背景因素、适应时间及物体位置对小鼠新事物识别的影响

摘要

目的 观察不同背景因素、适应时间及物体位置对小鼠新事物识别(NOR)的影响,评价小鼠学习记忆能力. 方法 50只8-12周的雄性昆明小鼠,随机分为4组,用于4个测验.盒子背景(黑盒、白盒)的测试(10只),空盒适应次数(1次、2次和3次)测试(15只),物体放置位置(角落、半角落和中间)测试(15只),不同事物适应次数(1次和2次)测试(10只).通过视频跟踪记录小鼠在盒子内的活动轨迹,统计其探索新旧事物的时间,计算小鼠对新事物的鉴别指数(DI)来评价各组小鼠的学习记忆情况. 结果 黑盒组小鼠对事物探索的总时间比白盒组明显更高(P＜0.05);小鼠在空盒适应1次和2次对新事物的DI值较旧事物无明显差别,但适应3次具有明显差异(P＜0.05);三种不同物体放置位置对小鼠探索物体的时间和DI值无显著影响;事物适应2次组的小鼠探索新物体的时间与1次组相比显著降低(P＜0.05);小鼠对新事物的DI值在3,5,7和10 min测试时间点上无明显差异. 结论 进行NOR测试时,选择黑色背景盒子及让小鼠在空盒适应3次可较好地评价小鼠学习记忆能力,不同物体放置位置对小鼠新事物识别影响较小.另外,选择事物适应1次和3 min的测试时间即可,其既能保证有较稳定的DI值,也能节省实验时间.%Objective To investigate the efficacy of novel object recognition(NOR) test in assessment of learning and memory ability in KM mice in different experimental conditions.Methods Fifty male KM mice(8-12 weeks)were randomly divided into 4 groups for four experiments:10 mice were used for background experiment (white or black box),15 mice were used for environment adaptation time experiment(once,twice or three times),15 mice were used for object position experiment (corner,half-corner or centre),and 10 mice were used for familiar object adaptation time experiment(once or twice).The locomotor tracks in the box were recorded.The exploration time for familiar or new object and discrimination index(DI) of new object were analyzed.Results The total exploration time in black box group was significantly longer than in white box group(P ＜ 0.05).The DI value of new object and familiar object had no significant difference when mice adapted the enviroment for once or twice,however there was significant difference after three times adaption(P ＜ 0.05).The object position experiment showed that different position had no influence on the exploration time and new object DI value.The total exploration time in the group of object adaptation for twice was significantly shorter than that in the group of object adaptation for once (P ＜ 0.05).The new object DI value had no significant difference among various time points (3,5,7 and 10 min).Conclusion In NOR experiment,black box and three-times environment adaptation may be more proper experimental conditions to evaluate novel object recognition ability of mice.The object position and object adaptation times have little influence on the new object DI value.To adapt object for once and observe for 3 min in the test period can not only efficiently evaluate novel object recognition ability of mice,but also save experimental time.