Elucidation of the pain mechanisms in the extra-foraminal and double crush lesions of the L5 spinal nerve

L5脊神经背根神经节(DRG)在背根神经节近端2 mm或远端2 mm处结扎，用6.0真丝结扎两个部位，制成大鼠腰神经根病模型。术后7天用机械敏感性、免疫组织化学和活体膜片钳记录检测神经根病变的程度。在行为学研究中，损伤背根节的大鼠最敏感，损伤背根节远端的大鼠比损伤背根节近端的大鼠更敏感。L5节段I-II层激活的小胶质细胞数和EPSC的波幅和频率与行为学研究的顺序一致。二次挤压模型与背根节损伤模型比较，差异无统计学意义。此外，我们还发现腰交感神经切除降低了DRG损伤模型的机械敏感度和EPSC频率。

The lumbar radiculopathy rat model was created by ligating the dorsal root ganglia (DRG) of the L5 spinal nerve, 2 mm proximal to the DRG or 2 mm distal to the DRG, and the two sites of them (i.e. double crush) with 6.0 silk. We examined the degree of the radiculopathy using mechanical sensitivity, immunohistochemistry and in vivo patch-clamp recordings, 7 days after surgery. The rats injured the DRG was most sensitive, and the rats injured distal to the DRG were more sensitive than those rats injured proximal to the DRG in the behavioral study. The number of activated microglia in laminas I-II of the L5 segmental level and the amplitudes and frequencies of EPSC in the rats increased in the same order with the behavioral study. There was no significant difference between the double crush models and the DRG injured model. Moreover, we found that lumbar sympathectomy decreased the mechanical sensitivity and the frequencies of EPSC in the DRG injured model.