背根神经节巨噬细胞迁移抑制因子参与 调控神经病理性疼痛的机制研究

Role of migration inhibitory factor in rat model of dorsal root ganglion mediated neuropathic pain

摘要:

目的 探讨脊髓背根神经节（DRG）巨噬细胞迁移抑制因子（MIF）对神经病理性疼痛的作用及可 能的调控机制。方法 成年雄性SD 大鼠随机分为3 组（n =8）：假手术组（Sham 组）、坐骨神经结扎（CCI）模 型对照组（以下简称CCI 组）、ISO-1 组（CCI+ 鞘内注射ISO-1）。鞘内置管5 d 后予以左侧坐骨神经结扎。 CCI 组和ISO-1 组连续14 d 鞘内注射10% DMSO 10 μl 或含ISO-1 30 μg 的DMSO 10 μl，每天1 次。在术前1 天， 术后第1、3、5、7、10 及14 天（给药2 h 后）测定机械痛阈值；在第7 和14 天取大鼠DRG，ELISA 检测肿瘤 坏死因子α（TNF-α）、白细胞介素1β（IL-1β）的表达变化，Western blot 检测MIF 表达变化，并于第14 天记 录受损坐骨神经传导速度（CV）。结果 与Sham 组比较，术后CCI 组机械痛阈值均降低（P <0.05）；与CCI 组比较， ISO-1 组术后第10 和14 天机械缩足反射阈值均升高（P <0.05）。与Sham 组比较，CCI 组第7 和14 天背根神经 节MIF、TNF-α、IL-1β 表达上调（P <0.05）；与CCI 组比较，ISO-1 组第7 和14 天MIF、TNF-α、IL-1β 表达下调（P <0.05）。神经电生理的结果显示，与Sham 组比较，CCI 大鼠坐骨神经的CV 降低，差异有统计学意 义（P <0.05）；ISO-1 组与CCI 组大鼠坐骨神经的CV 比较，差异无统计学意义（P >0.05）。结论 鞘内注射MIF 拮抗剂ISO-1 可以减轻大鼠机械痛敏，下调DRG MIF、TNF-α 和IL-1β 表达，但不能修复受损坐骨神经。 MIF 拮抗剂ISO-1 可能通过抑制脊髓背根神经节炎症反应，减轻大鼠神经病理性疼痛。

Abstract:

Objective To investigate the role of macrophage migration inhibitory factor (MIF) in dorsal root ganglion (DRG) mediated neuropathic pain. Methods Animals in all groups were intrathecally catheterized 5 days before surgery. SD rats were randomized into three groups (n = 8): sham group in which rats received all surgical procedure except nerve ligation, CCI group in which rats received CCI and intrathecal injection of 10% DMSO (10 μl per day for 2 weeks), and ISO-1 group in which rates received CCI and intrathecal injection of ISO-1 (30 ug/ul per day for 2 weeks). Mechanical allodynia of the plantar surface of the left hind-paw was tested on 1st d before surgery, 1st d, 3rd d, 5th d, 7th d, 10th d, and 14th d after surgery in all rats (2h after intrathecal injection). The expressions of MIF, TNF-α and IL-1β in DRG were examined by western blot or ELISA on the 7th and 14th day after surgery. The Conduction Velocity (CV) of sciatic nerve was tested on the 14th day after surgery. Results Paw mechanical withdrawal threshold (PMWT) in CCI group was significantly lowered compared with sham group (P < 0.05), which was abolished by treatment of ISO-1 on 5th d, 7th d, 10th d, and 14th d after surgery (P < 0.05). Westernblot and ELISA showed that the expression of MIF, TNF-α, and IL-1β in CCI group was markedly increased in the ipsilateral DRG on the 7th and 14th day after nerve injury when compared with sham group (P < 0.05), which was significantly suppressed by ISO-1 admission (P < 0.01). Electrophysiology test showed that CV was decreased greatly in the CCI group compared with that in sham group while no difference was observed between CCI and ISO-1 groups. Conclusions MIF antagonist ISO-1attenuates tactile allodynia without obvious physical recovery of sciatic nerve through attenuating local inflammation, suggesting that blockage of MIF might be a therapeutic strategy for treating neuropathic pain.