电针对慢性炎性疼痛模型大鼠痛阈和脊髓背角神经肽Y表达的影响

目的:观察电针对完全弗氏佐剂(CFA)诱发的炎性疼痛模型大鼠痛阈及其脊髓背角神经肽Y(NPY)表达的影响,探讨电针“足三里(ST36)+阳陵泉(GB34)”治疗慢性炎症疼痛的作用机制。方法:将24只正常痛阈的SD雄性大鼠随机分为空白组(Saline组)、模型组(CFA组)、假电针组(CFA+sham EA组)、电针组(CFA+EA组),每组6只,实验大鼠后足底注射CFA建立慢性炎性疼痛模型,在造模成功后第6天,开始电针“ST36+GB34”频率2 Hz、幅度1 mA、时间20 min、连续波,每天1次,连续治疗5 d,用热板试验、von Frey测试检测实验大鼠热痛阈和机械痛阈的改变,用免疫组织化学方法检查脊髓背角NPY表达变化。结果:电针治疗慢性炎性疼痛模型大鼠可以逆转CFA引起的热痛觉过敏(P<0.01)和触觉超敏(P<0.05),脊髓背角Ⅰ-Ⅱ层NPY表达增加,参与CFA诱发慢性炎性疼痛的形成(P<0.01),电针进一步诱导模型大鼠脊髓背角Ⅰ-Ⅱ层NPY表达增加(P<0.001)。结论:NPY是一种抗伤害感受的神经肽,电针治疗可以缓解CFA模型大鼠的疼痛和进一步诱发脊髓背角中NPY表达增加发挥抗伤害作用。

Effect of Electroacupuncture on Pain Threshold and Expression of Neuropeptide Y in Spinal Dorsal Horn in Rats with Chronic Inflammatory Pain

Objective:To observe the effects of electroacupuncture on the pain threshold and the expression of neuropeptide Y(NPY) in rats with inflammatory pain induced by complete Freund's adjuvant(CFA),and to explore the therapeutic mechanism of needling "Zusanli(ST 36) + Yanglingquan(GB 34)" with electroacupuncture in the treatment of chronic inflammatory pain. Methods:Twenty-four SD male rats with nor mal pain threshold were randomly divided into blank group(saline group),model group(CFA group),sham electroacupuncture group(CFA + sham EA group)and electroacupuncture group(CFA + EA group),6 rats in each group. The rat was injected with CFA to establish a chronic inflammatory pain model. On the 6 th day after the modeling,the electroacupuncture was performed at "ST 36 + GB 34" with the frequency at 2 Hz,the amplitude of 1 mA,the time of 20 min,and continuous waves,once a day for 5 days. Hot plate test and von Frey test were performed to detect changes in thermal pain threshold and mechanical pain threshold,and immunohistochemical methods were used to examine the expression of NPY in spinal dorsal horn. Results:Electroacupuncture treatment for rat with chronic inflammatory pain could reverse thermal hyperalgesia(P<0.01) and tactile hypersensitivity(P<0.05) induced by CFA. Increased expression of NPY in the I-II layer of spinal dorsal horn was involved in the CFA-induced chronic inflammatory pain(P<0.01),and electroacupuncture could further induce the expression of NPY in the I-II layer of spinal dorsal horn in model rats(P<0.001). Conclusion:NPY is an anti-nociceptive neuropeptide,and electroacupuncture treatment could alleviate the pain of CFA rat model and further induce the increase of NPY expression in spinal dorsal horn.