电针对神经病理性疼痛大鼠脊髓小胶质细胞活化的影响

Effects of electroacupuncture on activation of microglia cells in spinal cord in rats with neuropathic pain

目的:观察电针对神经病理性疼痛(neuropathic pain,NP)大鼠脊髓L4-L6中小胶质细胞活化的影响,探讨电针是否通过抑制小胶质细胞活化影响脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)的表达达到镇痛效应。方法:将40只成年雄性SD大鼠,随机分为正常组、假模组、模型组、电针组,每组10只。正常组大鼠不做处理,假模组暴露坐骨神经2~3min,不打结,余大鼠建立慢性坐骨神经压迫性损伤(chronic constrictive injury,CCI)疼痛模型。电针组于造模后7d开始电针"足三里""阳陵泉",每次30min,每天1次,连续7d;余组仅予固定,不做治疗。各组于造模前及造模后3、5、7、10、12、14d分别测量大鼠患侧机械缩足反射阈值(MWT)和热缩足反射潜伏期(TWL)。术后14d处死大鼠,对脊髓L4-L6行免疫组化观察,检测小胶质细胞(Iba1)和BDNF蛋白表达,并采用实时荧光定量PCR检测脊髓L4-L6中BDNF mRNA的表达。结果:与假模组相比,模型组大鼠痛阈明显降低(P<0.01),出现痛觉过敏;电针干预后,电针组较模型组痛阈明显升高(P<0.01);术后14d,模型组脊髓L4-L6中Iba1、BDNF蛋白表达及BDNF mRNA水平高于正常组和假模组,电针组脊髓L4-L6中Iba1、BDNF蛋白表达及BDNF mRNA水平较模型组显著减少(均P<0.01)。结论:电针对神经病理性疼痛的镇痛效果可能是通过抑制大鼠脊髓中小胶质细胞活化从而减少BDNF的表达产生作用。

Objective To observe the effects of electroacupuncture（EA）on the activation of microglia cells in the L4 to L6spinal cord in rats with neuropathic pain,so as to investigate whether EA could inhibit the activation of spinal microglial cells and regulate the expression of brain-derived neurotrophic factor（BDNF）to achieve the analgesic effect.Methods Forty male Sprague Dawley rats were randomly divided into a normal group,a shammodel group,a model group and an EA group,10 rats in each one.The rats in the normal group received no treatment;the rats in sham-model group were treated with operation to exposure sciatic nerve for 2to 3min（no knot）;the rats in the remaining groups were treated with model establishment of chronic constrictive injury（CCI）.7days after model establishment,the rats in the EA group were treated with EA at ＂Zusanli＂（ST 36）and ＂Yanglingquan＂（GB 34）,30 min per time,once a day for consecutive 7days.Only immobilization was used in the remaining groups the mechanical withdrawal threshold（MWT）and thermal withdrawal latency（TWL）of affected side feet were respectively measured before model establishment and 3days,5days,7days,10 days,12days and14 days after model establishment;14days after model establishment,rats were sacrificed;the immunohistochemical method was used to measure the expression of Iba1 and BDNF in the sample of L4 to L6spinal cord;real-time fluorescent quantitative PCR was used to measure the expression BDNF mRNA.Results Compared with the sham-model group,the pain threshold was decreased significantly in the model group（P〈0.05）,leading to hyperpathia.After EA treatment,compared with the model group,the pain threshold was increased significantly in the EA group（P〈0.05）.14 days after operation,the microglia cells in the L4 to L6spinal cord,expression of BDNF and level of mRNA in the model group were significantly higher than those in the normal group and sham-model group（all P〈0.01）;those in the EA group were significantly lower than those in the model group（all P〈0.01）.Conclusion The analgesic effect on neuropathic pain is likely to be achieved by EA through inhibiting the activation of spinal microglia cells and down-regulating the expression of BDNF.