Vitamin A Supplementation Increases the Uptake of Chylomicron Retinyl Esters into the Brain of Neonatal Rats Raised under Vitamin A-Marginal Conditions

卷:146

Hodges, Joanna K. ; Tan, Libo ; Green, Michael H. ; Rosso, A. Catharine

Penn State Univ

关键词: brain;    chylomicron;    neonate;    rat;    retinol;    retinyl esters;    supplementation;    uptake;    vitamin A;   

DOI  :  10.3945/jn.116.233692

学科分类：食品科学和技术

【 摘 要 】

Background: The most rapid phase of brain development occurs during the neonatal period. Vitamin A (VA; retinol) is critical for many aspects of this process, including neurogenesis, synaptic plasticity, learning, and memory formation. However, the metabolism of retinol in the neonatal brain has not been extensively explored. Objective: We examined the uptake of VA into the brain in neonatal rats raised under VA-marginal conditions (control group) and assessed the effect of VA supplementation on the uptake of VA into the brain. Methods: Sprague-Dawley neonatal rats (n = 104) nursed by mothers fed a VA-marginal diet were randomly assigned and treated on postnatal day 4 with an oral dose of either VA (6 mu g retinyl palmitate/g body weight) or canola oil as the control, both of which contained 1.8 mu Ci [H-3]retinol. Pups (n = 4/group at a time) were killed at 13 sampling times from 30 min to 24 d after dosing. The uptake of total retinol, chylomicron-associated retinyl esters (REs), and retinol bound to retinol-binding protein (RBP) was estimated with the use of WinSAAM version 3.0.8. Results: Total retinol mass in the brain was closely dependent on its mass in plasma over time (r = 0.91, P < 0.001). The uptake of retinol into the brain involved both postprandial chylomicrons and RBP, with RBP delivering most of the retinol in the control group [0.27 nmol/d (RBP) compared with 0.01 nmol/d (chylomicrons)]. VA supplementation increased the fractional uptake of chylomicron REs from 0.3% to 1.2% of plasma pool/d, decreased that of RBP retinol from 0.5% to 0.2% of plasma pool/d, and increased the transfer rate of chylomicron REs from nearly zero to 0.7 nmol/d, causing a day-long elevation in the brain mass of total retinol. Conclusion: Postprandial chylomicrons may be a primary mechanism for delivering a recently ingested large dose of VA to the brain of neonatal rats raised under VA-marginal conditions.