二甲双胍对大鼠脊髓损伤后内质网应激和细胞凋亡的影响

摘要

Objective:To detect the effects of metformin(MET)on ER stress and apoptosis after spinal cord injury(SCI)in rats.Methods:Adult female SD rats were randomly divided into three groups:sham group(Sham group),spinal cord injury group(SCI group)and MET intervention group(50g/kg/day).SCI rat model was established at T10 section by Allen's weight drop method.Spinal cord tissues were harvested 7 days after spinal cord injury.Real-time quantitative PCR was used to detect the expressions of GRP78,CHOP,and caspase-12 mRNA.The expression of GRP78,CHOP,caspase-12,and active caspase-3 was detected by Western blotting and immunofluorescence labeling technique.The fluorescent TUNEL staining was used to detect apoptosis.The BBB score was used to detect the recovery of hindlimb motor function in rats.Results:Compared with sham group,the mRNA and protein levels of GRP78,CHOP,and caspase-12 were significantly increased and so were the protein levels of active caspase-3 and the number of apoptosic cells,while the BBB scores were decreased significantly in SCI group.Compared with SCI group,the mRNA and protein levels GRP78,CHOP,and caspase-12,and the protein levels of active caspase-3 were significantly reduced,and the apoptosis had the same trend;however,BBB scores were increased significantly in MET group.Conclusion:Metformin may inhibit the apoptosis,and promote the recovery of hindlimb motor function by inhibiting endoplasmic reticulum stress after spinal cord injury in rats.%目的:研究二甲双胍(MET)对大鼠脊髓损伤(SCI)后内质网应激(ERS)和细胞凋亡的影响,探讨二甲双胍对SCI的保护作用及机制.方法:成年雌性SD大鼠随机分为3组,分别是假手术组(Sham组)、单纯脊髓损伤组(SCI组)和二甲双胍干预组(MET组).采用Allen方法制备大鼠SCI模型,MET组和SCI组大鼠建模后,立即腹腔注射MET(50mg·kg-1·d-1)或等量生理盐水,连续处理7天后,取脊髓组织,用实时定量PCR检测各组脊髓组织中葡萄糖调节蛋白78(GRP78),CCAAT/增强子结合蛋白同源蛋白(CHOP)和半胱氨酸的天冬氨酸蛋白水解酶-12(caspase-12)的mRNA水平,免疫印迹检测各组脊髓组织中GRP78、CHOP、caspase-12和active caspase-3的蛋白水平,免疫荧光染色检测各组脊髓组织中GRP78、CHOP 和caspase-12的蛋白水平,TUNEL染色法检测各组脊髓组织中细胞凋亡水平,BBB评分检测大鼠SCI后运动功能情况.结果:与Sham组相比,SCI组中GRP78、CHOP和caspase-12的mRNA和蛋白水平明显升高,active caspase-3蛋白表达和细胞凋亡数目明显增加,BBB评分明显降低;与SCI组相比,MET组中GRP78、CHOP和caspase-12的mRNA和蛋白水平明显降低,active caspase-3蛋白表达和细胞凋亡数目明显减少,BBB运动评分明显升高.结论:二甲双胍可以抑制大鼠SCI后细胞凋亡,促进后肢运动功能恢复,其机制可能与抑制ERS有关.