右美托咪定减轻蛛网膜下腔出血大鼠早期脑损伤的机制分析

Mechanism Analysis of Dexmedetomidine Attenuating Early Brain Injury in Rats with Subarachnoid Hemorrhage

目的:探究右美托咪定(DEX)减轻蛛网膜下腔出血(SAH)大鼠早期脑损伤的作用机制。方法:选取90只雄性Sprague-Dawley大鼠,随机分为假手术组(Sham组)、SAH模型组(建立SAH模型)、DEX组(建立SAH模型后6h给予DEX治疗),每组30只。分别在建模后24、48、72h对大鼠进行神经功能评分,后每组处死10只大鼠,取脑组织进行干湿重测定,并通过苏木素-伊红(HE)染色检测脑组织病理情况。应用酶联免疫吸附实验(ELISA)检测脑组织中白细胞介素1β(IL-1β)和白介素-18(IL-18)的表达水平。通过实时荧光定量PCR(qPCR)和蛋白质免疫印迹(WB)技术分别检测脑组织中NOD样受体热蛋白结构域相关蛋白3(NLRP3)、凋亡相关斑点样蛋白(ASC)、半胱氨酸依赖的天冬氨酸特异性蛋白酶1(Caspase-1)、紧密连接蛋白5(Claudin-5)的表达水平。结果:与Sham组比较,SAH模型组和DEX组大鼠在建模后24、48、72h的神经功能评分、脑组织水含量、脑海马体组织IL-1β、IL-18以及NLRP3、ASC、Caspase-1 mRNA和蛋白水平均升高,脑海马体组织Claudin-5mRNA和蛋白水平均降低;与SAH模型组比较,DEX组大鼠在建模后48、72h的神经功能评分、脑组织水含量、脑海马体组织IL-1β、IL-18以及NLRP3、ASC、Caspase-1 mRNA和蛋白水平均降低,脑海马体组织Claudin-5mRNA和蛋白水平均升高(P<0.01)。HE染色显示,Sham组大鼠脑组织结构完整,细胞排列正常,无坏死凋亡。SAH模型组则呈现细胞排列紊乱,显著坏死凋亡,脑组织多病灶坏死。DEX组相较于SAH组,坏死病灶减少,细胞坏死情况改善(P<0.05)。结论:DEX通过抑制NLRP3信号通路减少炎症反应,进而减轻SAH大鼠早期脑损伤。

Objective:To explore the mechanism of dexmedetomidine(DEX)in reducing early brain injury in rats with subarachnoid hemorrhage.Method:Ninety male Sprague-Dawley rats were selected and randomly divided into sham operation group(Sham group),subarachnoid haemorrhage model group(SAH model group),and DEX group,with 30 rats in each group.The brain injury model was constructed and DEX was given 6h after modeling.Neurological function scores were performed at 24,48 and 72h after modelling,respectively,after which 10 rats in each group were executed,and brain tissues were taken for wet and dry weight determination,and histopathological conditions were detected by hematoxylin-eosin(HE)staining.The expression levels of interleukin-1β(IL-1β)and interleukin-18(IL-18)in brain tissue of each group were detected by enzyme-linked immunosorbent assay(ELISA).The expression levels of NOD-like receptor hot protein domain-related protein 3(NLRP3),apoptosis-related spot-like protein(ASC),cysteine-dependent aspartate-specific protease 1(Caspase-1)and tight junction protein 5(Claudin-5)were detected by real-time fluorescence quantitative PCR(qPCR)and Western blotting(WB).Results:Compared with the Sham group,the neurological function scores,brain tissue water content,IL-1βand IL-18 in hippocampal tissue,as well as the mRNA and protein levels of NLRP3,ASC,and Caspase-1 in the SAH model group and the DEX group were all increased at 24,48,and 72 hours after modeling,while the mRNA and protein levels of Claudin-5 in hippocampal tissue were all decreased.Compared with the SAH model group,the neurological function scores,brain tissue water content,IL-1βand IL-18 in hippocampal tissue,as well as the mRNA and protein levels of NLRP3,ASC,and Caspase-1 in the DEX group were all decreased at 48 and 72 hours after modeling,and the mRNA and protein levels of Claudin-5 in hippocampal tissue were all increased(P<0.01)HE staining showed that the brain tissue structure of the Sham group was intact,the cells were arranged normally,and there was no necrosis and apoptosis.The SAH model group showed disordered cell arrangement,significant necrosis and apoptosis,and multiple lesions of brain tissue necrosis.Compared with the SAH group,the necrotic lesions were reduced and the cell necrosis was improved in the DEX group(P<0.05).Conclusion:DEX reduces inflammatory response by inhibiting the NLRP3 signalling pathway,which in turn attenuates early brain damage in subarachnoid haemorrhage rats.