ROLE OF CHOLINERGIC AND ADRENERGIC PATHWAYS OF THE MEDIAL SEPTAL AREAIN THE WATER-INTAKE AND PRESSOR-RESPONSE TO CENTRAL ANGIOTENSIN-II AND CARBACHOL IN RATS

In the present study, we investigated the effect of previous injection of either prazosin (alpha 1-adrenergic antagonist) or atropine (musca rinic cholinergic antagonist) into the medial septal area (MSA) on the presser and dipsogenic responses induced by intracerebroventricular ( ICV) injection of carbachol (cholinergic agonist) and angiotensin II ( ANGII) in rats. The presser and dipsogenic responses to ICV carbachol (7 nmol) were reduced after previous treatment of the MSA with atropin e (0.5 to 5 nmol), but not prazosin (20 and 40 nmol). The dipsogenic r esponse to ICV ANGII (25 ng) was reduced after prazosin (40 nmol) into the MSA. The presser response to ICV ANGII was not changed either by previous treatment of the MSA with prazosin or atropine. The present r esults suggest a dissociation among the pathways subserving the contro l of dipsogenic and presser responses to central cholinergic or angiot ensinergic activation.