生命早期孤养对小鼠应激易感性的影响

Effect of early maternal separation on susceptibility to stress of adult mice

目的:观察生命早期母婴分离对小鼠应激易感性及认知能力的影响。方法:新生的小鼠于出生后第2天随机分为正常饲养组(N组:正常饲养,n=9)、长时间母婴分离组(LMS组:分离3 h,n=9)及短时间母婴分离组(BMS组:分离15 min,n=8)。3组小鼠出生后21 d断乳,断乳后常规饲养。小鼠成年后,用幽闭+电击的方法对3组小鼠给予急性应激,应激之后借助旷场实验、高架十字迷宫、水迷宫实验评价小鼠的情绪及学习记忆能力。结果:在旷场实验中,与N组比较,LMS及BMS组小鼠的外周路程明显增加,差异具有统计学意义(P<0.05);在高架十字迷宫中,LMS组较N组进入闭臂次数明显增多,差异具有统计学意义(P<0.05),BMS组与N组比较差异不具有统计学意义;在水迷宫实验中LMS组与BMS组小鼠的成绩与N组比较差异均无统计学意义。结论:①生命早期长时间母婴分离可以增强小鼠应激易感性,而短时间母婴分离影响不显著;②生命早期母婴分离对应激后小鼠的认知能力影响不明显。

Objective： To assess the effects of the early maternal separation （MS） paradigm on susceptibil-ity to stress and the cognitive abilities of adult mice. Methods： Mice were randomly divided into 3 groups： normal feeding group （N： n=9）, long maternal separation （LMS： 3 hour, n=9） and brief maternal separations（BMS： 15 min, n=8 ） from postnatal 2-21 days. During adulthood, 3 groups mice received acute unpredictable mild stress of 3 days. The learning and memory abilities were measured by Morris water maze and behavior was measured by open-field test and Elevated Plus Maze after stress. Results： Compared with the control group, LMS increased number of crossing and distance in peripheral area （P〈0.05）, and in the total area of open field （P〈0.05）. LMS enhanced exploration of closed arms in the elevated plus maze （P〈0.05）. But, there is no unified conclusion about the effects of susceptibility to stress of adult mice in BMS. However in the Morris water maze, there is no significant difference in three groups in the learning and memory abilities. It indicated that early maternal separation increased susceptibility of anxiety-like behavior. Conclusion： Early maternal separation can in- crease susceptibility to stress of adult mice, there is no significant difference in three groups in the learning and memory abilities.