral ischemia-reperfusion injury（ I/R）by threadthrombosis. The rats were divided into sham group（ normal mice）， model group， analog group（ I/R model + miR-122 mimic）， and inhibitor group（ I/R model+miR-122 inhibitor）. The volume of cerebral infarction in mice wasmeasured and brain tissue structure changes were observed by H-E staining. miR-122， IGF-1R mRNA levels weremeasured by RT-PCR. IGF-1R protein was detected by Western blotting， and neuronal apoptosis was detected byflow cytometry. Results Compared with the sham group， the number of rotations in model group and analog groupincreased significantly， and the score of suspension experiment decreased， and the number of rotations in analoggroup was higher than that in model group， and the score of suspension experiment in analog group was lower thanthat in model group. Compared with model group， the rotation number of mice in inhibitor group was significantlydecreased， and the suspension test score was significantly increased. Compared with the sham group， PT% and T%values in model group and analog group were decreased， and the decrease in analog group was more significant thanthat in model group. Compared with model group， PT%and T% of mice in inhibitor group were significantlyincreased.Compared with the sham group， the infarctvolume in the model group increased significantly. Compared with the model group， the volume of cerebral infarctionin the analog group increased. Compared with the analog group， the infarct volume of the inhibitor group wassignificantly reduced. In the sham group， the brain tissue was intact， the neurons were closely arranged， and therewas no uneven staining. Neurons in the model group were loosely arranged， unevenly colored， and there were a largenumber of vacuole-like pathological changes. The structural changes of the brain tissue in the analog group weremore serious than those in the model group， and the pathological changes of the brain tissue in the inhibitor groupgradually weakened， the neurons were densely arranged， and the vacuole-like pathological changes were reduced.Compared with the sham group， the miR-122 level in the model group was significantly elevated. The miR-122 levelsof the remaining three groups from high to low were analog group， model group， inhibitor group. Compared withsham group， IGF-1R mRNA level in both model group and analog group showed a downward trend. Compared withthe model group， the levels of IGF-1R mRNA in the analog group was increased. Compared with the sham group，the expression of IGF-1R mRNA protein in the model group significantly decreased. The expression of IGF-1Rprotein in model group was higher than that in analog group. The difference of IGF-1R protein expression between thefour groups was significant. Conclusion The low expression of miR-122 can protect mice from cerebral ischemiareperfusioninjury， reduce the volume of cerebral infarction and improve the activity of IGF-1R pathway