D-1 and D-2 receptor antagonists decrease corn oil sham feeding in rats.

Intraperitoneal injection of the highly selective D-1 and D-2 receptor antagonists, SCH 23390 and (-)-raclopride, respectively, produced a dose-related decrease in the intake of corn oil in a 30-min, sham-feeding test. The threshold dose for a significant decrease in intake was 100 micrograms.kg-1 for SCH 23390 and 200 micrograms.kg-1 for raclopride. These doses did not impair rats' latencies to initiate sham feeding, and they did not produce any overt motor deficits. These data, therefore, are consistent with the hypothesis that central dopaminergic activity at both D-1 and D-2 receptors is necessary for the normal processing of the sensory and/or hedonic effects of the oral stimuli produced by corn oil during sham feeding.