戊四氮致痫大鼠中ERK信号通路的研究

Role of extracellular signal regulated protein kinase signal transduction pathway in pentylenetetrazole(PTZ)-induced seizures

目的:研究细胞外信号调节蛋白激酶(ERK)信号通路在癫痫大鼠脑内的表达规律及其意义。方法:建立戊四氮致痫大鼠模型,在痫性发作30 min、1.5 h5、h和8 h应用免疫组织化学和Western印迹法对海马ERK1、ERK2和p-ERK1/2蛋白水平的表达进行研究,并加用ERK通路阻断剂PD98059干预。结果:正常大鼠脑内有少量的ERK1和ERK2阳性神经元,未见有p-ERK1/2阳性神经元。戊四氮致痫后30min p-ERK1/2开始表达,ERK1和ERK2表达较对照组开始增强(P<0.05),1.5 h后p-ERK1/2强烈表达(P<0.05),5 h后3者的表达开始减弱。PD98059干预组ERK1/2的活化较癫痫组显著受抑(P<0.05)。Western Blot结果显示,癫痫组大鼠ERK1、ERK2和p-ERK1/2蛋白表达较对照组明显增强(P<0.05),PD98059干预组3种蛋白水平显著低于癫痫组(P<0.05)。1.5 h时点的蛋白表达水平高于其他各时点相应组(P<0.05)。同时PD98059完全抑制了大鼠的痫性发作。结论: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,并可能具有上游始动发生的作用。

Objective： To investigate the expression of extracellular signal regulated protein kinase （ERK） signal transduction pathway and its significance in the rat brain after epileptic seizures. Method： A pentylenetetrazole （PIZ）-induced seizure model was established to evaluate the phosphorylation forms of ERK1, ERK2 and neuronal damage in hippocampus by immunohistochemistry, histopathology and Western blotting methods at 30 minutes, 1.5 hours, 5 hours and 8 hours respectively after seizures. Results： In the brain of saline-treated rats, a few immunoreactivity （IR） was detected in ERK1 and ERK2, while not in p-ERK1/2. IR of p-ERK1/2 was observed in the affected rats at 30 minutes following PIE injection （ P 〈 0.05） and reached the peak at 1.5 hours （ P 〈 0.05）, and so was the IR of ERK1 and ERK2 （ P 〈 0.05）. Whereas they began to decline at 5 hours after PIE injection and descended to a lower level at 8 hours. Inhibitor of ERK pathway-PD98059 not only inhibited the epileptic activities in rats induced by PTZ, but also depressed the activation of ERK （ P 〈 0.05）. Result of Western blotting suggested that the levels of ERK1, ERK2 and p-ERK1/2 in epileptic rats increased remarkably （P 〈 0.05） and were inhibited obviously by PD98059 （P 〈 0.05）. Conclusion： ERK pathway is activated in PTZ-induced epilepsy model and takes part in the pathophysiolngical mechanism, which may be essential for initiating seizures.