Abstract # 946 Poster # 64:

Scheduled for Thursday, August 18, 2005 07:00 PM-09:00 PM: (Cambridge/Oxford Room) Poster Presentation

DHEAS and cortisol response of rhesus macaques to physical restraint and dexamethasone suppression

N. Maninger1,2, S. P. Mendoza1,2, J. P. Capitanio1,2 and J. D. Ruys3
1Psychology Department, University of California, One Shields Ave, Davis, CA 95616, USA, 2California National Primate Research Center, Davis, CA, 3Psychology Department, Evergreen Valley College, San Jose, CA
     Although glucocorticoids are stress-responsive, few studies have investigated dehydroepiandrosterone-sulfate (DHEAS), an adrenal androgen whose secretion is also stimulated by ACTH. Using banked samples, we compared DHEAS changes to published cortisol responses to physical restraint in 36 adult male rhesus macaques (Ruys et al., 2004). Monkeys were chair restrained for two hours for seven consecutive days and blood samples were collected during sessions one and seven immediately upon placement in the chair and 15, 30, 60 and 120 minutes later. Repeated-measures ANOVA (α = 0.05) revealed that during session one of consecutive chair restraint both cortisol and DHEAS increased, although cortisol increased more rapidly than DHEAS. By session seven, adrenocortical response was diminished for both hormones but DHEAS preserved the incremental increase whereas cortisol did not. To evaluate negative feedback the response to chair restraint was also examined following dexamethasone pretreatment on two occasions before and after consecutive chair restraint. As with cortisol, dexamethasone pretreatment resulted in lower DHEAS. During the first dexamethasone session, animals were inexperienced with chair restraint and low dose dexamethasone didn't fully block the stress-response; surprisingly, DHEAS showed a greater and earlier incremental response than cortisol. By the second dexamethasone session, animals had had eight sessions of chair experience and neither hormone increased in response to restraint. These are the first data to demonstrate that DHEAS and cortisol are differentially affected by stress, dexamethasone suppression, and experience.