MacKay J C, Kent P, James J S, Cayer C, Merali Z
School of Psychology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; University of Ottawa Institute of Mental Health Research, 1145 Carling Avenue, Room 5432, Research Tower, Ottawa, ON K1Z 7K4, Canada.
School of Psychology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; Department of Psychiatry, University of Ottawa, Ottawa, ON K1N 6N5, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada; University of Ottawa Institute of Mental Health Research, 1145 Carling Avenue, Room 5432, Research Tower, Ottawa, ON K1Z 7K4, Canada.
Physiol Behav. 2017 Aug 1;177:113-121. doi: 10.1016/j.physbeh.2017.04.002. Epub 2017 Apr 7.
In adult rats, access to a palatable diet can buffer against the effects of stressors. Approximately 10% of all adolescents are repeatedly victimized by their peers raising the possibility that palatable food consumption may be relevant to this developmental window. This study assessed the long-term impact of juvenile social defeat exposure on anxiety and depressive-like behavior and whether daily limited access to a palatable diet moderated these behavioral consequences. We also investigated the impact of the palatable diet on behavior during the defeat sessions. Juvenile rats were exposed to either a different adult resident rat (Stress) or handling (Control) from postnatal day (PD) 28-34. All rats had ad libitum access to either chow alone or both chow and limited access (4h/day) to palatable food commencing on PD 21. Results showed that during the defeat sessions, juvenile rats with access to the palatable diet spent less time in submissive postures and displayed significantly longer latencies to submit to the resident. In adulthood, previous exposure to juvenile social defeat resulted in a mild anxiogenic profile in the open field among rats with access to Chow only. Furthermore, defeated rats, regardless of diet, displayed reduced locomotor activity and increased social interaction as adults. These findings suggested only minimal enduring negative consequences from juvenile social defeat exposure which made it challenging to assess potential stress-buffering effects of the palatable diet. This was not the case during the defeat sessions where previous exposure to palatable food appeared protective against the acute stressor effects.
在成年大鼠中，接触美味食物可以缓冲应激源的影响。大约10%的青少年会反复受到同伴的欺负，这增加了食用美味食物可能与这个发育阶段相关的可能性。本研究评估了幼年社会挫败经历对焦虑和抑郁样行为的长期影响，以及每天有限地接触美味食物是否会减轻这些行为后果。我们还研究了美味食物在挫败过程中对行为的影响。从出生后第28天至34天，将幼年大鼠暴露于不同的成年常驻大鼠（应激组）或进行处理（对照组）。从出生后第21天开始，所有大鼠均可自由获取普通食物，或者同时获取普通食物和有限量（每天4小时）的美味食物。结果显示，在挫败过程中，能够获取美味食物的幼年大鼠采取顺从姿势的时间较少，并且向常驻大鼠屈服的潜伏期明显更长。在成年期，之前经历过幼年社会挫败的大鼠中，仅能获取普通食物的大鼠在旷场试验中表现出轻度的焦虑倾向。此外，无论饮食如何，遭受挫败的大鼠成年后运动活动减少，社交互动增加。这些发现表明，幼年社会挫败经历只会产生极小的持久负面后果，这使得评估美味食物潜在的应激缓冲作用具有挑战性。但在挫败过程中情况并非如此，之前接触美味食物似乎可以抵御急性应激源的影响。
