ROLE OF THE ADRENERGIC PATHWAYS OF THE LATERAL HYPOTHALAMUS ON WATER-INTAKE AND PRESSER RESPONSE INDUCED BY THE CHOLINERGIC ACTIVATION OF THE MEDIAL SEPTAL AREA IN RATS

In the present experiments, we investigated a possible involvement of noradrenergic receptors of the lateral hypothalamus (LH) in the water intake and presser response induced by cholinergic stimulation of the medial septal area (MSA) in rats. The cholinergic agonist carbachol (2 nmol) injected into the MSA induced water intake and presser response . The injection of an alpha(2)-adrenergic agonist, clonidine (20 and 4 0 nmol), but not of an alpha(1)-adrenergic agonist, phenylephrine (80 and 160 nmol), into the LH inhibits the water intake induced by carbac hol injected into the MSA. The injection of clonidine or phenylephrine into the LH produced no change in the MAP increase induced by carbach ol injected into the MSA. The present results suggest that adrenergic pathways involving the LH are important for the water intake: but not for the presser response, induced by cholinergic activation of the MSA .