Antidipsogenic action of alpha-human atrial natriuretic polypeptide administered intracerebroventricularly in rats

Intracerebroventricular (i.c.v.) administration of alpha-human atrial natriuretic polypeptide (alpha-hANP) in a dose of 5 micrograms did not change water intake in normal rats, while 0.1 micrograms of angiotensin II (AII) and 0.5 micrograms of carbachol caused a marked increase in water intake for 30 min after i.c.v. injections. The water intake induced by 0.1 micrograms of AII was significantly suppressed by the simultaneous administration of 2 and 5 micrograms of alpha-hANP. However, alpha-hANP did not affect the water intake caused by 0.5 micrograms of carbachol. In 24-h water-deprived rats, alpha-hANP in doses of 2 and 5 micrograms pronouncedly inhibited the water intake. alpha-hANP did not change the food intake in 24-h fasted rats nor the locomotor activity in normal rats. These findings suggest that alpha-hANP in the central nervous system may play an important role in controlling drinking behavior, interacting with AII.