ERK信号转导通路在癫痫大鼠脑部作用的研究

目的:研究ERK信号转导通路在癫痫发病机制中的作用。方法:将54只雄性Wistar大鼠分为正常组6只,假模型组和癫痫组各24只,后2组按大鼠存活时间各分为30 min组1、.5 h组5、h组和8 h组各6只。癫痫组腹腔注射戊四氮制作癫痫大鼠模型,假模型组以生理盐水代替戊四氮腹腔注射。应用免疫组化染色、组织病理学染色及Western blot检测,分别检测各组大鼠大脑皮质ERK1、ERK2和p-ERK1/2的表达及神经元的损伤情况。结果:免疫组化染色结果显示正常组和假模型组大鼠脑内有少量的ERK1和ERK2阳性神经元,无p-ERK1/2阳性神经元;癫痫组致痫30 min后脑内p-ERK1/2阳性细胞开始出现,同时ERK1和ERK2阳性细胞较正常水平也有增多,1.5 h后3种阳性细胞均明显增多(P<0.05),5 h后3者开始减少,8 h后仅见少量阳性神经元。组织病理学染色示癫痫组皮质出现散在异常神经元。Western blot检测显示痫性发作各时点大鼠皮质内ERK1、ERK2和p-ERK1/2蛋白表达较正常水平显著增多(P<0.05),1.5 h时点组的蛋白表达水平高于其他各时点组(P<0.05)。结论:皮质ERK信号途径在戊四氮致痫模型中被激活,参与癫痫发作的病理生理过程。

Study of ERK Signal Transduction Pathway in Rats with Pentylenetetrazole (PTZ)-induced Seizures

Objective: To investigate the expression of ERK signal transduction pathway and its significance in the cerebral cortex of rats after epileptic seizures.Methods: A pentylenetetrazole(PTZ)-induced seizure model was established to evaluate the expression of ERK1 and ERK2 as well as the phosphorylation form of ERK1/2-p-ERK1/2 in cerebral cortex by immunohistochemistry and Western blot at 30 min,1.5h,5h and 8h respectively after seizures.Neuronal damage was evaluated by histopathology.Results: p-ERK1/2 immunoreactivity(IR) was not detected in the brain of saline-treated rats while ERK1 and ERK2 showed a little IR.IR of p-ERK1/2 began to be observed in the affected rats at 30 min following PTZ injection(IR=9.68±1.29,compared with the empty control group,P<0.05),and reached the peak at 1.5h(IR=21.68±3.09,compared with the empty control group,P<0.05).Both ERK1 and ERK2 IR also began to increase in(30 min) group and had obvious increase in 1.5 h groups when compared with the control group(P<0.05).They all declined 5h after PTZ injection and dropped to a lower level 8h later.Injured neurons were also present in histopathological examination.Western blots showed that the level of ERK1,ERK2 and p-ERK1/2 in cerebral cortex of epileptic rats all increased remarkably compared with the saline-treated rats(P<0.05) in different time groups.The expression of the all three proteins was higher in 1.5h group than in the other groups.Conclusion: ERK pathway in cerebral cortex was activated to take part in the pathophysiological mechanism in PTZ-induced epilepsy model,and the pathway might play an important role in initiating seizures.