Williams College Neuroscience Program, Williamstown, MA 01267, USA.
Neurosci Lett. 2013 Mar 1;536:47-51. doi: 10.1016/j.neulet.2012.12.048. Epub 2013 Jan 8.
The post-weaning social environment has profound effects on behavior and physiology in rodents. Social isolation increases anxiety-like behaviors and novelty-induced locomotor activity, while environmental enrichment decreases these behaviors. In some cases, the effects of social isolation are ameliorated by repeated handling. The goal of the present study was to determine whether the effects of handling differ in rats reared in social isolation and those reared in an enriched environment. After weaning, male Long-Evans rats were housed individually (ISO)(3) or in groups in an enriched environment (EE). During adulthood, rats from each housing condition received four, once-daily, brief handling sessions or remained undisturbed in the home cage. All rats were then tested in the open field, elevated plus maze, and for behavioral responses to d-amphetamine (1.0mg/kg). EE rats spent more time on the open arms of the elevated plus maze and were more likely than ISO rats to emerge from the start box in the open field, suggesting lower anxiety. Handling significantly decreased open arm time in EE rats and marginally increased open arm time in ISO rats. Housing condition did not affect amphetamine-stimulated locomotor activity, but handling altered the time course of the amphetamine response. ISO rats exhibited significantly fewer stereotyped behaviors than did EE rats, but repeated handling eliminated this difference. These findings support previously published studies that suggest brief handling of adult rats may at least partially ameliorate the effects of post-weaning social isolation on anxiety-like behaviors and psychostimulant sensitivity. Furthermore, there are complex interactions between the effects of housing environment and handling, suggesting that handling may be perceived and/or processed differently, depending on the animal's housing environment.
断奶后的社会环境对啮齿动物的行为和生理有深远的影响。社会隔离会增加类似焦虑的行为和新奇诱导的运动活动，而环境丰富则会减少这些行为。在某些情况下，反复处理可以减轻社会隔离的影响。本研究的目的是确定在社会隔离和丰富环境中饲养的大鼠中，处理的效果是否不同。断奶后，雄性长耳大鼠被单独饲养（ISO）（3）或在丰富环境中分组饲养（EE）。在成年期，来自每种饲养条件的大鼠接受四次，每日一次，短暂的处理，或留在笼中不受干扰。然后，所有大鼠都在开阔场、高架十字迷宫中进行测试，并对 d-苯丙胺（1.0mg/kg）的行为反应进行测试。EE 大鼠在高架十字迷宫的开放臂上花费的时间更多，并且比 ISO 大鼠更有可能从开阔场的起始箱中出现，表明焦虑程度较低。处理显著减少了 EE 大鼠的开放臂时间，并且略微增加了 ISO 大鼠的开放臂时间。饲养条件不影响安非他命刺激的运动活动，但处理改变了安非他命反应的时程。ISO 大鼠比 EE 大鼠表现出更少的刻板行为，但反复处理消除了这种差异。这些发现支持了先前发表的研究，即表明对成年大鼠进行短暂处理至少可以部分减轻断奶后社会隔离对类似焦虑的行为和精神兴奋剂敏感性的影响。此外，饲养环境和处理的影响之间存在复杂的相互作用，这表明处理可能会根据动物的饲养环境而被感知和/或处理方式不同。
