Effect of prostaglandin E1 and its biosynthesis inhibitor indomethacin on drinking in the rat

In the rat, injection of prostaglandin E1 (PGE1) 0.5, 1.0 or 2.0 microgram into the 3rd brain ventricle (3rd b.v.) inhibited the water deprivation-induced water intake in a dose-related fashion. The 1.0 microgram dose of PGE1 also inhibited the intake of 1.8% sodium chloride in rats depleted of body sodium by intraperitoneal dialysis, and of food in food deprived rats during a 60 min test period. Prostaglandin E1 (1 microgram) depressed the dipsogenic effect of angiotensin II (AII) or carbachol injected through the same cannula. Water-deprived rats pretreated with the PG synthetase inhibitor indomethacin, in two different doses, showed enhanced water intake. The pretreatment with indomethacin also enhanced the dipsogenic effect of various doses of AII injected into the 3rd b.v. The antagonistic action of PGE1 on water-deprivation, or AII-induced water intake, and the enhancement of water intake after blocking PGs synthesis, suggests the involvement of PG in the regulation of thirst.