miR-126调控脑缺血大鼠细胞凋亡机制的研究

摘要 目的：探讨脑缺血大鼠microRNA-126（MiR-126）在脑组织和血浆中表达的动态变化及与细胞凋亡的关系。方法：健康雄性SD大鼠45只随机分为3组，其中3只大鼠不作任何处理，用于检测正常大鼠中MiR-126在脑组织和血浆的表达，剩余大鼠随机分为假手术组和模型组，模型组用线栓法造脑缺血大鼠模型。TTC法检测模型组大鼠脑组织梗死病变用以确定造模是否成功；RT-qPCR检测大鼠造模后1、3、6、9、12、24和48小时脑组织和血浆中MiR-126的动态表达变化；采用苏木精-伊红染色法检测脑组织形态学变化；采用Western blot 方法分析相关凋亡蛋白表达的变化。结果：TTC法和H-E染色结果表明，大鼠脑缺血造模成功，模型组大鼠出现脑组织大面积梗死病变；MiR-126和Caspase-3表达在模型组大鼠脑组织和血浆中随着脑缺血时间的延长其表达水平逐渐提高，24 h到达高峰后，在48 h Mi-R126表达强度又降低，但仍然高于假手术组大鼠水平；Caspase-3在正常对照组和假手术组表达量都较少（P>0.05），其他凋亡蛋白Bax和 STAT3相对表达水平趋势同 Caspase-3相似；而Bcl-2表达水平明显降低，趋势与其他凋亡蛋白相反。结论：MiR-126在脑缺血大鼠脑组织和血浆中表达水平明显升高，而且细胞凋亡明显增加，因此MiR-126可能通过促进细胞凋亡对脑缺血大鼠有保护作用，此研究为脑缺血发病机制和诊断提供更多依据。

Expression Changes of microRNA-126 in Brain Tissues and Plasma in Rats with Cerebral Ischemia

ABSTRACT Objective: To investigate the dynamic changes of the expression of microRNA-126 (MiR-126) in brain tissue and plasma in rats with cerebral ischemia and its relationship with apoptosis. Methods: Forty-five healthy male SD rats were randomly divided into 3 groups, of which 3 rats were subjected to no treatment to detect the expression of MiR-126 in brain tissue and plasma in normal rats, and the remaining rats were randomly divided into sham operation groups and models group. The model group was used to create a rat model of cerebral ischemia by the suture method. TTC method was used to detect infarct lesions in the brain tissue of model rats to determine whether the modeling was successful. RT-qPCR was used to detect the dynamic expression of MiR-126 in brain tissue and plasma at 1, 3, 6, 9, 12, 24, and 48 hours after rat modeling. Hematoxylin-eosin staining was used to detect morphological changes of brain tissue. Western blot analysis was used to analyze changes in expression of related apoptotic proteins. Results: (1) The results of TTC and HE staining showed that the cerebral ischemia modeling in rats was successful, and large-area infarct lesions in the brain tissue appeared in the model group rats. (2) Compared with the sham operation group, the expression of MiR-126 in the model group in the brain tissue and plasma became highly, and the expression level gradually increased with the extension of cerebral ischemia time. After reaching the peak at 24 hours, the expression intensity of MiR-126 decreased again at 48 hours, but it was still higher than that of the sham operation rat level. (3) The expression of apoptotic protein of Caspase-3 in normal control group and sham operation group was small, and there was no significant difference between the two groups (P>0.05). While in the model group, the expression level of Caspase-3 increased significantly, and the relative expression level of Caspase-3 gradually increased with the prolongation of cerebral ischemia time, but its expression level decreased again at 48 h, but still higher than that of the sham operation group. The relative expression levels of Bax and STAT3 were similar to those of Caspase-3. The expression trend of apoptotic protein Bcl-2 was obviously opposite to these apoptotic proteins, which meant that the level was significantly reduced. Conclusion: The expression level of miR-126 in brain tissue and plasma of rats with cerebral ischemia was significantly increased, and cell apoptosis was significantly increased. Therefore, MiR-126 may have a protective effect on cerebral ischemia rats by promoting cell apoptosis. This research may provide more evidences for the pathogenesis and diagnosis of cerebral ischemia.