Vitamin A and retinol-binding protein metabolism during fetal development in the rat.
Studies were conducted on the metabolism and placental transport of vitamin A and plasma retinol-binding protein (RBP) during fetal development in the rat. Vitamin A accumulated in the conceptus in three phases: an early phase (days 7-9 of gestation) characterized by a high vitamin A concentration; a second phase (days 11-14) where vitamin A and RBP accumulated in parallel; and a third phase of continued vitamin A and RBP accumulation (days 16-20) in which vitamin A was stored in the fetal liver. The early phase of vitamin A accumulation may reflect a mechanism that exists to prepare the conceptus to meet the presumably higher vitamin A requirements of the critical period (days 10-14) of organ differentiation. Fetuses and placentas from retinol-deficient dams showed low levels of RBP through days 16-18 of gestation. A retinol-repletion study suggested, moreover, that the maternal retinol-RBP complex crossed the placenta. The various studies all suggest that vitamin A is transported from dam to fetus, from and after day 11, mainly by transplacental transport of maternal retinol-RBP. Finally, evidence was obtained indicating that the fetal liver begins to synthesize RBP around the 16th day of gestation and that by the 20th day, the fetal liver has a considerable capacity for RBP synthesis.
D000818:Animals; D005260:Female; D005333:Fetus / Q000378:metabolism*; D005865:Gestational Age; D008099:Liver / Q000378:metabolism; D008431:Maternal-Fetal Exchange; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D051381:Rats; D012177:Retinol-Binding Proteins / Q000378:metabolism*; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000378:metabolism*
D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A