坐骨神经脉冲射频对慢性坐骨神经压迫损伤模型大鼠脊髓背角胶质细胞活化水平的影响及其镇痛作用

目的：观察坐骨神经结扎处脉冲射频（PRF）对慢性坐骨神经压迫损伤（CCI）模型大鼠脊髓背角小胶质细胞和星形胶质细胞活化水平的影响，探讨坐骨神经PRF镇痛机制与脊髓背角小胶质细胞和星形胶质细胞活化水平的关系。方法：雄性SPF级SD大鼠40只随机分为CCI假造模PRF假治疗组（SS组）、CCI假造模PRF治疗组（SP组）、CCI造模PRF假治疗组（CS组）和CCI造模PRF治疗组（CP组），每组10只。CCI造模成功后4 d行PRF治疗，在坐骨神经结扎处行标准PRF （120s、42℃）。于CCI造模前1d （D₀）及造模后1、3、5和7 d （D₁、D₃、D₅和D₇）测定大鼠患侧机械缩足反射阈（MWT）和热缩足反射潜伏期（TWL）。疼痛行为学测试完成后（D₇）取患侧L3~5脊髓背角，Western blotting法检测脊髓背角小胶质细胞特异性蛋白（Iba-1）和胶质原纤维酸性蛋白（GFAP）的蛋白表达水平。结果：与SS组比较，CCI造模后不同时间点CS组大鼠患侧出现足外翻、跛行、脚趾弯曲聚拢和行走时抬足等行为学表现，MWT和TWL均明显下降（P<0.01），脊髓背角Iba-1和GFAP蛋白表达水平明显升高（P<0.05）；与CS组比较，CP组大鼠（D₅和D₇） PRF后足外翻、跛行、脚趾弯曲聚拢和行走时抬足等行为学变化明显缓解，MWT和TWL值明显升高（P<0.01），脊髓背角Iba-1蛋白表达水平明显下调（P<0.05），GFAP蛋白表达水平差异无统计学意义（P>0.05）。结论：坐骨神经PRF能有效缓解CCI模型大鼠的神经病理性疼痛（NP），坐骨神经PRF可抑制脊髓背角小胶质细胞活化水平，其镇痛机制可能与抑制脊髓背角小胶质细胞活化有关。

Effect of sciatic nerve pulsed radiofrequency glial activation levels in spinal dorsal horn in chronic constriction injury rat models and its analgesia effect

Objective: To observe the effect of sciatic nerve pulsed radiofrequency(PRF) on the activation levels of microglia cells and astrocytes in spinal dorsal horn in the chronic constriction injury(CCI) rat models, and to explore the relationships between the analgesic mechanism of sciatic nerve PRF and the activation levels of microglia cells and astrocytes in the spinal dorsal horn.Methods: Forty male SD rats were randomly divided into CCI sham-operation+RPF sham group(SS group), CCI sham-operation+RPF group(SP group), CCI+RPF sham group(CS group), CCI+RPF group(CP group)(n=10). PRF was applied on the sciatic nerve on the 4th day after CCI operation for 120 s, with a maximum temperature of 42℃.The mechanical withdrawal thresholds (MWT) and thermal paw withdrawal latencies (TWL) were measured to evaluate mechanical hyperalgesia and thermal hyperalgesia 1 d before operation (D₀) and 1,3,5,7 d after operation (D₁, D₃, D₅, D₇). Western blotting method was used to detect the protein expression levels of ionized calcium binding adapter molecule 1(Iba-1) and glial fibrillary acidic protein (GFAP) in the ipsilateral spinal dorsal horn of L3-5 after pain behavioral test(D₇).Results: Compared with SS group, the rats in CS group after CCI had the significant behavioral changes, such as hallux valgus, lameness, toe bending, and foot raising during walking; MWT and TWL were decreased significantly(P<0.01); the expression levels of Iba-1 and GFAP proteins in the ipsilateral spinal dorsal horn were increased significantly(P<0.05). Compared with CS group, the behavioral changes of the rats in CP group (D₅, D₇) such as hallux valgus, lameness, toe bending, and foot raising during walking were alleviated significantly; MWT and TWL were increased significantly(P<0.01); the Iba-1 protein expression level in spinal dorsal horn was down-regulated significantly (P<0.05) and the GFAP protein expression level did not change significantly (P>0.05).Conclusion: PRF on sciatic nerve can relieve the neuropathic pain (NP) of the CCI rat models; PRF on sciatic nerve can inhibit activation of the microglia cells in the spinal dorsal horn. The analgesic mechanism of PRF on sciatic nerve may be associated with the inhibition of the activation of microglia cells in the spinal dorsal horn.