不同应激方式对小鼠恐惧记忆及其泛化的影响

Effects of different stress paradigms on fear memory and its generalization in mice

目的 研究反复禁锢应激(RRS)和单次延长应激(SPS)对小鼠恐惧记忆及其泛化的影响。方法 将8周龄雄性C57BL/6J小鼠随机分为4组,实验组分别采用RRS和SPS处理,相应对照组未经任何处理。利用高架十字迷宫实验检测小鼠的焦虑水平,利用场景恐惧实验检测小鼠的恐惧记忆及其泛化。结果 应激处理7 d后,RRS组和SPS组小鼠与其对照组相比均表现出明显的焦虑样行为(t=5.043、5.364,P<0.01)。RRS组小鼠电击24 h后在电击场景的僵立时间与对照小鼠相比无明显差别(P>0.05),电击7、14 d后RRS小鼠在电击场景的僵立时间百分比仍明显高于新场景(P<0.001)。SPS组小鼠电击24 h后在电击场景的僵立时间百分比明显高于对照组(P<0.01),两组小鼠在电击场景的僵立时间百分比均高于新场景;电击7 d后SPS小鼠在电击场景的僵立时间与新场景相比无明显差别,对照小鼠在电击场景的僵立时间百分比仍明显高于新场景。结论 SPS可增强小鼠场景恐惧记忆并促进其泛化,RRS对小鼠的场景恐惧记忆及其泛化无明显影响。

Objective To investigate the effects of repeated restraint stress(RRS)and single prolonged stress(SPS)on fear memory and its generalization in mice.Methods Eight-week-old male C57BL/6J mice were randomly divided into four groups.The experimental groups were treated with either RRS or SPS,while the corresponding control groups underwent no treatment.Anxiety levels were assessed using the elevated plus maze test,and fear memory and its generalization were evaluated using the fear conditioning test.Results Seven days after stress treatment,both RRS and SPS mice exhibited significant anxiety-like behaviors compared to control mice(t=5.043,5.364;P<0.01).Twenty-four hours after shock,the freezing time in the shock context did not differ significantly between RRS mice and control mice(P>0.05).However,on days 7 and 14 after shock,the freezing time in the shock context was still significantly higher in RRS mice compared to a new context(P<0.001).For SPS mice,their freezing levels in the shock context 24 hours post-shock were significantly higher than those in control mice(P<0.01).Both groups showed higher freezing time in the shock context compared to a new context;however,7 days post-shock,the freezing time in the shock context for SPS mice did not differ significantly from that in the new context,whereas control mice showed significantly higher freezing time in the shock context compared to the new context.Conclusion SPS enhances contextual fear memory and promotes its generalization in mice,while RRS has no significant impact on contextual fear memory or its generalization.