电针降低神经病理性疼痛大鼠脊髓白细胞介素-6的表达

目的:观察电针对神经病理性疼痛大鼠脊髓白细胞介素-6(IL-6)蛋白表达以及痛敏状态的影响,探讨电针治疗神经病理性疼痛的可能机制。方法:雄性SD大鼠24只,分为假手术组、手术组和电针治疗组。采用大鼠坐骨神经慢性压迫性损伤(CCI)模型,电针“委中”与“环跳”穴,观察其对大鼠机械性痛阈和热痛阈的影响,并应用免疫组化技术观察大鼠脊髓IL-6的变化。结果:假手术组大鼠脊髓IL-6免疫阳性细胞平均光密度值为0.1361±0.0113,CCI手术可以显著降低大鼠痛阈,并且大鼠手术侧脊髓IL-6免疫阳性细胞平均光密度值增加(0.5152±0.0372),而电针治疗后则明显抑制大鼠脊髓IL-6蛋白(0.3527±0.0379)的表达,并显著减轻CCI大鼠的痛敏状态。结论:电针治疗神经病理性疼痛可能与下调脊髓IL-6的表达有关。

Electroacupuncture Downregulates the Expression of Spinal Interleukin-6 Protein in Chronic Neuropathic Pain Rats

Objective: To investigate the effect of electroacupuncture(EA)on spinal interleukin-6(IL-6) protein expression in neuropathic pain rats.Methods: Twenty-four adult SD rats were evenly and randomly divided into sham-operation group,model group and EA group.Chronic constrictive injury(CCI) model was established by ligating the sciatic nerve with catgut under anesthesia(10% chloral hydrate,300 mg/kg).EA(2 Hz,1 mA) was applied to "Weizhong"(BL 40) and "Huantiao"(GB 30) for 30 min,once on the 1~st,4~th and 7~th day after operation separately.The mechanical(von Frey filaments) and thermal(heat radiation) pain thresholds were measured before operation and on the 7~th day after the operation.The expression of IL-6 in the spinal cord(L_4-5) tissues was assayed by immunohistochemical technique.Results: Before operation,no significant differences were found among the 3 groups in both mechanical pain threshold and thermal pain threshold of the bilateral hind-limbs(P>0.05).In comparison with sham-operation group,after CCI,both the mechanical and thermal pain thresholds of model group on the affected hind-limb lowered significantly,appearing mechanical allodynia and thermal hyperalgesia.Compared with model group,the mechanical and thermal pain thresholds of EA group increased significantly after EA(P<0.05).Correspondingly,the average optical density value of IL-6 immunoreactive(IR) positive cells in the ipsilateral spinal dorsal horn of model group was significantly higher than that of sham-operation group and EA group(P<0.05).It indicated that EA could markedly suppress CCI-induced allodynia and hyperalgesia and increase of IL-6 expression in the spinal cord.Conclusion: EA analgesia may be related to its resultant downregulation of IL-6 expression in the dorsal horn of the spinal cord in neuropathic pain rats.