Effects of dopamine receptor antagonists on sucrose consumption and preference.

Effects of the dopamine D2 receptor antagonist sulpiride and the D1 antagonist SCH-23390 were examined, in rats, in two-bottle preference tests (sucrose versus water) and in single-bottle tests, at different sucrose concentrations. Both drugs decreased sucrose intake in single bottle tests, at low sucrose concentrations, but had no effect at high concentrations; reducing drive level had exactly the opposite pattern of effects. In two-bottle tests, both drugs reduced preference for the weakest sucrose concentration (0.7%) but increased preference for the strongest concentration (34%). The effects of antagonizing either subtype of DA receptor appear to be similar to those of reducing the concentration of sucrose.