Role of cholinergic and adrenergic pathways of the medial septal area in 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 ( α 1-adrenergic antagonist) or atropine (muscarinic cholinergic antagonist) into the medial septal area (MSA) on the pressor and dipsogenic responses induced by intrace ebroventricular (ICV) injection of carbachol (cholinergic agonist) and angiotensin II (ANGII) in rats. The pressor and dipsogenic responses to ICV carbachol (7 nmol) were reduced after previous treatment of the MSA with atropine (0.5 to 5 nmol), but not prazosin (20 and 40 nmol). The dipsogenic response to ICV ANGII (25 ng) was reduced after prazosin (40 nmol) into the MSA. The pressor response to ICV ANGII was not changed either by previous treatment of the MSA with prazosin or atropine. The present results suggest a dissociation among the pathways subserving the control of dipsogenic and pressor responses to central cholinergic or angiotensinergic activation.