电针对慢性神经源性痛大鼠痛行为反应和脊髓背角NOS的影响

目的:观察慢性神经源性痛时的痛行为反应和脊髓背角NOS活性变化以及电针对它们的影响作用。方法:SD大鼠72只分为对照组(n=24,假手术)、模型组(n=24,手术)、电针组(n=24,手术+电针)。慢性神经源性痛模型参照Mosconi氏的大鼠坐骨神经慢性压迫法制作。电针取“环跳”和“阳陵泉”穴区。痛阈测定采用热辐射测痛法,分别于术后第2、4、7、14、28 d进行实验观察,NOS活性观察用NADPH-d酶组织化学法。结果:慢性神经源性痛时,大鼠抬腿潜伏期(痛阈值)降低,经多次电针后,随着电针次数的增加抬腿潜伏期也逐渐升高(P<0.05)。脊髓背角的NOS活性,慢性痛大鼠明显降低,电针后又明显回升(P<0.05)。结论:慢性神经源性痛时,热痛敏的行为学表现与NOS活性的下调变化相一致,而电针对慢性神经源性痛的抑制及对脊髓背角NOS活性的表达升高有一定的作用。

Effect of Electroacupuncture on Pain Behavior Responses and NOS Activity in Dorsal Horns of Spinal Cord in Rats with Chronic Pain

Objective:To observe changes of nitric oxide synthase(NOS) activity and neuropathic pain responses and the effect of electroacupuncture(EA) of "Huantiao"(GB 30)-"Yanglingquan"(GB 34) on NOS activity in rats with chronic constriction injury(CCI) of sciatic nerve.Methods:Seventy-two SD rats were evenly randomized into control,model and EA groups.CCI model was established by wrapping the sciatic nerve(4-5 mm proximal to the furcated site) with a thin polyethylene cannula((2-3) mm long) according to Mosconi's method.Electroacupuncture(4-16 Hz,1-3 V,intermittent dense-sparse waves) was given to "Huantiao"(GB 30) and "Yanglingquan"(GB 34) for 30 min,once every other day and beginning from the 2~(nd) day on after operation.The pain threshold(hind-paw withdrawal latency) was measured by giving plantar radiation thermal stimulation at different time(2 d,4 d,7 d,14 d,28 d after establishing model).NOS activity of tissues of the lumbar spinal cord was detected by using histochemical method(NADPH-d).Results:Compared with pre-operation,the paw withdrawal latency(PWL) reduced significantly in all the 3 groups(P<0.05,0.01) after operation and recovered 7 days and 14 days later in control and EA groups respectively.The PWL values of model group were significantly shorter than those of control group from the 2~(nd) day to the 28~(th) day after operation(P<0.05,0.01).Compared with model group,PWL values of EA group from the 4~(th) day to 28~(th) day after operation were significantly higher(P<0.05,0.01),suggesting that EA could evidently raise pain threshold to relieve pain.The optical density(OD) values of NOS of the spinal dorsal horn in model group were significantly lower than those in control group from the 4~(th) day to 28~(th) day after operation(P<0.05,0.01).Compared with model group,OD values of NOS in EA group were significantly higher from the 4~(th) day to 28~(th) day after operation(P<0.05,0.01),suggesting that EA could raise NOS activity in CCI rats.Conclusion:EA of "Huantiao"(GB 30) and "Yanglingquan"(GB 34) can effectively inhibit chronic neuropathic pain and upregulate the expression of NOS in the spinal dorsal horn of CCI rats.