Development of angiotensin-induced drinking in the rat

The suckling rat responds from birth to intraventricular angiotensin, and the drinking behavior elicited by the hormone achieves adult characteristics of reliability and sensitivity at 4--5 days of age. Additional testing of 5-day-old rats injected with a range of doses showed that the threshold dose lies between 0.1--1.0 ng, which is comparable to the adult sensitivity to intraventricular injections. The hormone also increases milk intake in neonates, but the animals choose water over milk as early as 17 days.