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目的:研究细胞外信号调节激酶(ERK)、天冬氨酸特异性半胱氨酸蛋白酶-8(caspase-8)在蛛网膜下腔出血(SAH)后早期脑损伤中的作用,并探讨ERK特异性抑制剂U0126通过此途径发挥作用的保护机制。方法:采用稳定的非开颅血管内穿线法制备小鼠SAH模型,并于术前30 min经尾静脉给予U0126(0.1 mg/kg),分别在术后12、24、48 h 3个时相点取右侧大脑动脉标本,HE染色观察大脑动脉的形态改变,并检测大脑中动脉(MCA)的直径变化;应用免疫印迹法检测各组p-ERK1/2、caspase-8蛋白表达,TUNEL法检测MCA内皮细胞凋亡。结果:模型组小鼠MCA出现严重血管痉挛,直径减小,p-ERK1/2、caspase-8蛋白均有不同程度增强,凋亡细胞增多。与模型组比较,治疗组小鼠各时相点上述3项指标的表达均呈不同程度下调,MCA管径增加,脑血管痉挛缓解。SAH 12～48 h时p-ERK1/2与caspase-8的表达呈正相关。结论:SAH后ERK表达增强可通过激活caspase-8信号途径诱导大脑动脉内皮细胞凋亡;U0126可减少大脑动脉内皮细胞凋亡,其机制之一可能是通过阻抑ERK通路活化实现的。
Objective: To investigate the role of extracellular signal-regulated kinase (ERK) and caspase-8 in early brain injury following subarachnoid hemorrhage (SAH) and to explore the role of ERK The specific inhibitor U0126 through this pathway to play a role in the protection mechanism. Methods: SAH model was established by stable non-craniotomy intra-peritoneal instillation method. U0126 (0.1 mg / kg) was injected via caudal vein 30 minutes before operation. The rats were sacrificed at 12, 24, The morphological changes of the cerebral arteries were observed by HE staining and the diameter of the middle cerebral artery (MCA) was measured. The expressions of p-ERK1 / 2 and caspase-8 were detected by Western blotting, TUNEL assay Detection of MCA endothelial cell apoptosis. Results: MCA in model group showed severe vasospasm and decreased in diameter. The expressions of p-ERK1 / 2 and caspase-8 protein increased to different degrees and apoptotic cells increased. Compared with the model group, the expression of the above three indexes of mice in the treatment group were all decreased to different degrees, the diameter of MCA increased, and the ease of cerebral vasospasm was relieved. The expression of p-ERK1 / 2 and caspase-8 was positively correlated between 12 h and 48 h after SAH. CONCLUSION: Enhanced expression of ERK after SAH induces apoptosis of cerebral arterial endothelial cells by activating caspase-8 signaling pathway. U0126 can reduce apoptosis of cerebral arterial endothelial cells. One of the mechanisms may be through the inhibition of ERK pathway activation.