Vitamin A supplementation promotes the uptake and tissue storage of vitamin A in a kinetic study of neonatal rats (645.21)

Abstract

Previous studies conducted in our laboratory have shown that supplementing neonatal rats with a combination of vitamin A (VA) and retinoic acid increases total retinol (ROH) concentration in plasma, liver and lung. The objective of the present study was to examine the effect of VA supplementation, in the absence of retinoic acid, on the metabolism and kinetics of total ROH in plasma and liver of neonatal rats. On postnatal d 4, pups (n = 103) received an oral dose of either VA (6 μg of retinyl palmitate/g of body weight) or canola oil, both containing 2.5 μCi of [3H]retinol acting as the tracer. Subsequently, pups (n = 4/group/time) were euthanized at 13 time‐points from 30 min to 24 d after dose administration. VA supplementation transiently increased total ROH concentration in plasma, due mainly to an elevation of retinyl esters, which disappeared 15 h after dosing. In the liver, total ROH concentration remained significantly elevated in the VA group until d 18 after dosing. VA also increased the amount of [3H]retinol present in the liver from d 8 to d 12 and enhanced the clearance of [3H]retinol from plasma on d 1 following dose administration. The results indicate that VA supplementation may stimulate the uptake of VA by the liver for storage during the neonatal period.Grant Funding Source: NIH HD‐066982