Ryu Vitaly, Yoo Sang Bae, Kang Dong-Won, Lee Jong-Ho, Jahng Jeong Won
Department of Oral and Maxillofacial Surgery, Dental Research Institute, Seoul National University School of Dentistry, Seoul, 110-768, Korea.
Brain Res. 2009 Oct 27;1295:127-34. doi: 10.1016/j.brainres.2009.08.006. Epub 2009 Aug 8.
Neonatal maternal separation (MS) in rats has been reported to result in permanent dysfunctions of the hypothalamic-pituitary-adrenal axis and the development of anxiety- and depression-like behaviors later in life. In this study, we examined the effects of post-weaning social isolation stress on food intake and body weight gain of rats with MS experience. MS was performed daily for 180 min during the first 2 weeks of birth and nonhandled control (NH) pups were left undisturbed. Weanling male pups were caged either in a group of three or singly (social isolation), and then subjected to behavioral sessions for anxiety- or depression-like behaviors at 2 months of age. Social isolation following MS experience, but neither MS nor social isolation alone, significantly increased food intake and weight gain. MS pups showed increased immobility in forced swim test, compared to NH pups, regardless of their housing conditions. In elevated plus maze test, group-caged MS pups spent less time in the open arms and more time in the closed arms than group-caged NH pups, but social isolation did not further affect the arm stay of MS pups. However, statistical analyses revealed an interaction between MS and social isolation not only in the time spent in each arms, but also in defecation scores during the ambulatory activity test. These results suggest that post-weaning social isolation may promote hyperphagia and weight gain in young rats that experienced neonatal maternal separation, perhaps, in relation with its impact on the psycho-emotional behaviors of MS pups.
据报道，新生大鼠与母鼠分离（MS）会导致下丘脑-垂体-肾上腺轴永久性功能障碍，并在其日后生活中出现类似焦虑和抑郁的行为。在本研究中，我们检测了断奶后社会隔离应激对有MS经历的大鼠食物摄入量和体重增加的影响。在出生后的前2周，每天对大鼠进行180分钟的MS操作，未处理的对照（NH）幼崽不做干扰。将断奶后的雄性幼崽三只一组或单独饲养（社会隔离），然后在2月龄时对其进行类似焦虑或抑郁行为的行为学测试。有MS经历后的社会隔离，但单独的MS或社会隔离均未显著增加食物摄入量和体重增加。与NH幼崽相比，无论饲养条件如何，MS幼崽在强迫游泳试验中的不动时间增加。在高架十字迷宫试验中，与三只一组饲养的NH幼崽相比，三只一组饲养的MS幼崽在开放臂中停留的时间更少，在封闭臂中停留的时间更多，但社会隔离并未进一步影响MS幼崽在各臂中的停留情况。然而，统计分析显示，MS和社会隔离之间不仅在各臂停留时间上存在交互作用，而且在动态活动试验中的排便评分上也存在交互作用。这些结果表明，断奶后社会隔离可能会促进有新生期母鼠分离经历的幼鼠出现摄食亢进和体重增加，这可能与其对MS幼崽心理情绪行为的影响有关。
