Vitamin a supplementation transiently increases retinol concentrations in extrahepatic organs of neonatal rats raised under vitamin A-marginal conditions

Abstract

Background: Vitamin A (VA; retinol) supplementation is recommended for children aged > 6 mo in countries with high rates of malnutrition, but the distribution and retention of VA in body tissues have not been extensively explored. Objective: We sought to determine the distribution and retention of VA in tissues of neonatal rats raised under VA-marginal conditions. Methods: Sprague-Dawley neonatal rats (n = 104; 63 males) nursed by mothers fed a VA-marginal diet (0.35 mg retinol equivalents/kg diet) were randomized and treated on postnatal day 4 with an oral dose of either VA (6 mg retinyl palmitate/g body weight) or canola oil as control. Pups (n = 4/group) were killed at 13 time points from 30 min to 24 d after dose administration. The total retinol concentration and mass were determined in all collected organs. Results: In the control group, plasma VA was marginal (0.8 mmol/L), whereas liver VA was deficient (<70 nmol/g). Nonetheless, the liver contained most (;76%) of the total VA mass in the body, whereas extrahepatic nondigestive organs together contained ;13%.White adipose tissue (WAT),which was nearly absent before postnatal day 12, contained only;1%. In VA-supplemented neonates, themean total retinol concentrations in all organswere significantly greater than in control pups. However, this increase lasted for only ;1 d in most extrahepatic tissues, with the exception of WAT, in which it lasted 18 d. Conclusions: Extrahepatic organs in neonatal rats raised under VA-marginal conditions store relatively little VA, and the scarcity of adipose tissue may predispose neonates to a low-VA status. The effect of VA supplementation on VA content in most extrahepatic organs is transient. A more frequent supplementation along with other nutritional interventions may be necessary for maintaining a steady supply of retinol to the rapidly developing extrahepatic organs.