大鼠三叉神经痛模型中痛阈及胶质细胞源性神经营养因子的变化

Changes in pain threshold and glial cell line-derived neurotrophic factor in rat model of trigeminal neuralgia

目的研究SD大鼠三叉神经痛模型对机械刺激的痛阈和胶质细胞源性神经营养因子（GDNF）的变化。方法建立大鼠三叉神经痛样动物模型,选取SD大鼠36只,随机分为手术组、假手术组和空白对照组。手术组经口内切口行右侧三叉神经的眶下神经结扎术,假手术组只分离暴露右侧眶下神经不予以结扎,空白对照组未接受手术干预。记录大鼠术前及术后的痛阈,并在不同时间点解剖三叉神经节,通过免疫组织化学方法观察GDNF的变化。结果手术组于术后2周出现痛觉超敏反应,一直持续到术后6周才逐渐恢复,术后10～12周才恢复到术前水平。手术组大鼠术后三叉神经节中GDNF的表达量增高,且表达量随着时间的推移而改变。结论大鼠眶下神经的慢性压迫性损伤（CCI-ION）可建立三叉神经痛样的动物模型。GDNF可能通过促进神经纤维的修复再生方式参与调控三叉神经痛。

Objective This research aims to study the changes in pain threshold and glial cell line-derived neurotrophic factor （GDNF） in a Sprague Dawley （SD） rat model of trigeminal neuralgia. Methods A total of 36 male SD rats were ran- domly divided into three groups： operative, sham-operative, and control. In the operative group, a chronic constriction injury （CCI） was caused by placing loose chromic gut ligatures around the right infraorbital nerve （ION）. In the sham-operative group, the right ION was subjected to the same procedure, but without ligation. In the control group, the right ION was not subjected to any treatment. The pain thresholds of the three groups were recorded at different times after the operation. The GDNF expression in each group was analyzed via immunohistochemical staining. Results An allodynia to mechanical sti- mulation in the region of the ligated ION was observed starting on the 2nd week after operation. Pain thresholds started to increase gradually from the 6th week and returned to the original level at the 10th to 12th week after operation. Cells that ex- pressed the GDNF markedly increased in number in the operative group with changes observed at different times. Conclusion We use chronic constriction injury to the infraorbital nerve （CCI-ION） to establish a trigeminal neuralgia-like animal model in SD rats. GDNF may play a role in regulating pain by promoting the restoration and regeneration of nerve fibers.