外源性维生素D对小鼠脑缺血/再灌注神经损伤的保护作用

Protective effects of exogenous vitamin D on nerve injury in mice with cerebral ischemia/reperfusion

目的:观察小鼠大脑中动脉闭塞(MCAO)模型制备前5 d连续补充1,25-二羟维生素D3(1,25-VitD3)对缓解小鼠缺血/再灌注(I/R)后脑损伤中的作用。方法:雄性C57BL6小鼠随机分为Sham组、Vehicle组和1,25-Vit D3组,每组10只小鼠;Vehicle组和1,25-VitD3组小鼠均进行大脑MCAO1 h,再灌注24 h后处死小鼠,1,25-VitD3组MCAO手术前5 d连续腹腔注射,100 ng/(kg·d);取各组小鼠脑缺血半影区,进行TTC染色、RT-PCR及免疫组化检测,采用神经功能评分评估小鼠功能缺陷。结果:与sham组相比,Vehicle组小鼠脑梗死体积明显增加,小鼠脑组织中促炎介质IL-6、IL-1β和Gp91phox表达均明显增高(P<0. 05);与Vehicle组相比,补充1,25-VitD3可减少I/R小鼠大约50%梗死体积(P<0. 05),1,25-VitD3组小鼠脑组织中IL-6、IL-1β和Gp91phox表达明显降低(P<0.05),小鼠脑内T调节细胞标志物Foxp3 mRNA表达明显升高(P<0. 05),而转录因子Rorc mRNA表达明显较低(P<0. 05),提示Th17/γδT细胞反应减少,小鼠脑损伤部位中性粒细胞数量明显降低(P<0. 05)。结论:维生素D可以缓解动脉闭塞(MCAO)再灌注脑梗死发展,其机制可能是通过调节小鼠脑I/R中炎症反应。

Objective: To investigate the effects of 1,25-dihydroxyvitamin D3( 1,25-VitD3) supplementation on cerebral injury after ischemia/reperfusion( I/R) in mice with middle cerebral artery occlusion( MCAO). Methods: Male C57 BL6 mice were randomly divided into Sham group,Vehicle group and 1,25-VitD3 group,with 10 mice in each group. Vehicle group and 1,25-VitD3 group were given MCAO for 1 hour,and then killed after reperfusion for 24 hours. Mice in 1,25-VitD3 group were treated with 1,25-Vit D3 at the dose of 100 ng/( kg·d) by injected intraperitoneally for 5 days before MCAO operation. Cerebral ischemic penumbra areas of each group were collected for TTC staining,RT-PCR,TTC staining and immunohistochemistry assay. The function defect of mice was evaluated by using neurological function score. Results: Compared with the sham group,the volume of cerebral infarction in Vehicle group was increased significantly,and the expressions of IL-6,IL-1 beta and Gp91 phox in brain tissues were increased significantly( P<0. 05);compared with Vehicle group,supplementation of 1,25-VitD3 reduced the volume of cerebral infarction by about 50% in I/R mice( P<0. 05),and the expressions of IL-6,IL-1 beta and Gp91 phox in brain tissues of 1,25-VitD3 group were decreased significantly( P<0. 05). The expression of Foxp3,a T-regulatory cell marker,was significantly increased in the brain of mice( P<0. 05),while the expression of Rorc,a transcription factor,was significantly decreased( P<0. 05),suggesting that Th17/gamma Delta T-cell response was reduced and the number of neutrophils in the brain injury site of mice was significantly reduced( P<0. 05). Conclusion:Vitamin D could alleviate the development of cerebral infarction after arterial occlusion( MCAO) reperfusion,and its mechanism may be through regulating the inflammatory response in mouse brain I/R.