多巴胺3型受体敲除对电击诱发恐惧记忆形成和唤起的抑制作用  

Dopamine receptor 3 knockout inhibits acquisition and recall of fear memory induced by electric shocks

作　　者：丁晓燕[1,2] 王志媛 吴宁 李锦 宋睿 DING Xiaoyan;WANG Zhiyuan;WU Ning;LI Jin;SONG Rui(Nanjing University of Chinese Medicine,Nanjing 210000,China;Beijing Key Laboratory of Neuropsychopharmacology,State Key Laboratory of National Security Specially Needed Medicines,Academy of Military Sciences,Beijing 100850,China)

机构地区：[1]南京中医药大学,江苏南京210000 [2]军事医学研究院国家安全特需药品全国重点实验室,神经精神药理学北京市重点实验室,北京100850

出　　处：《中国药理学与毒理学杂志》2025年第2期81-88,共8页Chinese Journal of Pharmacology and Toxicology

基　　金：北京市自然科学基金(7212159)。

摘　　要：目的研究多巴胺3型受体(D_(3)R)对强烈电击诱发恐惧记忆的影响及其可能的神经生物学机制。方法(1)以野生型(WT)和D_(3)R敲除(D_(3)R^(-/-))小鼠为研究对象,用足底热辐射法以缩足反应潜伏期(PWL)为观察指标评价WT和D_(3)R^(-/-)小鼠足底基础痛阈值,以排除痛阈值差别对强烈电击效果的影响。(2)将WT和D_(3)R^(-/-)小鼠分别分为对照组和模型组,第1天模型组施予不可逃避性足底电击(1.5 mA,持续10 s,间隔10 s,共15次),对照组不施予电击。于第2,7,10,14和16天进行情景恐惧测试,通过计算僵住时间(FT)百分率反映环境线索诱发的恐惧记忆形成;于环境线索诱发的恐惧反应消退后(第17天)再次给予模型组低强度电流(0.5 mA,持续10 s,间隔10 s,共15次)刺激进行恐惧记忆唤起,对照组不施予电击,第18天进行情景恐惧测试,通过观察FT百分率反映环境线索诱发的恐惧记忆唤起。(3)另一批WT和D_(3)R^(-/-)小鼠,分组和处理同(2),运用光纤记录技术检测电击时WT和D_(3)R^(-/-)小鼠中脑腹侧被盖区(VTA)多巴胺(DA)能神经元钙荧光信号实时动力学变化,以曲线下面积(AUC)为指标量化DA能神经元兴奋性。结果(1)与WT小鼠相比,D_(3)R^(-/-)小鼠PWL无显著变化。(2)与WT对照组相比,WT模型组在电击后第2,7,10和14天FT百分率均显著增加(P<0.05);与D_(3)R^(-/-)对照组相比,D_(3)R^(-/-)模型组仅在电击后第2和7天FT百分率显著增加(P<0.01)。与WT模型组小鼠相比,D_(3)R^(-/-)模型组小鼠在电击后第2,7,10和14天FT百分率均显著减少(P<0.05,P<0.01)。在唤起阶段(第18天),与各自对照组相比,WT模型组和D_(3)R^(-/-)模型组(P<0.05)小鼠FT百分率均显著增加(P<0.05,P<0.01),而D_(3)R^(-/-)模型组FT百分率显著低于WT模型组小鼠(P<0.01)。(3)在电击过程中,WT模型组和D_(3)R^(-/-)模型组小鼠VTA中DA能神经元钙信号在电击前2 s内均迅速升高,在电击2~10 s时间段内钙信号均缓慢下降,而D_(3)OBJECTIVE To investigate the effect of dopamine receptor 3(D_(3)R)on fear memory induced by intense electric shocks and the possible neurobiological mechanism.METHODS①To prevent pain threshold differences from influencing the effect of intense electric shocks,wild-type(WT)and D_(3)R knockout mice(D_(3)R^(-/-))were used in the Hargreaves test to evaluate their basal pain threshold,with the paw withdrawal latency(PWL)as the observation index.②WT and D_(3)R^(-/-)mice were divided into control groups and model groups,respectively.On the training day(the first day,D 1),the model groups received inescapable electric shocks(1.5 mA,10 s,10 s interval,15 cycle)while the control groups did not.Contextual fear tests were conducted on D2,D7,D10,D14,and D16 after training,with the percentage of freezing time(FT)as the observation index to evaluate fear memory acquisition induced by contextual cues.On D17,after the model groups showed no more fear responses to contextual cues,they were re-stimulated with low-intensity current(0.5 mA,10 s,10 s interval,15 cycle)to evoke fear memory.The two control groups did not receive any shocks.Contextual fear tests were conducted on day 18,and the FT%of each group was observed to evaluate fear memory retrieval induced by contextual cues.③Another cohort of WT and D_(3)R^(-/-)mice was used to further investigate the underlying neural mechanism,with the same grouping and treatment as in②.Real-time dynamic changes in calcium signals of dopamine(DA)neurons in the ventral tegmental area(VTA)of WT and D_(3)R^(-/-)mice were detected using fiber photometry during electric shocks.The fluorescence area under the curve(AUC)was used as the indicator to quantify the excitability of DA neurons.RESULTS①In the Hargreaves test,there was no significant difference in PWL between D_(3)R^(-/-)mice and WT mice,indicating the two genotype mice had no significant differences in the basal pain threshold.②Compared with the WT control group,the percentage of FT of the WT model group significantly increased

关 键 词：多巴胺3型受体 恐惧记忆 中脑腹侧被盖区 多巴胺 

分 类 号：R964[医药卫生—药理学]