Salt appetite consequent on sodium depletion in the suckling rat pup

Abstract

The ontogeny of the behavioral ability to compensate for sodium deficit was studied in the rat. The experiments showed that: 1) Before weaning age, sodium-depleted pups will increase their avidity for 3% NaCl solution; 2) the ability to select and drink a salt solution in response to a sodium deficit continues to evolve between 17-24 days of age, and that pups at these ages will modify their intake of salt and water as do adult rats when rectifying plasma osmolality; 3) The increased appetite for sodium is evident even when depleted preweanlings are dehydrated and provided with solid NaCl tablets to lick, showing that sodium appetite and hydrational status are already dissociated at this age; and finally, 4) sodium depletion first induces an increase in intake of orally infused 3% NaCl solution in 12-day-old pups. The picture of the development of salt appetite in the suckling rat that these findings present is of a precocious competence to meet a challenge to sodium homeostasis. In this respect salt appetite emerges in parallel to the other ingestive behaviors.

Target-based biomarker selection – Mineralocorticoid receptor-related biomarkers and treatment outcome in major depression

“…Early life conditions, including maternal deprivation, an intense stressor, suppresses hippocampal MR-expression and function in rats (V azquez et al, 1996). Besides behavioral challenges environmental challenges influence MR-related behavior: it appears that sodium depletion in fetal development due to a variety of conditions determines sodium appetite in both animals and humans (Leshem, 2009;Leshem et al, 1993). The exact mechanism of these changes has to be further examined.…”

Ontogeny of urine preference and its relationship to NH4Cl preference and sodium hunger in suckling rat pups

“…Neonatally, sodium hunger also increases intake of other ions and milk until NaCl specificity emerges by some 2 weeks of age; however, unlike urine and NH 4 Cl, none of these tastants or water are preferred to NaCl in sodium-replete or sodium-depleted sucklings (Leshem, 1999;Leshem, del Canho, & Epstein, 1993;, 1989Leshem, Langberg, & Epstein, 1993;Leshem et al, 1994;Sollars & Bernstein, 1994).…”

“…Hence, the preference for urine may guide the pup to its insensible concentration of sodium. Although there is no direct evidence that pups ingest urine in the nest as do dams, thirsty, hungry, or sodiumdepleted pups will lick appropriate fluids (Leshem, 1999;Leshem, Boggan, & Epstein, 1988;Leshem, del Canho, & Epstein, 1993;, 1989Leshem, Langberg, & Epstein, 1993;Leshem et al, 1994;1999;Weller, Smith, & Gibbs, 1990;Wirth & Epstein, 1979).…”

Salt need needs investigation

“…As it develops, the human child increasingly has a predilection for salt, marginally related to early dietary experience (32,92,93) , but significantly related to neonatal hyponatraemia and to growth (16,31,32,(36)(37)(38)(39)(40)88,89) . It is important to note that this increase in later salt appetite occurs with no experience of salt taste, a phenomenon established in rats (2,58,65,66,94) ; in babies, the neonatal Na supplementation is administered intravenously which may not condition a salt preference (95) . In fact, it may be that the consequent increase in dietary Na of such children (aged 10-15 years) is unaccompanied by a preference for the taste of salt per se (37) (but see Liem (89) ), a known dissociation (80,89,96) .…”

“…A very significant and frequently overlooked observation is that animals eat salt (94,140) , whereas humans do not (16) . Surprisingly, the delectability of salt for humans is unrelated to its taste.…”