Central serotonergic modulation of drinking behavior induced by angiotensin II and carbachol in normally hydrated rats: effect of intracerebroventricular injection of MK-212

ABSTRACT

The objective of the present study was to evaluate the role of the central erotonergic (5-HT) system in the modulation of drinking behavior induced angiotensin II (Ang II) and carbachol. Male Wistar rats implanted with a delay cannula in the 3 rd ventricle were injected with the 5-HT1C/5-HT2 agonist 6-chloro-2-[1-piperazinyl]-pyrazine (MK-212) (50 nmol/2 µl) before receiving an intracerebro-ventricular (icv) injection of Ang II or carbachol (100 ng/2 µl). MK-212 induced a significant reduction in the drinking response evoked by Ang II or carbachol which was more marked in the case of the cholinergic agonist. The results obtained suggest that thirst and water intake produced by angiotensinergic or cholinergic activation are modulated by the action of 5-HT, possibly at the level of the periventricular hypothalamus