Venegas Jassmyn J, Weisz Jacob M, Choi Chan Young, Herringshaw Ren E, Nabelsi Omar A, Liang Nu-Chu
Department of Psychology, University of Illinois Urbana-Champaign, Champaign, Illinois, USA.
Division of Nutritional Sciences, University of Illinois Urbana-Champaign, Urbana, Illinois, USA.
Physiol Rep. 2025 Jan;13(2):e70184. doi: 10.14814/phy2.70184.
The effects of social isolation (SI) during middle age remain unclear, so we tested the hypothesis that SI would lead to an increase in impulsive choice (IC), anxiety-like behavior, and metabolic dysfunction in middle-aged rats. Male and female rats were housed individually or in groups of four with same-sex housing mates at 11 months of age. Two months later, IC behavior was assessed using a delay-discounting task and anxiety-like behavior through a novelty-suppressed feeding (NSF) task. Lastly, glucose tolerance and insulin sensitivity following exposure to a high-fat diet were assessed using an oral glucose tolerance test (OGTT) and an insulin tolerance test (ITT). The results showed that socially isolated rats displayed more IC behavior than did group-housed rats of both sexes. However, no significant effect of housing was evident in the NSF task, OGTT, or ITT. Male rats had a higher plasma insulin concentration and insulin resistance index compared to females. Our findings demonstrate that SI in middle age is sufficient to increase IC behavior and highlight inherent sex-specific differences in metabolic profiles. These findings underscore the importance of investigating mechanisms that underlie the effects of social isolation during different stages of life.
中年时期社会隔离（SI）的影响尚不清楚，因此我们验证了这样一个假设：社会隔离会导致中年大鼠的冲动选择（IC）增加、出现焦虑样行为以及代谢功能障碍。雄性和雌性大鼠在11个月大时单独饲养或与同性同伴一起以四只一组的方式饲养。两个月后，通过延迟折扣任务评估冲动选择行为，并通过新奇抑制摄食（NSF）任务评估焦虑样行为。最后，使用口服葡萄糖耐量试验（OGTT）和胰岛素耐量试验（ITT）评估高脂饮食后的葡萄糖耐量和胰岛素敏感性。结果表明，与两性群居大鼠相比，社会隔离的大鼠表现出更多的冲动选择行为。然而，在NSF任务、OGTT或ITT中，饲养方式没有明显的显著影响。与雌性大鼠相比，雄性大鼠的血浆胰岛素浓度和胰岛素抵抗指数更高。我们的研究结果表明，中年时期的社会隔离足以增加冲动选择行为，并突出了代谢特征中固有的性别差异。这些发现强调了研究不同生命阶段社会隔离影响背后机制的重要性。
