右美托咪定对蛛网膜下腔出血大鼠早期脑损伤的影响及机制

Dexmedetomidine reduces early brain damage caused by subarachnoid hemorrhage through inflammatory pathway

目的探讨右美托咪定(Dex)对蛛网膜下腔出血(SAH)大鼠早期脑损伤的影响,并探讨其作用机制。方法将SD大鼠分为假手术组、SAH组和SAH+Dex组,SAH组和SAH+Dex组采用颈内动脉刺破法建立SAH模型,假手术组仅进行手术操作但不穿孔。术后2 h,SAH+Dex组腹腔注射25 g/kg Dex,SAH组腹腔注射等体积生理盐水,假手术组不进行药物干预。术后24 h,对存活大鼠进行神经功能评分;处死大鼠,测算脑水分含量;暴露脑组织基底池,进行SAH分级评分;取脑组织,采用免疫荧光双标法检测小神经胶质细胞及其亚型含量,ELISA法检测炎症因子IL-4、IL-13、IL-1、IL-6、TNF-α含量,Western blotting法检测血脑屏障相关蛋白Occludin、ZO-1及凋亡相关蛋白caspase-3、Bax、Bcl-2表达。结果与假手术组比较,SAH组神经功能评分降低,脑水分含量和SAH分级评分增加;脑组织小神经胶质细胞数和M1型含量增加;脑组织IL-13含量降低,IL-1、IL-6、TNF-α含量升高;脑组织Occludin、ZO-1、Bcl-2蛋白表达降低,caspase-3、Bax蛋白表达及Bax/Bcl-2比值升高(P均<0.05)。与SAH组比较,SAH+Dex组神经功能评分增加,脑水分含量降低;脑组织小神经胶质细胞数和M1型含量降低,M2型含量增加;脑组织IL-4、IL-13水平升高,IL-1、IL-6、TNF-α水平降低;脑组织Occludin、ZO-1和Bcl-2蛋白表达增加,caspase-3、Bax蛋白表达及Bax/Bcl-2降低(P均<0.05)。结论Dex对SAH后大鼠具有神经保护作用,其机制可能与修复血脑屏障、调整小神经胶质细胞的亚型、抑制促炎因子的释放、降低细胞凋亡有关。

Objective To investigate the effect of dexmedetomidine(Dex)on the early brain injury of rats caused by subarachnoid hemorrhage(SAH)and to explore its mechanism.Methods SD rats were divided into 3 groups:sham group,SAH group,and SAH+Dex group.The SAH models were established by internal carotid artery puncture in the SAH group and the SAH+Dex group.The rats in the sham group underwent a similar surgical procedure but were not perforated.The rats in the SAH+Dex group were given 25μg/kg Dex intraperitoneally at 2 h after surgery.At 24 h after operation,the mortality,neurological function score,SAH grading score in the exposed basilar cistern and the brain water content of each group were counted,and the microglia and its subtypes were detected by immunofluorescence double labeling method.The levels of inflammatory factors IL-4,IL-13,IL-1,IL-6 and TNF-αwere detected by ELISA.The blood-brain barrier-associated proteins Occludin,ZO-1 and apoptosis-related proteins caspase-3,Bax,and Bcl-2 were detected by Western blotting.Results Compared with the sham group,the neurological function score decreased,and the brain water content and SAH grading score increased in the SAH group(P<0.05).the number of microglia and content of M1 type cells increased(P<0.05),and content of M2 type cells had no change significantly in the brain tissues in the SAH group(P>0.05);the level of IL-13 decreased,the levels of IL-1,IL-6 and TNF-αincreased(all P<0.05),and the level of IL-4 had no change in the brain tissues in the SAH group(P>0.05);the protein expression levels of Occludin,ZO-1,and Bcl-2 decreased,and expression of caspase-3,Bax protein and ratio of Bax/Bcl-2 increased in the brain tissues in the SAH group.Compared with the SAH group,the neurological function scores increased,the brain water content decreased(P<0.05),and the SAH grading score had no change in the SAH+Dex group(P>0.05).The number of microglia and content of M1 type cells decreased,the content of M2 type cells increased in the brain tissues in the SAH+Dex group(P<0.05);the levels of IL-4 and IL-13 increased,and the levels of IL-1,IL-6 and TNF-αdecreased in brain tissues in the SAH+Dex group(all P<0.05);the expression levels of Occludin,ZO-1 and Bcl-2 protein increased,and the expression levels of caspase-3,Bax protein and ratio of Bax/Bcl-2 decreased in brain tissues in the SAH+Dex group(all P<0.05).Conclusion Dex has neuroprotective effects on rats after SAH,and the mechanism may be related to repairing BBB,regulating subtypes of microglia,inhibiting the release of pro-inflammatory factors,and decreasing apoptosis.