Interrelationships between tissue iron status and erythropoiesis during postweaning development following neonatal iron deficiency in rats.

Dietary iron is particularly critical during periods of rapid growth such as in neonatal development. Human and rodent studies have indicated that iron deficiency or excess during this critical stage of development can have significant long- and short-term consequences. Since the requirement for iron changes during development, the availability of adequate iron is critical for the differentiation and maturation of individual organs participating in iron homeostasis. We have examined in rats the effects of dietary iron supplement following neonatal iron deficiency on tissue iron status in relation to erythropoietic ability during 16 wk of postweaning development. This physiological model indicates that postweaning iron-adequate diet following neonatal iron deficiency adversely affects erythroid differentiation in the bone marrow and promotes splenic erythropoiesis leading to splenomegaly and erythrocytosis. This altered physiology of iron homeostasis during postweaning development is also reflected in the inability to maintain liver and spleen iron concentrations and the altered expression of iron regulatory proteins in the liver. These studies provide critical insights into the consequences of neonatal iron deficiency and the dietary iron-induced cellular signals affecting iron homeostasis during early development.