Vitamin A status needed to maintain vitamin A concentrations in nonhepatic tissues of the pregnant rat

Vitamin A-depleted pregnant rats were fed diets containing 0, 1, 10 or 100 retinol equivalents (REq)/d during gestation. Maternal tissues of these dams, their placentas and fetuses were assayed for total vitamin A (retinol and its esters) at gestational ages 10, 13, 16 or 19 d. The vitamin A concentrations in placenta and fetuses of dams fed 10 REq/d were significantly different from those of dams fed no vitamin A. This difference was not seen in any of the six other maternal tissues assayed. We suggest that the fetus is at greater risk than other maternal tissues during severe vitamin A deprivation. For vitamin A-deprived dams, linear regression analysis indicated strong relationships between the vitamin A concentrations of nonhepatic tissues and their liver vitamin A concentrations. In contrast, among vitamin A-replete dams, these relationships were not statistically significant. An estimate was made of the minimal vitamin A status corresponding to tissue repletion by solving linear equations described by the data of the depleted dams for the vitamin A concentrations found in tissues of replete dams. This analysis revealed that a maternal vitamin A status of 3 micrograms/g liver was needed to provide the level of vitamin A found in the placenta, whole fetus and maternal tissues of vitamin A-replete dams.