摘要
目的 探讨丝裂原活化蛋白激酶家族 (MAPK)两成员ERK1/2和JNK1/2在全脑缺血损伤中的激活及其可能的分子机制。 方法 采用四动脉结扎模型诱导SD大鼠前脑缺血 ,免疫印迹的方法观察ERK1/2和JNK1/2蛋白激酶特异性Thr和Tyr双位点磷酸化的变化及NMDA受体选择性拮抗剂对其双磷酸化的影响。结果 缺血诱导海马脑区MAPK家族蛋白激酶两成员显著去磷酸化 ,严重缺血 (30min)ERK1/2而不是JNK1/2活性反弹 ;缺血再灌注ERK1/2活性在 15min首先升至最高而JNK1/2 1h后才逐渐升至峰值 (P <0 .0 5 ) ,2 4h再灌注能诱导两者的再次激活 ,且氯胺酮能显著抑制缺血诱导的ERK1/2而不是JNK1/2的激活。 结论 前脑缺血明显诱导ERK1/2和JNK1/2的差异激活 ,提示两者可能分享不同的分子机制 ,其中ERK1/2的激活明显与NMDA受体功能上调有关。
Objective To examine ischemia-induced temporal activation of two members of mitogen-activated protein kinase (MAPK) superfamily, extracellular-signal regulated kinase (ERK1/2) and c-Jun N-terminal protein kinase (JNK1/2), and explore their molecular mechanisms underlying brain ischemia injury in vivo. Methods Brain ischemia was induced by the 4-vessel occlusion method in SD rats; MAPK activations and effect of the special antagonist on them were analysed by Western Blotting with anti-diphosphorylated MAPK antibodies. Results Albeit brain ischemia without reperfusion caused loss of ERKs and JNKs phosphorylation, 30 min ischemia could trigger the rebound of ERK1/2 but not JNK1/2 activity significantly(P<0.05). Reperfusion after ischemia contributed to the active peak of ERK1/2 at 15 min or JNK1/2 at 1 h separately, and followingly to the second activation of both at 24 h. Moreover, ketamine markedly suppressed activation of ERK1/2 but not JNK1/2 during ischemia and reperfusion(P<0.05). Conclusion ERK1/2 and JNK1/2 become activated differentially after brain ischemia episode, and the two molecular mechanisms might be various and up-regulation of NMDA receptor activity participates in ERK1/2 but not JNK1/2 activation in brain ischemia.
基金
南京医科大学科技发展基金 (NY0 3 0 66)
