Srinivasan Durga J, Kapgal Vijayakumar, Morris Richard G M, Chattarji Sumantra
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India.
The University of Trans-Disciplinary Health Sciences and Technology, Bangalore 560064, India.
Proc Natl Acad Sci U S A. 2025 May 13;122(19):e2412314122. doi: 10.1073/pnas.2412314122. Epub 2025 May 9.
Establishing a dominance hierarchy in social organisms is important for access to resources. Stress has been proposed as a major factor influencing an animal's likely position in a social hierarchy. Although individual differences in vulnerability to stress are increasingly recognized, how social hierarchy affects vulnerability remains relatively understudied. Here, we examined how the social dominance status of adult male Sprague-Dawley rats influences their response to stress in interactions with a familiar animal living in the same cage, and separately when confronting an unfamiliar rat of uncertain dominance status from another cage, using the tube test. Having determined the relatively stable within-cage social dominance status of animals, half were subjected to a single episode of 2-h immobilization stress. Cagemates, both control and stressed rats, again faced one another 1 d and 10 d after stress. First, the predetermined hierarchical rank among familiar cagemates was relatively unaffected by stress. However, second, the same stress had a differential impact in competitions between unfamiliar rats. Socially dominant control rats continued to win competitions but subordinate control rats, that had previously lost, sometimes started to win against previously dominant rats that had been stressed. Strikingly, subordinate stressed rats displayed consistent submissive-like behavior and they alone showed differential effects on dendritic spine density in the amygdala. Thus, an individual's social rank can influence its response to stress, an effect that is detectable in interactions with unfamiliar animals. These findings provide an additional dimension to animal models of stress used for exploring facets of social anxiety and withdrawal in stress-related psychiatric disorders.
在社会生物中建立优势等级制度对于获取资源很重要。压力被认为是影响动物在社会等级制度中可能地位的一个主要因素。尽管人们越来越认识到个体对压力的易感性存在差异，但社会等级制度如何影响易感性仍相对缺乏研究。在这里，我们使用管子测试，研究了成年雄性斯普拉格-道利大鼠的社会优势地位如何影响它们在与同笼生活的熟悉动物互动时以及分别与来自另一个笼子的优势地位不确定的陌生大鼠对峙时对压力的反应。在确定了动物在笼内相对稳定的社会优势地位后，一半动物接受了一次为期2小时的固定应激。应激1天和10天后，笼伴，即对照大鼠和应激大鼠，再次相互对峙。首先，熟悉的笼伴之间预先确定的等级地位相对不受应激影响。然而，其次，相同的应激在陌生大鼠之间的竞争中产生了不同的影响。社会优势的对照大鼠继续赢得竞争，但之前失败的从属对照大鼠有时开始战胜之前占优势但受到应激的大鼠。引人注目的是，从属应激大鼠表现出一致的类似顺从的行为，并且只有它们对杏仁核中的树突棘密度有不同影响。因此，个体的社会等级可以影响其对压力的反应，这种影响在与陌生动物的互动中是可检测到的。这些发现为用于探索与压力相关的精神疾病中社交焦虑和退缩方面的压力动物模型提供了一个新的维度。
