Tamashiro Kellie L K, Nguyen Mary M N, Ostrander Michelle M, Gardner Stacy R, Ma Li Yun, Woods Stephen C, Sakai Randall R
Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45237, USA.
Am J Physiol Regul Integr Comp Physiol. 2007 Nov;293(5):R1864-74. doi: 10.1152/ajpregu.00371.2007. Epub 2007 Sep 12.
Social stress resulting from dominant-subordinate relationships is associated with body weight loss and altered body composition in subordinate (SUB) male rats. Here, we extend these findings to determine whether stress-induced changes in energy homeostasis persist when the social stress is removed, and the animal is allowed to recover. We examined body weight (BW), body composition, and relevant endocrine measures after one or two cycles of 14 days of social stress, each followed by 21 days of recovery in each rat's individual home cage. SUB lost significantly more BW during social housing in a visible burrow system (VBS) compared with dominant (DOM) animals. Weight loss during social stress was attributable to a decrease in adipose tissue in DOM and SUB, with an additional loss of lean tissue in SUB. During both 21-day recovery periods, DOM and SUB regained lost BW, but only SUB were hyperphagic. Following recovery, SUB had a relatively larger increase in adipose tissue and plasma leptin compared with DOM, indicating that body composition changes were dependent on social status. Control animals that were weight matched to SUB or male rats exposed to the VBS environment without females, and that did not form a social hierarchy, did not exhibit changes in body composition like SUB in the VBS. Therefore, chronic social stress causes social status-dependent changes in BW, composition and endocrine measures that persist after repeated stress and recovery cycles and that may ultimately lead to metabolic disorders and obesity.
在从属（SUB）雄性大鼠中，由主导-从属关系导致的社会压力与体重减轻和身体成分改变有关。在此，我们扩展这些发现，以确定当社会压力消除且动物得以恢复时，应激诱导的能量稳态变化是否持续存在。我们在每只大鼠单独的饲养笼中，对经过14天社会压力的一个或两个周期（每个周期后接着21天恢复）的大鼠，检查其体重（BW）、身体成分和相关内分泌指标。与主导（DOM）动物相比，SUB在可见洞穴系统（VBS）中的群居期间体重显著减轻更多。社会压力期间的体重减轻归因于DOM和SUB的脂肪组织减少，SUB还额外损失了瘦组织。在两个21天的恢复期内，DOM和SUB都恢复了减轻的体重，但只有SUB出现食欲亢进。恢复后，与DOM相比，SUB的脂肪组织和血浆瘦素增加相对更多，表明身体成分变化取决于社会地位。体重与SUB匹配的对照动物，或暴露于无雌性的VBS环境且未形成社会等级的雄性大鼠，并未表现出像VBS中的SUB那样的身体成分变化。因此，慢性社会压力会导致体重、成分和内分泌指标出现依赖于社会地位的变化，这些变化在反复的压力和恢复周期后持续存在，最终可能导致代谢紊乱和肥胖。
