CB2R负性调控MAPK信号通路——从脊髓敏化角度研究电针治疗骨性关节炎慢性疼痛的康复新机制

Chronic pain of osteoarthritis (OA) is an important reason for the loss of labor force in people over 50 years of age. The effect of electroacupuncture on OA chronic pain is reliable, but the mechanism remains unclear. Previous studies show that central sensitization of spinal level may contribute to the chronic process of OA pain, and cannabinoid receptor 2(CB2R) plays a regulatory role in spinal sensitization. Taking the viewpoint that spinal sensitization participates in the OA chronic pain as an entry point, this research focuses on  the mechanism of electroacupuncture on chronic pain in OA, and the hypothesis is put forward that the effects of electroacupuncture in inhibiting OA chronic pain is relevant to the fact that electroacupuncture could negatively regulate MAPK signaling pathway through CB2R, and thereby inhibit spinal sensitization. In this research, MIA-induced rat model of OA joint pain is to be used as the research object, electroacupuncture of Nei xi yan and Yanglingquan points is to be selected as interventions, and that the regulating effects of electroacupuncture on spinal sensitization of OA chronic pain and its correlation with the activity of spinal cord CB2R and MAPK signaling pathway are to be observed at different level and different time through the methods of immunofluorescence, ELISA, real time quantitative PCR as well as Western blot. It is expected to elucidate the mechanism of electroacupuncture on inhibition of OA chronic pain from the aspect of spinal sensitization，and therefore to provide a new target for the research of electroacupuncture in treatment of chronic pain of OA and provide new scientific basis for clinical application of electroacupuncture on chronic pain of OA.

骨性关节炎(OA)慢性疼痛是导致50岁以上人群劳动力丧失的重要原因，电针治疗OA慢性疼痛疗效确切，但相关机制仍不明确。研究发现，脊髓敏化参与OA疼痛慢性化进程，大麻素受体2(CB2R)对脊髓敏化具有调控作用。本课题拟从“脊髓敏化参与OA慢性疼痛”切入，研究电针治疗OA慢性疼痛的作用机制，提出“电针通过CB2R负性调控MAPK信号通路，进而抑制脊髓敏化发挥OA镇痛效应”的假说。研究将以MIA诱导的膝OA慢性疼痛大鼠为研究对象，采用“阳陵泉、内膝眼”穴电针作为干预手段，利用免疫荧光、ELISA、实时荧光定量PCR和Western blot等现代检测技术，从不同层次和不同时间观察电针对OA脊髓敏化的调控作用及其与脊髓CB2R活性和MAPK信号通路的相关性。有望从脊髓敏化角度阐明电针抑制OA慢性疼痛的作用机制，为电针治疗OA慢性疼痛提供新的研究靶点，为临床应用电针治疗OA慢性疼痛提供新的科学依据。

疼痛是骨性关节炎(OA)的首发症状，也是导致OA患者丧失劳动力的重要原因，电针治疗OA慢性疼痛疗效确切，但相关机制仍不明确。OA慢性疼痛具有神经病理性疼痛的性质，脊髓敏化在OA慢性疼痛的发生及维持中发挥了重要作用。脊髓背角感觉神经元高敏及小胶质细胞活化是脊髓敏化的重要特征。大麻素受体2(CB2R)对脊髓敏化具有调控作用，可通过抑制MAPK信号通路发挥镇痛效应。本课题基于以上研究发现，从“脊髓敏化参与OA慢性疼痛”切入，研究电针干预是否通过脊髓背角CB2R负性调控MAPK信号通路，发挥抑制脊髓敏化进而达到镇痛效应的作用。实验以谷氨酸钠碘乙酸(MIA)膝关节腔注射法诱导的膝OA(KOA)大鼠为研究对象，采用“阳陵泉、内膝眼”穴电针作为干预手段，利用痛性行为学评价、免疫荧光、ELISA、明胶酶谱和Western-blot等检测技术，观察了电针对KOA脊髓敏化的调控作用及其与脊髓CB2R活性和MAPK信号通路的相关性。实验结果显示，电针干预可显著缓解KOA大鼠的痛性行为，上调背角神经元CB2R的表达，抑制背角神经元MAPK信号通路关键分子P38和ERK的表达，抑制背角小胶质细胞的活性及背角IL-1β、IL-6、TNF-ɑ、PGE2、CGRP和P物质等炎性介质及细胞因子的释放。以上实验结果表明，电针干预对KOA大鼠的镇痛效应与电针通过上调脊髓背角神经元CB2R活性，抑制背角神经元MAPK信号通路的活性，进而抑制脊髓敏化密切相关。这一研究发现从神经病理学角度揭示了电针对OA慢性疼痛镇痛效应的中枢神经机制，为电针在OA疼痛康复中的应用提供新的科学依据，为进一步研究电针治疗OA疼痛奠定基础和提供思路。