电针对神经病理性疼痛大鼠痛阈及脊髓NR2B亚基表达的影响

Effect of electroacupuncture on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain

目的观察电针刺激对坐骨神经慢性压榨性损伤(CCI)引起的神经病理性疼痛模型大鼠的痛阈变化及脊髓NR2B亚基表达的影响,探讨其镇痛机理。方法健康SD雄性大鼠体质量200～280g,共40只,随机分为4组:CCI假手术组、CCI模型对照组、CCI电针组、CCI假电针组。各组大鼠于术前和术后7、13d测定热痛阈和机械痛阈。采用Western blot方法测定脊髓NR2B亚基的蛋白表达。结果 CCI模型对照组、CCI电针组和CCI假电针组大鼠痛阈术后较术前明显降低(P<0.05),电针刺激显著减轻CCI大鼠痛敏状态(P<0.05),明显抑制CCI大鼠脊髓NR2B的表达(P<0.05)。假电针组大鼠痛敏状态、脊髓NR2B的表达与模型对照组比较无统计学差异(P>0.05)。结论本研究观察到电针治疗能够提高CCI模型神经病理性疼痛大鼠的机械痛阈和热痛阈,其机制与干预大鼠脊髓背角NR2B亚基表达可能有关。

Objective To observe the effect of electroacupuncture （EA） on pain threshold and spinal NR2B subunit expression in a rat model of neuropathic pain due to chronic compression injury （CCI） of the sciatic nerve and explore the analgesic mechanism of EA. Methods Male SD rats weighing 200-280 g were randomly divided into 4 groups （n=10）,namely the sham-operated group,CCI group,EA＋CCI group,and sham EA＋CCI group. All the rats underwent tests of the mechanical withdrawal threshold and thermal threshold. On day 13 after the surgery,all the rats were decapitated to collect the L4-6 segments of the spinal cord to examine NR2B expression using Western blotting. Results The postoperative mechanical withdrawal threshold and thermal threshold were significantly lowered in CCI,EA＋CCI and sham EA＋CCI groups as compared to those before the surgery （P0.05）. EA obviously alleviated the hypersensitivity in the rats with CCI and inhibited spinal NR2B expressions （P0.05）. No significant differences were found in the mechanical withdrawal threshold,thermal threshold or spinal NR2B subunit expression between CCI group and sham EA＋CCI group （P0.05）. Conclusion EA may alleviate neuropathic hypersensitivity partially by inhibiting NR2B expression in the spinal cord of rats with neuropathic pain resulting from CCI of the sciatic nerve.