Intracerebroventricular (i.c.v.) administration of JA116a, induces an increase in urinary volume and sodium excretion in conscious male hydrated rats. The involvement of brain dopaminergic neurons in the JA116a renal action was investigated. Diuretic and natriuretic action of JA116a was blocked by haloperidol pretreatment. The renal effect was prevented by selective dopaminergic neuron, denervation by i.c.v. administration of 6-hydroxydopamine in combination with desmethylimipramine. Our results suggest that JA116a acts centrally, at least in part, via an interaction with endogenous dopamine neurons.