Fetal and Maternal Vitamin A Levels in Tissues of Hypervitaminotic A Rats and Rabbits

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Abstract
Pregnant rats and rabbits were given excess vitamin A, in the form of retinyl acetate or retinoic acid, for the 3-day period just prior to palatal closure in the fetuses. Twenty-four hours later, the various forms of vitamin A, and their levels, were determined in fetal liver and carcass and in maternal liver and serum by thin-layer chromatography. The predominant forms of vitamin A found in both fetal and maternal tissues were retinyl palmitate, retinol and retinoic acid. In both species, the tissues from the groups treated with retinoic acid contained levels of vitamin A similar to those found in control tissues. After retinyl acetate treatment in the rat, both of the maternal tissues studied had elevated vitamin A levels, whereas in the rabbit only maternal liver levels increased. In the groups treated with retinyl acetate, the ratio of the vitamin A levels in fetal liver:maternal serum reflected a species difference: the ratio was lower than the control value in the rabbit and higher than controls in the rat. Radiotracer studies in the rat, using either 3H-retinol or 14C-retinoic acid, demonstrated vitamin A transport across the placenta, with vitamin A concentrating in the fetal liver.