Social suppression of cortisol in female marmoset monkeys: role of circulating ACTH levels and glucocorticoid negative feedback

Circadian cortisol secretion and circadian adrenal responses to ACTH are maintained in dexamethasone suppressed capuchin monkeys (Cebus apella)

“…To assess the role of the ACTH rhythm in generating the plasma cortisol rhythm in the capuchin monkey, we investigated the effect of dexamethasone treatment on clock time changes of plasma cortisol. Dexamethasone is a potent suppressor of ACTH in human and other species [Orth & Kovacs, 1998;Sage et al, 2002;Saltzman et al, 2004;Weaver et al, 2000]. In the capuchin, dexamethasone treatment suppressed the increases in ACTH observed at 0800 and 0200 h in control, non-suppressed animals and resulted in low flat ACTH levels along the four clock times studied.…”

“…The doses of ACTH and dexamethasone were selected based on data obtained in the marmoset (Callithrix jacchus), a New World monkey that like the capuchin, presents high plasma cortisol concentrations [Chrousos et al, 1982;Saltzman et al, 2000Saltzman et al, , 2004.…”

Social suppression of cortisol in female marmosets: Role of luteinizing hormone/chorionic gonadotropin

“…This dose of DEX suppresses plasma cortisol and ACTH concentrations in female marmosets for 2-3 days (Saltzman et al, 2004b). At 09:30-10:00 h the following morning, each animal received an IV injection of either 1 or 10 g/kg synthetic human ACTH 1¡39 (Sigma-Aldrich, St. Louis, MO, USA) in 0.5 ml/kg sterile saline.…”

“…Morning basal (i.e., non-stressed) cortisol concentrations decline markedly within 6-7 weeks following the onset of social subordination and anovulation, and can remain low for months to years (Abbott et al, 1997;Johnson et al, 1996;Saltzman et al, 1994Saltzman et al, , 1998Saltzman et al, , 2004bSaltzman et al, , in press, 2006. Diminished cortisol concentrations are associated with reduced adrenal responsiveness to adrenocorticotropic hormone (ACTH): subordinate females have basal plasma ACTH concentrations that are similar to those of dominants (Johnson et al, 1996;Saltzman et al, 2004b, in press), and therefore have reliably lower cortisol-to-ACTH ratios (Saltzman et al, in press).…”

Diurnal cycle in salivary cortisol levels in common marmosets

“…In addition, cortisol levels are known to be associated with social status among female common marmosets. Subordinate females have lower basal levels of plasma cortisol (Saltzman, SchultzDarken, Wegner, Wittwer, & Abbott, 1998) caused, in part, by dampened responsiveness of the adrenal cortex to adrenocorticotrophic hormone (Saltzman, Prudom, Schultz-Darken, & Abbott, 2000) and by some form of inhibition in the brain or pituitary gland (Saltzman, Prudom, Schultz-Darken, & Abbott, 2004).…”