Ontogenic expression of retinoid homeostatic genes in principal vitamin A storage organs

Abstract

Vitamin A (VA) is essential for proper lung development in early life. The combination of VA and 10% all‐trans retinoic acid (VARA) works synergistically to increase total retinyl ester storage and retinol uptake in neonatal rat lung. To confirm the necessity of VA for lung maturation and septation, VA metabolism during neonatal development must be understood. In the present study, we determined the effects of VA nutritional status and VARA supplementation during ontogeny on expression of retinoid homeostatic genes. Rat dams and their post‐weaning offspring were fed a VA‐marginal or supplemented diet, while pups received an oral dose of oil (placebo) or VARA on post‐natal day (P) P0/1, P4, P7, and P10. Tissues were collected 6 hr later. Gene expression was determined by qRT‐PCR in liver, lung, and kidney. VA‐supplemented diet and VARA treatment upregulated LRAT, Cyp26A1/B1, and STRA6, retinoid homeostatic genes important for VA storage, RA terminal oxidation, and retinol uptake, respectively. However, VARA did not regulate VA trafficking genes (RBP in liver and megalin in kidney). Cyp26a1 expression in liver decreased throughout development in rats fed marginal diet, but increased on the supplemented diet. No apparent difference was observed in RALDH1/2/3 expression with VARA treatment. Our results advance the understanding of neonatal VA metabolism and catabolism in principal VA storage organs.Grant Funding Source: NIH HD006892