大鼠三叉神经痛模型中小胶质细胞激活情况及经时变化

Microglia activation and temporal changes in rat model of trigeminal neuralgia

目的研究大鼠三叉神经痛模型中三叉神经脊束核尾侧亚核(Sp5C)小胶质细胞激活情况及随时间的变化,并探究其与颌面部疼痛是否具有一致性。方法部分结扎大鼠三叉神经的眶下神经(IoN)分支,引起三叉神经慢性压迫性损伤(CCI),构建大鼠三叉神经痛动物模型(IoN-CCI)。手术当天(术前)、术后第1、5、10、15、30天观察大鼠行为学变化,通过电子Von Frey测痛仪测试机械痛阈变化,称重测量体重变化,免疫组织化学染色检测Sp5C中小胶质细胞标志物钙离子结合衔接分子1(Iba-1)表达量变化,并对3种不同形态的小胶质细胞占比进行分析。结果行为学变化及机械痛阈变化显示,IoN-CCI组手术同侧颌面部疼痛水平在术后先升高后降低。IoN-CCI组手术同侧Sp5C的Iba-1表达及变形虫样小胶质细胞占比分别在术后第10天及术后第5天达到峰值,至术后第30天基本恢复至与同组对侧一致,该趋势与颌面部疼痛水平变化基本一致。结论眶下神经部分结扎构建大鼠三叉神经痛模型引起Sp5C中小胶质细胞激活,激活情况与颌面部疼痛情况基本一致,在第10天达到最高峰。

Objective This study aimed to investigate whether the microglia in the spinal trigeminal nucleus caudal part(Sp5C)were activated in a rat model of trigeminal neuralgia and to explore whether the activation level of microglia is consistent with maxillofacial pain level.Methods Chronic constriction injury of trigeminal nerve(CCI)was induced by partial ligation of infraorbital nerve(IoN)in rats.The behavioral change of rats observed at D1,D5,D10,D15,and D30 days post-surgery and the change of pain threshold were detected with electronic Von Frey filaments served as an evaluation index of maxillofacial pain.Weight change was measured by weighing.Ionized calcium binding adaptor molecule-1(Iba-1)expression level of Sp5C at each time point was detected,and three microglia morphological categories were analyzed by immunohistochemical staining.Results The changes of behavioral and pain threshold suggested the maxillofacial pain level first increased and then decreased post-surgery in the IoN-CCI group.Both the expressions of Iba-1 and proportion of ameboid morphology in ipsilateral Sp5C increased from D1 and reached their peaks in D10 and D5,respectively.Then,they recovered nearly to the same level with contralateral Sp5C on D30.This trend was consistent with the maxillofacial change.Conclusion The model of trigeminal neuralgia in rats constructed by partial ligation of infraorbital nerve can induce the activation of microglia in Sp5C,and the activation level is consistent with maxillofacial pain,which reached its peak at around D10 post-surgery.