电针对神经病理性疼痛大鼠痛觉过敏及脊髓背角钾-氯离子协同转运体2表达的影响

关键词：针刺  神经病理性疼痛  脊髓背角  钾-氯离子协同转运体2

Keywords:acupuncture  neuropathic pain  spinal cord dorsal horn  KCC2

摘要：

      摘要 目的：观察患侧电针和健侧电针足三里穴、阳陵泉穴对神经病理性疼痛大鼠行为学表现以及脊髓背角钾-氯离子协同转运体2（KCC2）表达的影响，探讨患侧选穴和健侧选穴两种针刺方案的镇痛效应，以及KCC2在电针镇痛效应中的作用。 方法：将40只雄性SD大鼠随机分为4组：假模组、模型组、患侧电针组、健侧电针组，每组10只。建立大鼠坐骨神经慢性压迫性损伤（CCI）模型，治疗组于术后1周开始电针治疗，每天1次，连续7天。各组于术前（0天）及术后3、5、7、10、12、14天分别测量大鼠患侧足机械足反射阈值（MWT）和热缩足反射潜伏期（TWL）。术后14天处死大鼠，取脊髓组织行HE染色观察组织病理学改变，并采用免疫组化方法检测脊髓背角KCC2蛋白的表达。 结果：与术前比较，CCI各组大鼠痛阈明显降低，出现痛觉过敏（P<0.001），电针治疗后大鼠MWT和TWL均有不同程度的持续升高，且患侧与健侧电针相比无明显差异。HE染色结果提示，患侧电针组与健侧电针组脊髓背角组织及神经元病变程度较模型组减轻。术后14天患侧与健侧电针组较模型组脊髓背角患侧KCC2表达显著增加（P<0.05），并且患侧电针组与健侧电针组无明显差异。 结论：患侧电针和健侧电针能产生类似的镇痛效果，均可减轻外周神经损伤后引起的痛觉过敏。患侧电针与健侧电针治疗均可抑制KCC2蛋白的表达下调，电针的镇痛作用可能是通过增加脊髓背角中KCC2的表达实现的。

Abstract:

      Abstract Objective: To investigate the effect of electro-acupuncture (EA) on the behaviors and the expression of KCC2 in spinal cord dorsal horn by applying Zusanli acupoint (ST-36) and Yanglingquan acupoint (GB-34) in chronic constriction injury (CCI) rats. Method: Forty male SD rats were randomly divided into 4 groups: sham CCI group, CCI group, ipsilateral EA group and contralateral EA group, with 10 cases in each group. EA groups received EA treatment for 7 days. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were tested on the day before operation and at 3,5,7,10,12,14 days after CCI operation. In addition, the pathological changes of spinal cord dorsal horn were observed by HE stain and the expression of KCC2 was detected by immunohistochemistry. Result: The MWT and TWL values were decreased after CCI operation when compared with pre-operation(P<0.001). After EA treatment for 7 days, the MWT and TWL values for two EA groups were markedly increased (P<0.05). EA treatment significantly attenuated pathological changes of spinal cord dorsal horn. Furthermore, compared with the CCI group, the KCC2 expression was upregulated in the ipsilateral EA group and contralateral EA group after EA treatment(P<0.05), and there was no significant difference between the ipsilateral EA group and contralateral EA group. Conclusion: EA could reduce CCI-induced hyperalgesia. The analgesic effect of EA may be achieved by inhibiting the expression of KCC2 in spinal cord dorsal horn.