代谢型谷氨酸受体5拮抗剂(MPEP)在大鼠颞下颌关节疼痛中的作用和可能机制

目的探讨应用代谢型谷氨酸受体5拮抗剂(MPEP)后,福尔马林致颞下颌关节疼痛大鼠三叉神经节内降钙素基因相关肽(CGRP)的表达变化,为临床颞下颌关节疼痛治疗提供实验依据。方法 SD大鼠36只,随机均分为4组,正常对照组(不做任何处理),阴性对照组(右侧颞下颌关节内注射50μl生理盐水),甲醛组(右侧颞下颌关节内注射50μl5%formalin),MPEP(2-甲基-6苯基乙炔嘧啶)组[25μlMPEP(5mmol/L)+50μl5%formalin]。将5%甲醛注入右侧颞下颌关节腔内,诱导大鼠颞下颌关节疼痛。计数各组大鼠60min内伤害性行为反应(包括刮擦头面部及缩头)。并利用免疫组织化学方法检测三叉神经节内CGRP的蛋白定位与表达。结果甲醛组大鼠搔刮头面部及缩头反应持续时间明显高于正常对照组及阴性对照组(P<0.05),MPEP组搔刮头面部及缩头等伤害性行为反应明显低于甲醛组(P<0.05)。免疫组化结果显示甲醛组、MPEP组三叉神经节内CGRP免疫反应阳性物质与正常对照组比较显著增加(P<0.05),生理盐水组与正常组比较无统计学差异(P>0.05),MPEP组与甲醛组比较CGRP免疫反应阳性物质明显降低(P<0.05)。结论代谢型谷氨酸受体5拮抗剂减轻福尔马林引起的大鼠颞下颌关节疼痛可能与其下调三叉神经节内CGRP的表达水平相关。

The effect of mGluR5 antagonist on temporomandibular joint pain induced by formalin in SD rats

Objective To study the expression change of calcitonin gene related peptide(CGRP) in the trigeminal ganglion to explore the effect and possible mechanism of mGluR5 antagonist (MPEP) on temporomandibular joint pain induced by formalin in rats. Methods A total of 36 adult SD rats were randomly divided into 4 groups (n=9): normal control group (no-treated), negative control group (Nacl 0.9% injection), formalin group (5%formalin injection), MPEP group(5%formalin+5mmol/L MPEP injection). Immunohistochemistry was used to detect the expression of CGRP in trigeminal ganglion. Results The behaviors time of flinching the head and rubbing the orofacial region was longer in formalin group than in control group (P<0.05), but shorter in MPEP group than in formalin group. The expression levels of CGRP were higher in formalin group than in normal group (P<0.05), but lower in MPEP group than in formalin group with no significant difference between normal and negative control groups (P>0.05). Conclusion The alleviated formalin-induced temporomandibular joint pain by MPEP might be related to the downregulation of CGRP in trigeminal ganglion.