大鼠咬合干扰致口颌面痛敏的自我赏罚实验行为学特点

Characteristics of orofacial operant test for orofacial pain sensitivity caused by occlusal interference in rats

目的:测定咬合干扰模型(experimental occlusal interference,EOI)与部分眶下神经切断模型(partial infraorbital nerve transection,pIONX)两种口颌面疼痛模型大鼠的自我赏罚实验行为学表现及机械诱发反应痛敏,比较两种测痛方法所反映的不同疼痛模型的疼痛特点。方法:Sprague-Dawley大鼠随机分为8组,每组6只,分别为机械刺激诱发反应组(sham-EOI、EOI、sham-pIONX与pIONX组,sham为假手术组)与自我赏罚实验组(sham-EOI、EOI、sham-pIONX与pIONX组,sham为假手术组)。于建模前及建模后1、3、7、10、14、21 d测定各组大鼠机械刺激反应阈值与自我赏罚行为学表现。结果:机械刺激诱发反应组大鼠pIONX组von Frey纤维的机械刺激反应阈值于1~21 d出现显著下降(P<0.05),7~10 d达到最低;自我赏罚实验组大鼠pIONX组的总摄食时间于10~21 d出现显著下降(P<0.05),10~14 d达到最低。机械刺激诱发反应组大鼠EOI组von Frey纤维的机械刺激反应阈值于3~21 d出现显著下降(P<0.05),7 d达到最低;自我赏罚实验组大鼠EOI组的总摄食时间于1~21 d出现显著下降(P<0.05),7~10 d达到最低。结论:自我赏罚实验可以作为口颌面疼痛的行为学测定新方法,而且在神经病理性疼痛和咬合干扰所致口颌面疼痛的模型中均可稳定应用。两种模型中,自我赏罚实验与机械刺激诱发反应均表现出了不同的痛敏时程,两种方法互为补充可以更全面地揭示不同模型的疼痛行为学特点。

Objective:To compare the orofacial pain sensitivity with operant test and mechanical hyperalgesia with von Frey filaments of two orofacial pain models(EOI:experimental occlusal interference;pIONX:partial infraorbital nerve transection).To investigate the operant and evoked characteristics of EOI-rats.Methods:The orofacial operant behaviors were tested by Ugo Basile Orofacial Stimulation Test System.The mechanical thresholds of vibrissal pads were tested by von Frey filaments.Male Sprague-Dawley rats were randomly divided into eight groups:von Frey group:sham-EOI,EOI,sham-pIONX,pIONX(sham:sham-operated group);operant test group:sham-EOI,EOI,sham-pIONX,pIONX(sham:sham-operated group).The mechanical thresholds and orofacial operant behaviors were tested on pre-operation and post-operation days l,3,7,10,14 and 21.Results:In pIONX of von Frey group,the mechanical withdrawal threshold decreased from days 1 to 21(P<0.05),peaking from days 7 to 10,and lasted until the end of the experiment.There was no significant difference between the bilateral sides.In pIONX of operant test group,the total contact time decreased from days 10 to 21(P<0.05),peaking from days 10 to 14,and lasted until the end of the experiment.In EOI of von Frey group,the mechanical withdrawal threshold decreased from days 3 to 21(P<0.05),peaking on day 7,and lasted until the end of the experiment.There was no significant difference between the bilateral sides.In EOI of operant test group,the total contact time decreased from days 1 to 21(P<0.05),peaking from days 7 to 10,and lasting until the end of experiment.Conclusion:Orofacial operant test is a stable method to evaluate orofacial pain behaviors,which could discriminate the feature of neuropathic and EOI orofacial pain.In these two animal models,both of the operant behaviors and the mechanical hyperalgesia exhibited different time courses.Orofacial operant test provides a novel method for evaluating the orofacial pain sensitivity and studying the orofacial pain mechanism thoroughly.