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 bra in dopamine levels, in rats. Drinking could be initiated in water-repl ete rats by administration of single doses of the dopamine agonist, pe rgolide, the dopamine beta-hydroxylase inhibitor, diethyldithiocarbama te, the alpha-adrenergic antagonist, phenoxybenzamine, or the beta-adr energic agonist. isoproterenol. In each case, the response to these ag ents was reduced or ameliorated by cotreatment with the dopamine antag onist, pimozide. Taken together, the results of the stress and pharmac ological studies support the concept that drinking is initiated by a d opaminergically mediated thirst drive, which in turn is regulated by a noradrenergically mediated satiety system.