title: The synthesis of testosterone and estradiol-17beta by the gonads of neonatal rats in vitro.
abstract: The rate of synthesis of estradiol-17beta by the ovary, and of testosterone by the testis of the newborn rat have been studied in vitro using tissue homogenates. Quantitative estimation of these steroids has shown a peak of activity in the ovary between 8 and 12 days post partum of 63 pg/mg tissue/hr, compared with 6 pg/mg/hr at day 6, and 19 pg/mg/hr at day 14. Testosterone synthesis in the testis is most active on day 1 (3.1 ng/mg/hr), declining steadily to 1.1 ng/mg/hr on day 11. Adult testicular tissue under the same conditions synthesised 0.5 - 1.0 ng testosterone/mg/hr. These results are consistent with other observations which have suggested a transient period of active steroidogenesis immediately after birth in the rat, but the time during which steroid synthesis is elevated has been more clearly defined. The methods described here provide a model system for the study of synthetic steroids and other drugs which may affect the sexual differentiation of the hypothalamus by altering gonadal steroidogenesis.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D003687:Dehydroepiandrosterone / Q000378:metabolism; D004958:Estradiol / Q000096:biosynthesis*; D005260:Female; D008297:Male; D010053:Ovary / Q000254:growth & development / Q000378:metabolism*; D051381:Rats; D013737:Testis / Q000254:growth & development / Q000378:metabolism*; D013739:Testosterone / Q000096:biosynthesis*
chemical_list: D013739:Testosterone; D003687:Dehydroepiandrosterone; D004958:Estradiol