Synthetic sex hormone treatment during pregnancy and androgen receptors of male offspring.

Groups of 10 pregnant albino rats received a single subcutaneous injection of oil containing synthetic sex hormones on day 13 of pregnancy. Control rats received only oil. The steroid doses were ten times those used as oral hormonal pregnancy tests for humans. Norethisterone acetate (NEA) was given at 2 mg/kg, ethynylestradiol (EE) at 4 micrograms/kg, and NEA + EE together at these same doses. The concentration of penile total specific androgen-receptor binding sites in cytosol preparations was measured by means of in vitro uptake of tritiated methyltrienolone (3H-R 1881). No significant difference was observed between controls and treated groups for androgen-receptor concentrations in preparations from male offspring at birth, or in others reared to day 30. Rat penile androgen receptors showed high affinity for 5 alpha-dihydrotestosterone. Testosterone showed weaker binding (ca. 10%), while R 1881 showed much greater affinity (ca. 550%). Very weak binding was shown by progesterone, estradiol 17 beta, and the synthetic steroids investigated in this study.