Brain serotoninergic stimulation reduces the water intake induced by systemic and central beta-adrenergic administration.
1. This study was undertaken to determine if the stimulation of central serotoninergic receptors affects the thirst-inducing action of systemically or intracerebroventricularly (icv) injected isoproterenol. 2. Male Wistar rats weighing 220-300 g were used in groups of 10-14 animals each. Normally hydrated rats implanted with a delay cannula into the third ventricle were injected icv with the 5HT1C/5HT2 agonist MK212 (50 nmol/2 microliters) prior to administration of isoproterenol sc (330 micrograms/kg body weight) or icv (10 and 25 and 50 micrograms/2 microliters). 3. Icv injections of MK212 reduced the water intake induced by isoproterenol injected systemically (56%) and by the two lowest doses of isoproterenol injected icv (76 and 86%, respectively). 4. The results suggest that the central serotoninergic system modulates the central beta-adrenergic system involved in water intake. 5. Taken together with previous results showing that the activation of 5HT1C/5HT2 receptors promotes a reduction of the dipsogenic response evoked by water deprivation or by icv injection of angiotensin II or carbachol, the present data suggest that the central serotoninergic system plays a ubiquitous role in the modulation of water intake behavior.
Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil.
L C
LC
Reis
M J
MJ
Ramalho
J
J
Antunes-Rodrigues
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage*; D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000187:drug effects*; D004326:Drinking / Q000187:drug effects*; D007545:Isoproterenol / Q000008:administration & dosage; D008297:Male; D011719:Pyrazines / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects*; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage; D013268:Stimulation, Chemical; D013997:Time Factors
D000318:Adrenergic beta-Agonists; D011719:Pyrazines; D011985:Receptors, Serotonin; D017366:Serotonin Receptor Agonists; C014896:6-chloro-2-(1-piperazinyl)pyrazine; D007545:Isoproterenol