Neuroleptic-induced deficits in food and water regulation: similarities to the lateral hypothalamic syndrome.

The role of central dopaminergic mechanisms in the regulation of food and water intake was assessed by examining the effects of haloperidol and pimozide on various measures of feeding and drinking in rats. Haloperidol (0.20 mg/kg) or pimozide (0.45 mg/kg) did not significantly affect 1-hr water intake in response to 24 hrs of water deprivation, nor did they influence 2-hr food intake after 24 hrs food deprivation. However both pimozide and haloperidol significantly reduced drinking in response to injections of hypertonic saline. In addition, animals pretreated with these drugs drank less than controls in the absence of food (a measure of "non-prandial" drinking), and drank less than controls when the water was adulterated with quinine (a measure of "finickiness"). These drugs also significantly reduced food intake in response to injections of insulin and attenuated amphetamine anorexia. These deficits are similar to those observed after electrolytic lesions of the lateral hypothalamus or after 6-hydroxydopamine lesions of the substantia nigra. Because haloperidol and pimozide block central dopaminergic receptor sites, the present findings are consistent with the hypothesis that part of the lateral hypothalamic syndrome is the result of damage to the dopaminergic nigro-neostriatal projection. Finally, the data suggest that the changes in feeding and drinking induced by haloperidol and pimozide reflect genuine homeostatic deficits rather than being due to a neuroleptic-induced motor dysfunction.