Dopamine antagonists act on central, but not peripheral, receptors to inhibit sham and real feeding

We examined the relative contribution of dopamine (DA) receptors in the brain and periphery in the control of sham and real feeding of sucrose solutions. Intraperitoneal (IP) administration of pimozide, an antagonist of peripheral and brain DA receptors, suppressed both sham and real feeding in a dose-related manner. In contrast, IP injections of domperidone, a DA antagonist restricted to peripheral receptors, had no effect on either sham or real feeding. The inability of domperidone to influence sucrose intake did not result from a lack of biological activity of the drug because the identical doses of domperidone that failed to alter eating significantly inhibited gastric acid secretion. The results implicate central, but not peripheral, DA receptors in the control of the ingestion of palatable foods and also suggest that sham feeding is more sensitive to DA antagonism than real feeding.