弥漫性脑损伤细胞外信号调节激酶1／2信号通路的激活及意义

Feature and role of extracellular signal-regulated kinase1/2 pathway activation in acute traumatic diffuse brain injury of rats

目的探讨弥漫性脑损伤（DBI）时细胞外信号调节激酶1／2（ERK1／2）信号通路激活特点及特异性阻滞剂U0126对损伤神经元的作用。方法制作大鼠DBI模型，Western blot法检测损伤脑组织磷酸化ERK1／2的表达，免疫组化法检测磷酸化ERK1／2、神经元特异性磷酸烯醇化酶（NSE）表达，透射电镜下观察U0126对损伤神经元的作用。结果DBI后磷酸化ERK1／2表达显著增高，持续高水平表达至72h。U0126剂量依赖性抑制磷酸化ERK1／2表达。U0126组12～24h时相点NSE较DBI组明显增高。透射电镜显示U0126组神经元损伤较轻。结论大鼠DBI后ERK1／2通路被过度和持久激活，阻滞其过度激活可减轻继发性神经元损伤。

Objective To explore the feature of extracellular signal-regulated kinase1/2 （ERK1/2） pathway activation in traumatic diffuse brain injury （DBI） of rats and the role of U0126, a specific inhibitor of ERK1/2 pathway, on injured neurons. Methods Rats were subjected to traumatic DBI by Marmaroug free falling-body method. Western blot analysis and immunochemistry were used to evaluate the expression level and spatial distribution of phosphorylated ERK1/2（phospho-ERK1/2 ） in injured brain tissue. NSE expression was evaluated by immunochemistry immunostaining. Transmission electron microscope was used to observe the microstructure of UO126 injured neurons. Results Western blots analysis illustrated that phospho-ERK1/2 significantly increased after DBI, peaking at minute 5, and sustained for 72 hours. Treatment with U0126 effectively prevented the activation of ERK1/2 in a dose-dependent fashion （ P 〈 0. 05 ）. Immunochemistry staining results showed that average optical density of NSE was higher in UO126 group than that in DBI group. The protective role of U0126 on neuron injury was observed by transmission electron microscope. Conelusion ERK1/2 pathway is sustained and over-activated in DBI after trauma. Inhibition of the over-activated pathway by U0126 can protect neuron against secondary injury.