神经病理性疼痛大鼠脊髓背角小胶质细胞P2X4受体的表达及意义

Expression and Its Significance of P2X4 Receptor in Microglia from Spinal Dorsal Horn of Rats with Neuropathic Pain

目的探讨神经病理性疼痛大鼠脊髓背角小胶质细胞离子型嘌呤受体(ionotropic purinoceptor,P2X)P2X4的表达及其意义。方法雌性SD大鼠20只,随机分为坐骨神经保留性损伤(SNI)组和对照组。SNI组大鼠于左后肢制备SNI模型,对照组大鼠仅暴露坐骨神经后立即缝合手术切口。术后观测机械疼痛阈值的变化,于术后第7天断头处死大鼠,截取L4～6段脊髓,分离左右侧脊髓。采用免疫组化法检测脊髓背角P2X4受体及蛋白激酶p38MAPK的表达。结果与对照组相比,SNI模型组大鼠机械刺激50%缩爪阈值显著降低(P<0.01)。SNI模型组大鼠手术侧脊髓背角活化的小胶质细胞表面P2X4受体的表达水平(456.86±32.21)较非手术侧(106.27±12.16)明显增高(P<0.01),同时SNI模型组大鼠手术侧脊髓背角p38MAPK表达水平(399.95±32.42)较非手术侧(123.63±15.47)明显增高(P<0.01)。结论神经病理性疼痛大鼠模型脊髓背角活化小胶质细胞P2X4受体表达增加,可能通过激活p38MAPK促进了疼痛的发生。

Objective To investigate the expression and its significance of P2X4 receptor in microglia from spinal dorsal horn of rats with neuropathic pain.Methods Twenty female SD rats were randomly divided into SNI group and control group with 10 rats each.The rats in control group were subjected to a sham operation only on the left hind limb,and those in SNI group to a partial lesion on the left sciatic nerve.After surgery the change of pain threshold from machinery pain was observed until neuropathic pain developed seven days after operation.All rats were killed by cervical dislocation.L4-6 spinal cord segments were taken after the left and right spinal cords were separated.P2X4 receptor and p38MAPK expression in spinal dorsal horn was detected by immunohistochemistry.Results As compared with the control group,50% paw withdrawal threshold was decreased significantly in the SNI group（P〈0.01）.The level of P2X4 receptor expression（absorbance value：456.86±32.21）in activated microglias from the spinal dorsal horn and the activity of p38MAPK（absorbance value：399.95±32.42）on the operative side in SNI group were increased more significantly than those（absorbance value：106.27±12.16）on the operative side in control group and（absorbance value：123.63±15.47）on the non-operative side in SNI group（P〈0.01）.Conclusion In the spinal cord of rats with neuropathic pain,up-regulation of P2X4 receptor in activated microglias from spinal dorsal horn might promote the development of chronic neuropathic pain by activating p38MAPK.