Effect of Caloric Restriction on the 24-Hour Plasma DHEAS and Cortisol Profiles of Young and Old Male Rhesus Macaques


Address for correspondence: Henryk F. Urbanski, Ph.D., Division of Neuroscience, Oregon National Primate Research Center, 505 N.W. 185 th Avenue, Beaverton, OR 97006. Voice: 503-690-5306; fax: 503-690-5384. urbanski@ohsu.edu


Abstract: Although dietary caloric restriction (CR) can retard aging in laboratory rats and mice, it is unclear whether CR can exert similar effects in long-lived species, such as primates. Therefore, we tested the effect of CR on plasma levels of dehydroepiandrosterone sulfate (DHEAS), a reliable endocrine marker of aging. The study included six young (∼10 years) and ten old (∼25 years) male rhesus macaques, approximately half of the animals in each age group having undergone >4 years of 30% CR. Hourly blood samples were collected remotely for 24 hours, through a vascular catheter, and assayed for DHEAS and cortisol. Both of these adrenal steroids showed a pronounced diurnal plasma pattern, with peaks occurring in late morning, but only DHEAS showed an aging-related decline. More importantly, there was no significant difference in plasma DHEAS concentrations between the CR animals and age-matched controls. These data fail to support the hypothesis that CR can attenuate the aging-related decline in plasma DHEAS concentrations, at least not when initiated after puberty.