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Student Prize Award Abstract
2004 Oral Paper Honorable Mention

DIFFERENTIAL EFFECTS OF STRESSORS ON THE HYPOTHALAMIC-PITUITARY-ADRENAL HORMONES CORTISOL AND DHEAS IN ADULT MALE RHESUS MACAQUES

N. Maninger1,2; J. P. Capitanio1,2; S. A. Blozis1; J. D. Ruys3 and S. P. Mendoza1,2
1Department of Psychology, University of California - Davis, One Shields Ave, Davis, CA, 95616, USA, 2California National Primate Research Center, 3Department of Physiology and Pharmacology, Wake Forest School of Medicine

Although both cortisol and dehydroepiandrosterone-sulfate (DHEAS) are secreted from the adrenal in response to ACTH, they are thought to have opposing effects. While cortisol is immunosuppressive, DHEAS is purported to increase immunocompetence. Using banked samples, we compared DHEAS concentrations of 36 adult male rhesus macaques (Macaca mulatta) inoculated with either simian immunodeficiency virus (SIV, n=18) or saline (n=18), and socialized daily in stable or unstable (i.e., stressful) social groups (Capitanio et al., 1998). Mixed-effects modeling was used to investigate the influence of inoculation condition and socialization condition (stable vs. unstable) over time for the control and SIV-inoculated subjects. Analysis revealed a significant change over time (p<.05), but no influence of SIV disease or daily social stress on DHEAS concentrations. Cortisol concentrations differed by social condition, but generally were not influenced by inoculation condition. In a second study, 33 adult males were physically restrained and their HPA response evaluated (Ruys et al, in press). ANOVA revealed that both cortisol and DHEAS increased in response to a physical stressor (p<.05), showed a circadian rhythm (p<.05), and were suppressed by dexamethasone (p<.05). Like cortisol, DHEAS shows intraindividual consistency as well as a circadian rhythm and signs of a circannual rhythm. This is the first evidence in rhesus macaques to demonstrate that social stress affects cortisol but not DHEAS, SIV inoculation affects neither hormone, and physical stress affects both.


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