Biology of Reproduction, Vol 25, 93-102, Copyright © 1981 by Society for the Study of Reproduction

Effect of Medroxyprogesterone Acetate on 3-Hydroxysteroid Oxidoreductase of Testicular Germ Cells and Prostate of the Rat

¹ Department of Biology, Biological Science Center, Boston University, Boston, Massachusetts 02215

On incubation with testosterone (T), nonflagellate germ cells of rat testis produced dihydrotestosterone (DHT) and 5-androstane-3, 17-diol (3-diol). When the concentration of T was adjusted to 0.1 µM (its level in rete testis fluid), 4-androstene-3, 17-dione (A) and DHT accumulated during the first 30 min; during the subsequent 90 min, A declined and 3-diol accumulated, DHT remaining at almost constant level. Medroxyprogesterone acetate (MPA, 5 µM) abolished 3-diol production, but allowed DHT to accumulate at linear rates. Separation of nonflagellate germ cells by velocity gradient sedimentation yielded spermatocytes and spermatids as major fractions. On incubation with 0.1 µM T, the spermatocytes produced A and DHT; the spermatids, although metabolizing T at lower rates, produced relatively large amounts of 3-diol. In the presence of T in physiological concentration, MPA did not inhibit 5-reductase or 17-hydroxysteroid oxidoreductase of germ cells. It abolished 3-diol formation in the spermatids, allowing DHT to accumulate in equivalent amounts. The action of MPA as a specific inhibitor of 3-hydroxysteroid oxidoreductase without effect on 5-reductase was also observed in rat prostate extracts when these were incubated with 0.1 µM T.