Kohn Jordan N, Snyder-Mackler Noah, Barreiro Luis B, Johnson Zachary P, Tung Jenny, Wilson Mark E
Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30322, USA.
Department of Evolutionary Anthropology, Duke University, Durham, NC, 27708, USA; Duke Center for Aging, Duke University, Durham, NC, 27708, USA.
Psychoneuroendocrinology. 2016 Dec;74:179-188. doi: 10.1016/j.psyneuen.2016.09.005. Epub 2016 Sep 12.
Low social status is frequently associated with heightened exposure to social stressors and altered glucocorticoid regulation by the hypothalamic-pituitary-adrenal (HPA) axis. Additionally, personality differences can affect how individuals behave in response to social conditions, and thus may aggravate or protect against the effects of low status on HPA function. Disentangling the relative importance of personality from the effects of the social environment on the HPA axis has been challenging, since social status can predict aspects of behavior, and both can remain stable across the lifespan. To do so here, we studied an animal model of social status and social behavior, the rhesus macaque (Macaca mulatta). We performed two sequential experimental manipulations of dominance rank (i.e., social status) in 45 adult females, allowing us to characterize personality and glucocorticoid regulation (based on sensitivity to the exogenous glucocorticoid dexamethasone) in each individual while she occupied two different dominance ranks. We identified two behavioral characteristics, termed 'social approachability' and 'boldness,' which were highly social status-dependent. Social approachability and a third dimension, anxiousness, were also associated with cortisol dynamics in low status females, suggesting that behavioral tendencies may sensitize individuals to the effects of low status on HPA axis function. Finally, we found that improvements in dominance rank increased dexamethasone-induced acute cortisol suppression and glucocorticoid negative feedback. Our findings indicate that social status causally affects both behavioral tendencies and glucocorticoid regulation, and that some behavioral tendencies also independently affect cortisol levels, beyond the effects of rank. Together, they highlight the importance of considering personality and social status together when investigating their effects on HPA axis function.
社会地位低下常常与更多地暴露于社会压力源以及下丘脑 - 垂体 - 肾上腺（HPA）轴对糖皮质激素调节的改变有关。此外，人格差异会影响个体对社会状况的行为反应方式，进而可能加重或抵御低社会地位对HPA功能的影响。区分人格与社会环境对HPA轴影响的相对重要性一直具有挑战性，因为社会地位可以预测行为的某些方面，而且两者在整个生命周期中都可能保持稳定。为此，我们研究了社会地位和社会行为的动物模型——恒河猴（猕猴）。我们对45只成年雌性恒河猴的优势等级（即社会地位）进行了两次连续的实验性操纵，使我们能够在每只个体处于两种不同优势等级时，对其人格和糖皮质激素调节（基于对外源性糖皮质激素地塞米松的敏感性）进行特征描述。我们确定了两种行为特征，称为“社交亲和力”和“大胆”，它们高度依赖于社会地位。社交亲和力以及第三个维度——焦虑，也与低社会地位雌性的皮质醇动态变化有关，这表明行为倾向可能使个体对低社会地位对HPA轴功能的影响更加敏感。最后，我们发现优势等级的提高增强了地塞米松诱导的急性皮质醇抑制和糖皮质激素负反馈。我们的研究结果表明，社会地位因果性地影响行为倾向和糖皮质激素调节，并且一些行为倾向也独立于等级影响之外，对皮质醇水平产生影响。总之，它们凸显了在研究人格和社会地位对HPA轴功能的影响时，将两者综合考虑的重要性。
