miR-21对缺血/再灌注后血脑屏障保护作用

目的:研究miR-21在脑缺血/再灌注(cerebral ischemia-reperfusion,I/R)损伤过程中对血脑屏障(Blood Brain Barrier)的保护作用。方法:采用线栓法构建SD大鼠脑缺血/再灌注模型。实验随机分为空白质粒组,miR-2l-mimic组和miR-21 inhibitor组。利用Western Blot检测大鼠大脑皮层组织中Bax蛋白的表达变化,透射电镜观察大鼠大脑皮层组织中细胞形态和血脑屏障的完整性,免疫荧光检测大脑皮层组织中自噬相关蛋白LC-3的分布情况。结果:Western Blot实验结果显示:与空白质粒相比,给予miR-2l-mimic的大鼠脑组织中Bax蛋白的表达显著降低,而给予miR-21 inhibitor的大鼠脑组织中Bax蛋白的表达升高;透射电镜结果显示:与空白质粒组相比较,miR-2l-mimic组中内皮细胞周围星形胶质细胞的板层突基本完整,而miR-21 inhibitor组中明显可见自噬小体、溶酶体,并有吞噬物存在;免疫荧光结果显示:与空白质粒组比较,miR-21-mimic组中自噬相关蛋白LC-3表达降低,而miR-21 inhibitor组中LC3蛋白的分布增加。结论:miR-2l可能通过下调Bax蛋白的表达抑制凋亡或通过抑制自噬保护血脑屏障。

Protective Effect of miR-21 on the Blood Brain Barrier after Cerebral Ischemia and Reperfusion

ABSTRACT Objective: To study the protective effect of miR-21 on the blood brain barrier after cerebral ischemia/reperfusion(I/R) injury. Methods: A rat model of cerebral I/R was established by suture method. The rats were randomly divided into the blank plasmid group, miR-2l-mimic group and inhibitor miR-21 group. The expression of Bax protein in the cerebral cortex was detected by Western Blot, the integrity of cell morphology and blood brain barrier was detected by transmission electron microscope, the distribution of autophagy protein LC-3 in the cerebral cortex tissue was detected by immunofluorescence. Results: Western Blot showed that compared with the blank plasmid, the expression of Bax protein in brain tissue of rats in miR-2l-mimic were significantly decreased, but increased expression of Bax protein in the brain tissue s was found in miR-21 in inhibitor-treated rats; electron microscopy results showed that compared with the blank plasmid group, Transmission electron microscopy showed that compared with the blank plasmid groups, miR-2l-mimic groups in the surrounding astrocytes of lamina of endothelial cells process almost complete, Immunofluorescence showed that compared with the blank plasmid group, autophagy related protein LC-3 expression in the miR-21-mimic group was was decreased. Conclusion: MiR-2l could protect the blood brain barrier after cerebral I/R via down-regulating the expression of Bax protein, inhibiting apoptosis and autophagy.