THE PROBLEM OF PLACENTAL PERMEABILITY FOR THYROTROPHIN, PROPYLTHIOURACIL AND THYROXINE IN THE GUINEA PIG¹

Abstract

Many investigators have reported that the thyroids are enlarged in offspring from mothers treated with antithyroid agents during pregnancy (mouse—Kaufman, Hurst and Turner, 1948; rat—Hughes, 1944; Goldsmith, Gordon and Charipper, 1945; guinea pig—Albrieux, Estefan and Gonzalez, 1946; Webster and Young, 1948; goat—Schultze and Turner, 1945; man—Davis and Forbes, 1945; Eaton, 1945). This has been taken as evidence for the placental passage of an antithyroid effect The placental passage of the antithyroid effect could occur in one or more of three ways (Goldsmith, Gordon and Charipper, 1945). Thyrotrophin (TSH) from the maternal pituitary might cross the placenta to affect the fetal thyroid. D’Angelo and Gordon (1950) have since shown that administration of propylthiouracil is followed by increased concentration of TSH in the serum. Second, the goitrogen might pass the placenta to inhibit thyroid hormone production in the fetus. This would lead to stimulation of the fetal thyroid by TSH secreted by its own pituitary.