siRNA沉默MAG促进脑出血后大鼠运动功能的改善

Therapeutic effect of MAG gene silencing by siRNA on remyelination and motor recovery after intracerebral hemorrhage in rats

目的:研究慢病毒介导的siRNA沉默髓鞘相关糖蛋白(MAG)对脑出血后脱髓鞘再生和神经功能恢复的影响。方法:SD大鼠45只,随机分为3组:模型+siRNA组、模型+PBS组和正常对照组,每组15只。胶原酶诱导建立脑出血模型,据不同组别于模型术后1 d立体定向下进行侧脑室注射携带MAG基因siRNA的慢病毒和PBS。分别于治疗前1 d和治疗后1、7、14、21 d用Rotarod运功功能评分检测大鼠神经功能情况,应用劳克坚牢蓝(luxol fast blue)检测脑损伤区的神经纤维恢复情况,利用免疫组化和Western blotting检测MAG的表达变化。结果:Rotarod评分检测脑出血模型大鼠术后的运动功能,模型+siRNA组的神经功能改善和神经纤维修复较模型+PBS组明显提高(P<0.05),劳克坚牢蓝染色示siRNA组较PBS组的神经纤维损害范围缩小,siRNA组的MAG蛋白的表达较PBS组明显下降(P<0.05)。结论:siRNA沉默MAG后明显提高神经纤维髓鞘再生能力,促进脑出血后神经功能缺失的修复。

AIM ： To study the functional rehabilitative effects of lentiviral vector-mediated siRNA silencing myelin-associated glycoprotein （MAG） on neurological improvement and remyelination after intracerebral hemorrhage （ICH） in rats. METHODS： ICH was induced in 45 adult male Sprague-Dawley rats by a stereotactically guided injection of bacterial type IV collagenase into the right internal capsule. Lentiviral vector-mediated siRNA targeting MAG （siRNA）, or PBS was administered left intracerebroventricularly 1 d after right internal capsule ICH. The Rotarod motor test scores were determined 1 d before and 1 d, 7 d, 14 d and 21 d after treatment. Luxol fast blue staining, immunohistological stai- ning and Western blotting were used to detect the changes of MAG. RESULTS ： Compared with PBS group, the changes of Rotarod motor test scores indicated that the ICH rats receiving siRNA had significant functional recoveries. As indicated by Luxol fast blue staining, the area of demyelination in percentage was obviously reduced in siRNA treatment group as com- pared with PBS group after ICH （P 〈 0.05）. The expression of MAG detected by immunohistological staining and Western blotting was significantly lower in siRNA-treated brain than that in PBS group （P 〈 0.05）. CONCLUSION ： siRNA targe- ting MAG contributes to the remarkable functional recovery after ICH. The treatment promotes nerve fiber remyelination by down-regulation of the MAG expression after ICH in rats.