Psychosocial stress is the major form of stress faced by children and adolescents and is an important risk factor for the development of mental illnesses. Chronic social defeat stress (CSDS) is a preclinical mouse model that induces an entire spectrum of phenotypes with similar interindividual variability as seen in humans. Following CSDS, adult male mice have been characterized as being either susceptible or resilient to emotional stress on the basis of their social interactions, which was reported to be highly correlated with sucrose preference (SP) when measured after the last defeat episode.

We studied adolescent male C57BL/6 mice (30 days old) for susceptibility and resilience to social avoidance, anhedonia and anxiety-like behaviors, body weight change and basal blood corticosterone concentrations after 10 days of CSDS. Defeated adolescents showed reduced SP, reduced social interaction time (with an unknown adolescent male from their same strain), reduced weight gain and higher basal blood corticosterone concentration when compared to nondefeated mice. Only a small proportion of defeated adolescents were either totally susceptible (20%) or totally resilient (30%) in both the SP and social avoidance tests. The remaining defeated mice had a distinct behavioral impairment - susceptible in one test and resilient in the other. Surprisingly, behaviorally resilient defeated adolescents were the most affected population in terms of both endocrine/physiological outcomes. These findings illustrate that, contrary to prior assumptions in adults, the CSDS responses are more complex and singular in adolescents, and caution should be taken for the correct interpretation of those phenotypes. We propose a better characterization of social defeat stress responses as a critical step to advance our understanding of the mechanisms behind stress resilience that translate to human experience.

社会心理压力是儿童和青少年面临的主要压力形式，并且是发展精神疾病的重要危险因素。慢性社交挫败应激（CSDS）是一种临床前小鼠模型，可诱导人与人之间具有相似个体差异的整个表型谱。继CSDS后，成年雄性小鼠的社交互动已被表征为对情绪压力敏感或具有抵抗力，据报道，在最后一次失败发作后进行测量，这与蔗糖偏爱（SP）高度相关。

我们研究了30天大的青春期雄性C57BL / 6小鼠对社交回避，快感和焦虑症行为，体重变化和基础血皮质激素浓度的敏感性和适应力。与未败血症的小鼠相比，败败的青少年表现出SP降低，社交互动时间减少（与来自同一品系的青春期男性未知），体重减轻和基础血皮质酮浓度升高。在SP和社交回避测试中，只有一小部分被击败的青少年完全敏感（20％）或完全有弹性（30％）。其余被击败的小鼠有明显的行为障碍-在一项测试中易感，在另一项测试中具有弹性。出奇，就内分泌/生理结果而言，在行为上具有韧性的被击败青少年是受影响最大的人群。这些发现表明，与成人先前的假设相反，CSDS反应在青少年中更为复杂和奇异，应谨慎对待那些表型。我们建议更好地表征社会挫败压力反应，这是提高我们对转化为人类经验的压力弹性背后机制的理解的关键步骤。