Steroid Metabolic Pathways in Feminizing Testicular Tissue

Feminizing testicular tissue was homogenized and incubated with a variety of labeled steroids as substrates. Analysis of the products obtained suggest that in this tissue steroids were metabolized primarily by the Δ5-pregnenolone pathway rather than by the Δ4-progesterone pathway. No labeled estrogens could be isolated from these incubations. The 3β-hydroxysteroid dehydrogenase system in this tissue was much less active than that in the normal testis. Among the products of progesterone were androst-4-ene-3,17-dione, 20α-hydroxypregn-4-en-3-one, 17-hydroxyprogesterone, 16-hydroxyprogesterone, and testosterone. Incubation with pregnenolone gave dehydroepian-drosterone, androst-4-ene-3,17-dione, 17-hydroxyprogesterone, 17-hydroxypregnenolone, testosterone, progesterone, and androst-5-ene-3,17-diol. Incubations with dehydroepiandrosterone gave testosterone, androst-4-ene-3,17-dione and androst-5-ene-3,17-diol as products. Kinetic experiments with dehydroepiandrosterone as substrate suggest that dehydroepiandrosterone and androstenedione are metabolized at a considerable rate, whereas androstenediol and testosterone are not metabolized further.