右美托咪啶通过ERK1/2 MAPK信号通路缓解七氟醚神经毒性

目的研究右美托咪啶对中枢神经系统发育期七氟醚神经毒性的影响，以及ERK1／2MAPK信号通路在其中所起的作用。方法对离体培养7d的海马神经细胞及出生后7d的Sprague-Dawley幼鼠进行七氟醚处理（3％，6h），制备七氟醚神经毒性模型。分别给予右美托咪啶或右美托咪啶＋U0126处理后，应用流式细胞仪及TUNEL染色检测细胞凋亡；应用免疫印迹检测total ERK1／2、Phospho-ERK1／2、Bax及Bcl-2的蛋白表达水平；应用Morris水迷宫检测实验动物的空间学习记忆功能变化。结果3％七氟醚处理6h使海马神经细胞凋亡增加（P=0．007），应用右美托咪啶则可明显缓解七氟醚神经毒性（P=0．032）。七氟醚处理可降低Phospho-ERK1／2及Bcl-2的蛋白表达（P〈0．05），增加Bax的蛋白表达（P〈0．05）；右美托咪啶可增加Phospho-ERK11／2及Bcl-2表达（P〈0．05），降低Bax表达水平（P〈0．05）。右美托咪啶的神经保护作用可被U0126所逆转。此外，右美托咪啶还明显缓解发育期七氟醚处理引起的空间学习记忆功能异常。结论右美托咪啶可缓解七氟醚神经毒性，其机制可能与ERK1／2MAPK信号通路有关。

Dexmedetomidine Prevents Sevoflurane Neurotoxicity via ERK1/2 MAPK Signaling in the Developing Brain

OBJECTIVE To evaluate the effects of dexmedetomidine on sevoflurane neurotoxicity and the role of ERK1/2 MAPK signaling pathway in the developing brain. METHODS The developmental sevoflurane neurotoxicity model was prepared by exposure of primary hippocampal neurons(7 days in vitro) and Sprague-Dawley rat pups(7 postnatal days) with sevoflurane (3%, 6 h). The cells were treated with dexmedetomidine or combined with U0126. The neuronal apoptosis was analyzed by flow cytometry(FCM) and TUNEL-staining. The relative expressions of total ERK1/2, phospho-ERK1/2, Bax and Bcl-2 were detected by western blot. The spatial learning and memory abilities were determined by Morris water maze. RESULTS Sevoflurane exposure(3%, 6 h) significantly enhanced the neuronal apoptosis(P=0.007), which can be ameliorated by dexmedetomidine(P=0.032). Sevoflurane treatment decreased the expressions of Phospho-ERK1/2 and Bcl-2(P<0.05), but increased Bax(P<0.05). Administration of dexmedetomidine significantly elevated the expressions of phospho-ERK1/2 and Bcl-2, but decreased Bax(P<0.05). The neuronal protective role of dexmedetomidine was abolished by U0126. In addition, treatment with dexmedetomidine significantly improved the cognitive disorders induced by postnatal sevoflurane exposure. CONCLUSION These data indicated that application of dexmedetomidine can prevent sevoflurane neurotoxicity, and the ERK1/2 MAPK signaling pathway may be involved.