SODIUM DEPLETION AND MATERNAL SEPARATION IN THE SUCKLING RAT INCREASEITS SALT INTAKE WHEN ADULT

To establish whether neonatal sodium depletion increases the adult's a vidity for NaCl, 12-day-old suckling pups were injected with the natri uretic-diuretic furosemide (1 mg) while with their dams. The injection s surged plasma aldosterone, and when the rats were adult (70 days), t heir spontaneous intake of 3% NaCl was increased. Additional experimen ts investigated whether maternal separation has a similar effect and c ould thus be a source of individual variation in salt intake of the ad ult. Fifteen-day-old pups were separated from their dams for 24 h in a n incubator. When adult, their intake of 3% NaCl was increased. Availa bility of saline during maternal separation obviated the effect. The i ncrease in adult intake of 3% NaCl was specific insofar as drinking of water was not increased similarly. The results show that the adult ra t's avidity for sodium can be increased by postnatal natriuresis and p ossibly stress. The implications of the findings are discussed.