Interactive dopaminergic and noradrenergic systems in the regulation of thirst in the rat.

Twenty-three hours of fluid deprivation led to elevated plasma levels of corticosterone and free fatty acids, as well as increased whole brain dopamine levels, in rats. Drinking could be initiated in water-replete rats by administration of single doses of the dopamine agonist, pergolide, the dopamine beta-hydroxylase inhibitor, diethyldithiocarbamate, the alpha-adrenergic antagonist, phenoxybenzamine, or the beta-adrenergic agonist, isoproterenol. In each case, the response to these agents was reduced or ameliorated by cotreatment with the dopamine antagonist, pimozide. Taken together, the results of the stress and pharmacological studies support the concept that drinking is initiated by a dopaminergically mediated thirst drive, which in turn is regulated by a noradrenergically mediated satiety system.