Effects of dopamine antagonists on fluid intake and salt preference in male and female rats

The effects of three dopamine antagonists (pimozide, clozapine, sulpiride) on fluid consumption by water-deprived rats trained to choose between a saline solution and water in a 15 min drinking test were examined. Rats of each sex were allocated to three groups and given access to 0.125% NaCl, 0.6% NaCl, and 1.7% NaCl, respectively, as the alternative to water. Dose-dependent reductions in fluid consumption were produced by pimozide (0.1- 3.0 mg kg(-1)) and clozapine (0.3-10.0 mg kg(-1)), but not by sulpiride (1.0-30 mg kg(-1)). There were instances of a hyperdipsic effect of sulpiride. The dopamine antagonists produced significant changes in saline preference, but in no case was a decrease in preference detected. Instead, there was evidence for induction of preference, or enhancement of preference, in both sexes. So far as determinants of preference for the salt are concerned, it appears that in the rat, dopamine may have a predominantly inhibitory action.