神经病理性疼痛中代谢型谷氨酸受体5型的表达变化

Expression Changes of Metabotropic Glutamate Receptor 5 in Neuropathic Pain

目的研究神经病理性疼痛形成过程中脊髓背角和背根神经节(DRG)代谢型谷氨酸受体5型(mGluR5)表达的改变。方法雄性SD大鼠84只随机分为7组(n=12)Con组为空白对照组;S3、S7、S14组分别为假手术后3、7、14d测痛阈取标本;C3、C7、C14组分别为慢性坐骨神经紧缩性神经病理性疼痛(CCI)模型术后3、7、14d测痛阈取标本。术后3、7、14d分别用VonFrey细丝测量机械性痛阈后处死大鼠,取腰膨大脊髓背角和DRG的标本,用RT-PCR和免疫蛋白印迹方法从转录和翻译水平研究mGluR5的表达变化。结果CCI手术组的术后痛阈均显著低于Con组和同时间段的假手术组(P<0.05)。CCI术后3d脊髓背角水平mGluR5的mRNA和蛋白质表达显著高于假手术3d组和Con组(P<0.05),而术后7和14d时CCI组与假手术组和空白对照组比较差异无显著性(P>0.05)。在DRG水平,mGluR5的表达差异均无显著性(P>0.05)。结论脊髓水平的mGluR5在CCI神经病理性疼痛模型早期表达明显升高,提示参与神经病理性疼痛的形成。

Objective To investigate the expression changes of metabotropic glutamate receptor 5 （mGluR5） in neuropathic pain. Methods Eighty-four adult male Sprague Dawley rats weighing 180-220 g were randomly derided into 7 groups （n = 12 ） ： control group; S3, S7, and S14 groups： rats received the sham operation, the mechanical pain threshold was measured, and then the rats were decapitated and the ipsilateral lumbar spinal cord dorsal horn and dorsal root ganglion （DRG） samples were obtained on the 3rd, 7th, 14th postoperative day, respectively; C3, C7, and C14 groups： the chronic sciatic nerve constriction （CCI） model was established, the mechanical pain threshold was measured and the samples were obtained on the 3 rd, 7th, 14th postoperative day, respectively. The expression level of mGluR5 mRNA and protein in the spinal cord and DRG were measured using the reverse transcriptase polymerase chain reaction and Western blot. Results In the CCI group, the mechanical pain threshold in each observation day was significantly lower than in the sham operation group （ P 〈 0. 05 ）. In the spinal cord, the expressions of mGluR5 mRNA and protein were significantly elevated in the C3 group than in the S3 and the control group （ P 〈 0. 05 ）. On the 7th and the 14th postoperative day, no significant difference was found in the expression of mGluR5 mRNA and protein between CCI groups and the sham operation groups or the control group. No change was detected in DRG mRNA or protein. Conclusion mGluR5 is differentially expressed in spinal cord in response to neuropathic pain, which suggests that mGluR5 may be involved in the mechanism of neuropathic pain.