ERK5在大鼠脑梗死和脑出血转化中的激活表达

ACTIVATION OF ERK5 IN RATS WITH CEREBRAL INFARCTION OR HEMORRHAGIC TRANSFORMATION

目的观察持续性脑缺血及脑出血转化时大鼠脑组织中细胞外信号调节激酶5(ERK5)的激活表达情况。方法 Sprague-Dawley大鼠120只,随机分为持续性缺血组、脑出血性转化组、假手术组,各40例。线栓法建立大鼠大脑中动脉栓塞模型。出血性转化组分别在大脑中动脉栓塞4、8、16、24h后拔除栓线,再灌注24h;持续性缺血组在4、8、16、24h后不拔除栓线继续栓塞24h。假手术组手术过程和时间与出血性转化组相同,但不栓塞大脑中动脉。术后2h应用BERDERSON评分法评价各组大鼠神经功能评分,采用TTC染色法观察各组大鼠脑梗死及出血情况;Western blotting检测各组大鼠磷酸化ERK5(p-ERK5)及ERK5的蛋白激活表达水平。结果持续性缺血组和脑出血性转化组大鼠均表现出不同程度的神经功能障碍。TTC染色显示,脑出血性转化组8、16、24h时在脑梗死范围内出现了不同程度的出血转化。Western blotting结果显示,持续性缺血组和脑出血性转化组各时间点p-ERK5蛋白表达量增高,与假手术组相比差异有统计学意义(F=37.02~91.85,q=4.58~18.66,P<0.05)。脑出血性转化组8、16、24h的p-ERK5蛋白表达量与4h比较、8、24h与16h比较差异均有显著意义(F=39.47,q=5.90~15.24,P<0.05)。持续性缺血组8、16、24h的p-ERK5表达量较4h显著升高,差异有显著意义(F=7.81,q=4.59~6.46,P<0.05)。3组组内不同时间点以及3组间ERK5蛋白表达差异无统计学意义(P>0.05)。结论大鼠脑缺血及脑出血转化可以诱导ERK5的激活,参与脑缺血与出血转化过程并发挥重要作用。

Objective To investigate the activation of extracellular signal-regulated kinase 5（ERK5）in rats with cerebral infarction or hemorrhagic transformation（HT）. Methods A total of 120 healthy male adult Sprague-Dawley rats were equally and randomly divided into three groups：permanent ischemia group,HT group,and sham-operation group.A model of middle cerebral artery occlusion in rats was established by suture method.In the HT group,the suture was removed at 4,8,16,and 24 hafter occlusion,followed by reperfusion for 24 h;in the permanent ischemia group,the suture was not removed at 4,8,16,and 24 hafter occlusion,followed by occlusion for 24 h.The sham-operation group underwent the same procedures as the HT group except occlusion of the middle cerebral artery.The BEDERSON score was used to evaluate the neurological function at 2 h after surgery.TTC staining was used to evaluate cerebral infarction and hemorrhage.The expression of ERK5 and phosphorylated ERK5（p-ERK5）were measured by Western blot. Results Rats in the permanent ischemia group and the HT group showed neurological deficit to varying degrees.TTC staining revealed that varying degrees of HT（within the extent of cerebral infarction）was pre-sent at 8,16,and 24 hin the HT group.Western blot results showed that the expression of p-ERK5 in the permanent ischemia group and the HT group increased and were significantly higher than that in the sham-operation group（F=37.02-91.85,q=4.58-18.66,P〈0.05）.In the HT group,there were significant differences in the expression of p-ERK5 at 8,16,and 24 hvs at 4 hand at 8 and 24 hvs at 16 h（F=39.47,q=5.90-15.24,P〈0.05）.The expression of p-ERK5 in the permanent ischemia group significantly increased at 8,16,and 24 hvs at 4 h（F=7.81,q=4.59-6.46,P〈0.05）.There were no significant differences in the expression of ERK5 at different time points in each group and between the three groups at each time point（P 0.05）.Conclusion The activation of ERK5 can be induced by cerebral ischemia and HT in rats,so that ERK5 is involved in cerebral ischemia and HT and plays an important role.