Effects of haloperidol on schedule-induced polydipsia.

In dose-related amounts, the drug haloperidol attenuated schedule-induced drinking by rats prefed with 0.01-mg drug added to 0, 25, 50, 75 or all of 100 Noyes 45-mg pellets. Drug pellets also induced less drinking than did regular Noyes pellets by rats that obtained these pellets at 1-min intervals by bar pressing. Haloperidol also reduced bar pressing and, temporarily, rate of reinforcement. The results appeared not to be due to a general sedative effect of haloperidol but to its selective power to reduce angiotensin-induced drinking. Thus, schedule-induced drinking, which is abnormal in not causing satiation, is controllable by a drug that interferes with the renin-angiotensin hormone system thought to regulate normal drinking.