Background Previous studies suggest that persistent exposure to social stress in mammals may be associated with multiple physiological effects. Here, we examine the effects of social stress in rats, i.e. repeated social defeat, on behavior, hypothalamic–pituitary–adrenal (HPA)-axis and immune system. Methods A resident-intruder paradigm, where an intruder rat was exposed to social stress by a dominant resident rat for 1 hour each day for 7 consecutive days was used. The day after the last stress exposure in the paradigm the data were analyzed. Variation in social interaction was observed manually, whereas locomotion was analyzed off-line by a purpose-made software. Gene expression in the pituitary gland, adrenal gland and myeloid cells isolated from the spleen was measured by qPCR. Results The exposure to social stress induced decreased weight gain and increased locomotion. An increased nuclear receptor subfamily group C number 1 (NR3C1) expression in the pituitary gland was also shown. In myeloid cells harvested from the spleen, we observed decreased expression of the β 2 -adrenergic receptor (ADRB2) and β-arrestin-2 (ARRB2), but increased expression of interleukin-6 (IL-6). Subsequent analyses in the same cells showed that ARRB2 was negatively correlated with IL-6 following the stress exposure. Conclusion Our results show that that the experience of social stress in the form of repeated social defeat in rats is a potent stressor that in myeloid cells in the spleen promotes persistent inflammatory changes. Future research is needed to examine whether similar inflammatory changes also can explain the impact of social stress, such as bullying and harassment, among humans.

中文翻译：

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反复的社交失败会促进脾髓细胞的持续炎症变化；β-arrestin-2 (ARRB2) 表达降低，白细胞介素 6 (IL-6) 表达增加

背景 先前的研究表明，哺乳动物持续暴露于社会压力可能与多种生理效应有关。在这里，我们研究了社会压力对大鼠的影响，即反复的社会失败对行为、下丘脑-垂体-肾上腺 (HPA) 轴和免疫系统的影响。方法采用常驻-入侵者范式，其中入侵者大鼠连续 7 天每天暴露于占优势的常驻大鼠 1 小时的社会压力。在范式中最后一次压力暴露后的第二天，对数据进行了分析。手动观察社会互动的变化，而通过专用软件离线分析运动。通过 qPCR 测量从脾脏分离的垂体、肾上腺和骨髓细胞中的基因表达。结果 暴露于社会压力导致体重增加减少和运动增加。还显示垂体中核受体亚家族组 C 编号 1 (NR3C1) 表达增加。在取自脾脏的骨髓细胞中，我们观察到 β2-肾上腺素能受体 (ADRB2) 和 β-抑制蛋白-2 (ARRB2) 的表达降低，但白细胞介素-6 (IL-6) 的表达增加。随后在相同细胞中的分析表明，在应激暴露后，ARRB2 与 IL-6 呈负相关。结论 我们的结果表明，大鼠反复社交失败形式的社交压力体验是一种有效的压力源，脾脏中的髓细胞会促进持续的炎症变化。未来的研究需要检查类似的炎症变化是否也可以解释社会压力的影响，