腕踝针对癌痛大鼠的抗吗啡耐受作用及其神经生物学机制研究

Morphine tolerance is a key problem to be resolved in treatment of cancer pain. Wrist-ankle acupuncture (WAA), a kind of painless subcutaneous acupuncture without needling sensation, is easily to be accepted by patients. WAA combined with morphine can produce promising analgesic effects and reduce the side effects of morphine, and therefore has potential priorities for future use, but the action mechanisms are unknown. Studies demonstrated that electroacupuncture (EA) combined with morphine can enhance the analgesic effects of EA or morphine used alone, and the effects of EA in attenuating morphine tolerance are mediated by μ opioid receptor. WAA is a needling therapy different from EA. Are the action mechanisms of WAA different from those of EA? In order to answer this question, based on our previous research outcomes and in comparison with EA, we will observe the effects of WAA against morphine tolerance and the influences of the antagonists of μ opioid receptor and 5-HT3 receptor on the WAA effects in a rat model of cancer pain by testing the pain behaviors of the rats. We will also observe the changes of the contents of endomorphins and β-endorphin, the expressions and functions of μ opioid receptors, the contents of 5-HT, and the expressions of 5-HT3 receptor in rostral ventromedial medulla (RVM) and spinal cords of the rats using immunohistochemical and molecular biological methods, so as to investigate the neurobiological mechanisms of WAA in a perspective of μ opioid receptor-mediated descending inhibition in RVM-spinal cord pathway, a key part of the pain-modulating system. The ideas of this study came from our clinical practice, and meet the demands of the clinical work. The results of this study will provide scientific evidence for evaluating the treatment efficacy of WAA, and hence promote the broader use of WAA in treatment of cancer pain. The results will also enrich the knowledge about the mechanisms of acupuncture analgesia.

吗啡耐受是癌痛治疗需解决的关键问题。腕踝针属皮下无痛针刺法，患者易接受，与吗啡合用镇痛效果良好，且能减轻吗啡的副作用，有很好的应用前景，但作用机制不明。研究表明，电针与吗啡合用能加强镇痛、通过μ受体介导减轻吗啡耐受。腕踝针是不同于电针的针刺治疗，作用机制是否不同？本项目在已有工作基础上，用行为学和药理学方法观察腕踝针抗癌痛大鼠吗啡耐受的效应及μ受体和5-HT3受体拮抗剂对该效应的影响，用免疫组化和分子生物学方法观察延髓头端腹内侧区(RVM)和脊髓中内吗啡肽和β-内啡呔含量、μ受体数量和功能、5-HT及5-HT3受体的变化，从痛觉调制系统关键的RVM-脊髓通路中μ受体介导的痛觉下行抑制角度，探讨腕踝针效应的神经生物学机制，并同时与电针比较。本项目研究思路源于临床，符合临床需求，研究结果将为腕踝针的疗效评价提供科学依据，推动腕踝针在癌痛治疗中的推广应用，同时也将丰富人们对针刺镇痛原理的认识。

据世界卫生组织统计全球每天有550万人忍受癌痛的折磨，其中60%以上为中、重度疼痛。吗啡是治疗中、重度癌痛的首选药物，但连续使用一段时间后会形成耐受。如何减轻吗啡镇痛耐受是临床癌痛治疗和癌痛基础研究需解决的关键问题。针刺疗法在临床上常常与阿片类药物联合应用治疗癌痛。针药结合镇痛及减轻吗啡耐受有望成为临床镇痛一个新的契机。.本研究主要通过行为学和药理学方法观察腕踝针和电针抗大鼠癌痛的效应以及μ受体和5-HT3受体拮抗剂对该效应的影响，用免疫组化方法观察脊髓中μ受体、5-HT3受体、腺苷A1受体的变化，探讨腕踝针和电针镇痛效应的神经生物学机制。.研究采用大鼠胫骨内接种Walker 256乳腺癌细胞建立癌痛模型。实验结果表明大鼠在接种7天后双侧后肢机械性痛阈显著降低，腕踝针治疗癌痛大鼠机械性痛敏效果不佳，而电针可以改善大鼠接种同侧后肢的机械性痛敏（肿瘤接种后的第10天开始至第16天，电针组大鼠同侧后肢的机械性痛阈高于癌痛组）。而大鼠鞘内注射μ受体拮抗剂CTOP可以阻断电针的镇痛效应（在第9天及第12-16天，电针预处理CTOP组大鼠的机械性痛阈低于电针预处理生理盐水组），说明电针缓解癌痛大鼠机械性痛敏与μ受体有关。μ受体和腺苷A1受体在骨癌痛大鼠脊髓L4-6节段中的表达下调，电针治疗后表达上调；然而预处理CTOP电针治疗后μ受体和腺苷A1受体表达不再上调；同时5-HT3受体在癌痛大鼠脊髓表达上调，电针治疗后下调。电针能在一定程度上增强吗啡镇痛效应，但能否缓解吗啡镇痛耐受还需进一步实验确定。.本项目研究思路源于临床，符合临床需求，研究结果将为针刺的疗效评价提供科学依据，推动针刺在癌痛治疗中的推广应用，同时也将丰富人们对针刺镇痛原理的认识。