Saltzman W, Prudom S L, Schultz-Darken N J, Wittwer D J, Abbott D H
Department of Biology, University of California, Riverside, CA 92521, USA.
Psychoneuroendocrinology. 2004 Feb;29(2):141-61. doi: 10.1016/s0306-4530(02)00159-2.
Behaviorally subordinate female common marmoset monkeys (Callithrix jacchus) exhibit pronounced, chronic reductions of circulating cortisol levels. Cortisol suppression in these animals is mediated in part by adrenocortical hyporesponsiveness to adrenocorticotropic hormone (ACTH). In addition, we hypothesized that social subordination may activate a central, neurally mediated mechanism to further inhibit hypothalamo-pituitary-adrenal function. In this study, therefore, we evaluated basal plasma cortisol and ACTH concentrations, as well as cortisol and ACTH responses to dexamethasone (DEX), in dominant and subordinate females to initially characterize such a mechanism. Morning plasma cortisol and ACTH levels were determined before, and 1, 2, and 3 days following administration of DEX (0.5, 1.0, or 5.0 mg/kg, IM) or saline. Baseline cortisol concentrations prior to DEX treatment were significantly lower in subordinate females than in dominants, as previously reported. However, ACTH concentrations in the same blood samples did not differ between the two groups. Furthermore, dominant and subordinate females showed similar cortisol and ACTH responses to DEX. These results indicate that reduced circulating cortisol levels in subordinate females are not associated with either altered circulating ACTH concentrations or enhanced responsiveness to glucocorticoid negative feedback. However, the finding that basal ACTH levels are not elevated in subordinate females as compared to dominants, in spite of low circulating cortisol concentrations, suggests that ACTH secretion in subordinate females is restrained by a steroid-independent inhibitory mechanism operating at the level of the brain or pituitary.
行为上处于从属地位的雌性普通狨猴（绢毛猴）表现出循环皮质醇水平明显且长期降低。这些动物的皮质醇抑制部分是由肾上腺皮质对促肾上腺皮质激素（ACTH）反应性降低介导的。此外，我们推测社会从属地位可能激活一种中枢神经介导机制，以进一步抑制下丘脑 - 垂体 - 肾上腺功能。因此，在本研究中，我们评估了优势和从属雌性的基础血浆皮质醇和ACTH浓度，以及对地塞米松（DEX）的皮质醇和ACTH反应，以初步表征这种机制。在给予DEX（0.5、1.0或5.0mg/kg，肌肉注射）或生理盐水之前、之后1、2和3天测定早晨血浆皮质醇和ACTH水平。如先前报道，DEX治疗前从属雌性的基线皮质醇浓度显著低于优势雌性。然而，两组相同血样中的ACTH浓度没有差异。此外，优势和从属雌性对DEX的皮质醇和ACTH反应相似。这些结果表明，从属雌性循环皮质醇水平降低与循环ACTH浓度改变或对糖皮质激素负反馈反应增强无关。然而，尽管循环皮质醇浓度较低，但与优势雌性相比，从属雌性基础ACTH水平未升高，这一发现表明，从属雌性的ACTH分泌受到大脑或垂体水平上一种不依赖类固醇的抑制机制的限制。
