Corticosteroid transfer from rat fetuses injected with 4-14C-progesterone to acutely and chronically adrenalectomized mothers

On the 22nd day of intrauterine development rat fetuses from mothers adrenalectomized on the 12th and the 22nd day of pregnancy were injected subcutaneously with 16 kBq 4-14C-progesterone. 10 and 20 min following injection the distribution of 4-14C-progesterone metabolites in the plasma of adrenalectomized mothers and the plasma of injected and noninjected fetuses as well as in their adrenal glands were investigated. In the plasma of the injected fetuses radioactive 11-deoxy-corticosterone, corticosterone, 18-hydroxy-11-deoxy-corticosterone, 11β-hydroxy-progesterone, 18-hydroxy-corticosterone and aldosterone were demonstrated. All the steroids crossed the placenta and could be found in smaller amounts in the plasma of chronically and acutely adrenalectomized mothers and in very small amounts in the plasma of their noninjected fetuses. In the plasma of the injected fetuses from chronically adrenalectomized mothers the highest amount of radioactive corticosterone was found. The fetal adrenal glands held smaller amounts of radioactive steroid hormones than the plasma of the noninjected fetuses. These data show that the fetal adrenal glands were the only origin of plasma corticosteroids in the adrenalectomized pregnant rats. The adrenal glands of fetuses from chronically adrenalectomized mothers with their corticosterone participated up to the last day of pregnancy in maintaining the glucocorticoid balance in the chronically adrenalectomized pregnant mothers. (author)