Effect of third ventricle administration of L-694,247, a selective 5-HT1(D) receptor agonist, on water intake in rats

L-694,247, a selective 5-HT1(D) receptor agonist, injected directly into the third ventricle (2.5, 5.0, and 10.0 mu g/rat) of dehydrated rats induced a dose-dependent partial blockade of water intake. Injected in this way, the compound abolishes drinking behavior induced by third ventricle administration of carbachol (2 mu g/rat), angiotensin II (5 mu g/rat), and isoproterenol (40 mu g/rat). In addition, intraventricular injections of L-694,247 did not modify water intake in normohydrated rats. The effects of L-694,247 are due to a specific interaction with 5-HT1(D) receptors, because its inhibitory effect on water intake in dehydrated rats is blocked by the previous administration of a 5-HT1(D) antagonist, GR 127935 (5 mu g/rat), directly into the third ventricle. It is concluded that central 5-HT1(D) receptor activation disrupts the functional integrity of central pathways related to drinking behavior. (C) 1997 Elsevier Science Inc.