基底外侧杏仁核小胶质细胞参与单关节炎小鼠痛觉敏化和痛相关厌恶行为

Contribution of microglia in the basolateral amygdala to pain hypersensitivity and pain-related aversion in mouse model of monoarthritis

目的研究基底外侧杏仁核(basolateral amygdala,BLA)小胶质细胞对小鼠膝关节单关节炎诱导的痛觉敏化与痛相关负性情绪的影响。方法61只小鼠用于行为学测试(对照组14只,模型组47只),6只小鼠用于形态学实验(对照组与模型组各3只)。通过向小鼠膝关节腔注射完全弗氏佐剂(complete Freund’s adjuvant,CFA)建立膝关节单关节炎动物模型。采用von Frey test和Hargreaves test分别测试小鼠的机械痛阈和热痛阈,用于评估小鼠的痛觉敏化。采用条件位置回避装置检测小鼠的痛相关厌恶行为,采用旷场和高架十字迷宫测试小鼠痛相关焦虑样行为。通过免疫荧光染色与Imaris软件对BLA脑区小胶质细胞进行3D重构,进而评估CFA造模后BLA脑区小胶质细胞的形态学变化。结果与对照组相比,CFA造模后小鼠术侧产生显著的机械触诱发痛与热痛觉敏化,并至少持续12和19天。CFA造模能够引起小鼠产生痛相关厌恶行为和焦虑样行为,并伴随BLA小胶质细胞的显著激活。抑制BLA小胶质细胞激活能够缓解CFA造模引起的痛觉敏化和痛相关厌恶行为,但对焦虑样行为无显著影响。结论小鼠膝关节注射CFA能够引发痛觉敏化、痛相关厌恶行为以及焦虑样行为,其中痛觉敏化和痛相关厌恶行为可能与BLA脑区小胶质细胞的激活相关。

Objective To investigate the contribution of microglia in the basolateral amygdala(BLA)to pain hypersensitivity and pain-related aversion in knee-joint monoarthritis mice.Methods A total of 61 mice were used for behavioral tests(14 mice in the control group and 47 mice in the model group),and other 6 mice were used for cell morphology(3 mice in each group).An animal model of knee-joint monoarthritis was established by injection of complete Freund’s adjuvant(CFA)into the knee-joint cavity of mice.The von Frey and Hargreaves tests were used to examine mechanical allodynia and thermal hyperalgesia in mice,respectively.The place escape/avoidance paradigm test was used to examine pain-related aversion.Open field test and elevated plus maze test were used to examine anxiety-like behaviors in mice.Morphological changes of microglia in the BLA area after CFA injection were assessed by 3D reconstruction of microglia in the BLA brain region using immunofluorescence staining and Imaris software.Results Compared with the control group,CFA-arthritic mice produced significant mechanical and thermal hyperalgesia in the ipsilateral hindpaw and maintained for at least 12 and 19 days,respectively.Meanwhile,CFA injection induced pain-related aversion and anxiety-like behaviors in mice,accompanied by significant activation of BLA microglia.Inhibition of BLA microglia activation alleviated CFA-induced hyperalgesia and aversive behaviors but had no significant effects on anxiety-like behaviors.Conclusion CFA-arthritic mice produce hyperalgesia,pain-related aversion,and anxious behavior,in which hyperalgesia and pain-related aversion may be mediated by the activation of microglia in BLA.