从MAPK／ERK、p38信号通路探讨电针对大鼠分娩疼痛的镇痛机制

Labor pain is one of a variety of pains which possess the highest pain threshold. So far, there is no satisfactory antalgic method for the treatment of labor pain. Recently, cell signaling has been received considerable attention among the researches on labor pain. Studies indicated that the MAPK/ERK, p38 pathways play an important role in the occurrence and development of labor pain. Acupuncture has a long history in treating pain with good effect, but the mechanisms remain unclear. Previous studies indicated that electro-acupuncture effectively treat labor pain involving the regulation of dynorphin (DYN) and prostaglandin E2 (PGE2). Based on prophase researches, the present study aims to observe the antalgic effect of electro-acupuncture on rats with delivery when compared to analgesic drug, and to analyze the gene and protein expression of signal molecules such as Raf, ERK, CREB, MKP-1, p38 and PLA2, and the effector molecules of DYN and PGE2 in brain gray matter parietal area, lumbar enlargement of spinal cord segments and myometrium of rats by Western Blot, Real-time PCR and so on. The findings will reveal the mechanisms of antalgic effect of electro-acupuncture on labor pain, and provide scientific evidence for the treatment of labor pain using electro-acupuncture.

分娩疼痛是世界上疼痛阈值最高的疼痛种类之一，迄今为止，尚无令人满意的镇痛方法。近年来，细胞内信号转导途径在研究分娩疼痛方面受到越来越多的关注。研究表明，MAPK/ERK、p38通路对分娩疼痛的发生发展起着重要的作用。 针刺镇痛历史悠久，疗效明显，但其潜在机制尚未清楚，前期课题研究显示电针对分娩镇痛效果明显及对强啡肽(DYN)、前列腺素E2(PGE2)有调控作用。本项目在此基础上，观察电针对分娩大鼠的镇痛作用，并以镇痛药物为对照，基于MAPK /ERK、p38信号通路，应用Western blot，Real-time PCR等技术，探讨电针对分娩大鼠大脑灰质顶叶区、脊髓腰膨大段及子宫肌层组织信号分子Raf、ERK 、CREB 、MKP-1、p38、PLA2及效应分子DYN、PGE2的蛋白及基因表达的影响，从细胞分子水平揭示电针镇痛的潜在作用机制，为电针分娩镇痛提供科学依据。

研究背景：分娩疼痛在医学疼痛指数中仅次于烧伤灼痛而居第二。针灸镇痛对母婴安全无副作用，本研究在前期研究基础上，并基于MAPK信号通路，探讨针灸镇痛机制。内容及方法：对120例模型大鼠随机分EA EX-B2、EA SP6+ LI4， Remifentanil及Control等四组，每组30例。热水甩尾检测大鼠痛阈；Western blot、Real-time PCR检测大鼠中枢及靶器官信号分子与效应分子蛋白与基因表达；ELISA检测电针大鼠不同时间段血清DYN与 PGE2浓度。结果（1）EX-B2、SP6+ LI4使大鼠痛阈值升高，在电针后30min、 60min、120min，DYN浓度表达水平与时间呈负相关性，PGE2呈正相关性。（2）信号分子C-Raf、ERK 1、CREB及MKP-1、p38、Ma-PLA2-IV等基因与蛋白在四组大鼠大脑灰质表达组间差异无明显；而在脊髓膨大段组间差异明显，由高到低依次为Control> EA EX-B2/ EA SP6+ LI4>Remifentanil（4）四组大鼠子宫肌组织中DYN基因与蛋白表达水平，与Control比较EX-B2、SP6+ LI4及Remifentanil高；而PGER2与Control比较EX-B2、SP6+ LI4及Remifentanil低。DYN与PGER2基因与表达水平呈负相关性。. 结论： 电针介导MAPK/P38、ERK信号传导通路参与分娩镇痛作用及其机制可能是通过激活脊髓MKP1及MAPK／ERK、p38通路磷酸化分子，抑制其下游信号分子C-Raf ， ERK 1、CREB、及p38 、Ma-PLA2-IV等分子基因与蛋白表达水平，降低其活化作用；提高靶器官（子宫肌层组织）中，MAPK／ERK、p38信号通路效应分子DYN及下调PGE2基因与蛋白表达水平有关。