Central serotonergic modulation of drinking behavior induced by water deprivation: effect of a serotonergic agonist (MK-212) administered intracerebroventricularly.

The present study was carried out to evaluate the participation of the serotonergic system (5-HT) in the modulation of the drinking response induced by water deprivation. Male Wistar rats implanted with a cannula in the 3rd ventricle were injected with the 5-HT1C/5-HT2 agonist 6-chloro-2-[1-piperazinyl]-pyrazine (MK-212) at doses of 0.5, 5, 25, 50 and 125 nmol/2 microliters. MK-212 induced a significant reduction (P less than or equal to 0.05) in water intake over a period of 300 min. This result indicates that the central 5-HT system plays an important role, probably at the level of the periventricular hypothalamus, in the modulation of drinking behavior induced by water deprivation.