D-2 RECEPTORS IN THE VENTROLATERAL STRIATUM ARE INVOLVED IN FEEDING-BEHAVIOR IN RATS

To study the role of dopamine D-1 and D-2 receptors in the ventrolateral striatum in feeding behavior, a D-1 receptor agonist (CY 208-243), a D-1 receptor antagonist (SCH 23390), a D-2 receptor agonist (quinpirole), and a D-2 receptor antagonist [(-)-sulpiride] were perfused via a microdialysis probe into the ventrolateral striatum of rats fasted for 22 h. Then the rats were allowed to feed freely for 6 h. Sulpiride perfusion at a high concentration suppressed food and water intake significantly, whereas dopamine release and the levels of DOPAC and HVA were increased at all concentrations. In contrast, quinpirole perfusion at a high concentration increased food intake by 41%. Dopamine release and the levels of DOPAC and HVA were decreased at all concentrations. On the other hand, neither CY 208-243 nor SCH 23390 changed food intake or dopamine release, but both drugs decreased water intake. These results suggest that D-2 receptors in the ventrolateral striatum have a more important role than D-1 receptors in the feeding behavior of rats.