Chronic social defeat stress (CSDS) has been found to produce different impacts on anxiety-like behaviors, spatial cognitive function and memory in rodents with different susceptibilities. However, the impacts of chronic social defeat on social behaviors in adult male mice with different susceptibilities to social defeat and the underlying mechanisms in the brain remain unclear. In the present study, we found that ten days of social defeat reduced the tendency of susceptible adult male C57 mice to approach an unfamiliar individual and increased their avoidance of an unfamiliar CD-1 mouse but had no effects on resilient individuals. In addition, CSDS enhanced anxiety-like behavior in susceptible animals, but produced no effects in the resilient group. Meanwhile, CSDS increased the number of corticotropin-releasing factor (CRF)-positive neurons in the paraventricular nucleus of the hypothalamus and CRF-R2-positive neurons in the accumbens nucleus shell in both resilient and susceptible animals. CSDS increased the number of CRF-R1-positive neurons and CRF-R1 mRNA expression in the prelimbic cortex (PrL) and the number of CRF-R2-positive neurons in the basolateral amygdala, but reduced the number of CRF-R2-positive neurons and mRNA expression in the PrL in susceptible animals. Therefore, the different effects of CSDS on sociability and anxiety-like behavior in mice with different susceptibilities may be associated with region- and type-specific alterations in CRF receptor levels. These findings help us understand the underlying mechanism by which social stress affects emotion and social behavior and provides an important basis for the treatment of disorders of social and emotional behavior caused by social stress.

中文翻译：

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慢性社交失败对具有不同敏感性的成年雄性C57小鼠的社交行为和大脑CRF系统的不同影响。

已发现慢性社交挫败压力（CSDS）对具有不同易感性的啮齿动物的焦虑样行为，空间认知功能和记忆产生不同的影响。然而，慢性社交挫败对成年雄性小鼠的社交行为具有不同的影响，而成年雄性小鼠对社交挫败的敏感性不同，大脑的潜在机制尚不清楚。在本研究中，我们发现社交失败的十天减少了易感的成年雄性C57小鼠接近陌生个体的趋势，并增加了对陌生CD-1小鼠的回避，但对弹性个体没有影响。此外，CSDS增强了易感动物的焦虑样行为，但对弹性组没有影响。与此同时，CSDS增加了弹性和易感动物下丘脑室旁核中促肾上腺皮质激素释放因子（CRF）阳性神经元的数量以及伏隔核壳中CRF-R2阳性神经元的数量。CSDS增加了前外侧皮层（PrL）中CRF-R1阳性神经元的数量和CRF-R1 mRNA的表达以及基底外侧杏仁核中CRF-R2阳性神经元的数量，但减少了CRF-R2阳性神经元的数量易感动物中PrL中的mRNA和mRNA表达。因此，CSDS对易感性不同的小鼠的社交性和焦虑样行为的不同影响可能与CRF受体水平的区域和类型特异性改变有关。