Schedule-induced water and saccharin polydipsia under haloperidol

Abstract

Two white rats exhibited water and.4% saccharin polydipsia under a fixed-time 1-min feeding schedule. Oral administration of haloperidol in doses of.25,.50, and.75 mg reduced consumption of both fluids in direct proportion to dose, but saccharin intakes always exceeded those of water. Thus, the suppression of water polydipsia by haloperidol (Keehn, Coulson, & Klieb, 1976) is not merely the result of sedation. We argue that polydipsia occurs because food plus fluid is a greater reinforcer than food alone and that excessive drinking is a side effect of a normal reinforcement process that overpowers homeostatic mechanisms; the effect of haloperidol is to redress this imbalance.