Schedule-induced polydipsia suppresses pituitary-adrenal activity in rats.

The effects of schedule-induced polydipsia (SIP) on pituitary-adrenal activity, as indicated by plasma levels of corticosterone, were examined in 3 experiments in which a total of 52 Sprague-Dawley rats were given daily sessions on a fixed time 60-sec intermittent-feeding schedule. Half of the Ss in each experiment had water available during sessions. Ss with water available in the experimental chamber exhibited SIP. Blood samples were taken at various steps in the procedure and also after the opportunity to drink during sessions was removed. Results indicate that (a) schedule-induced drinking suppresses pituitary-adrenal activity, (b) corticoid suppression may become a conditioned response to drinking in the chamber, and (c) corticoids return to presession levels following removal of water from the chamber. In view of these findings, it is hypothesized that SIP may serve an arousal-reducing role in intermittent-feeding situations. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)