<i>In Vitro</i>Metabolism of Steroid Hormones by Cell-Free Homogenates of Epididymides of Adult Rats

Abstract

When pregnenolone-4-14C was incubated at 37 C for 1 hr with the cell-free homogenates of the epididymides obtained from adult rats, the substrate was recovered without any appreciable conversion. But, after incubation of progesterone-4-14C with the epididymis homogenates, 5α-pregnanedione was obtained as the major metabolite from progesterone, and 3αhydroxy- 5α-pregnan-20-one as a minor metabolite. On the other hand, 17α-hydroxy-5αpregnane-3,20-dione, 3α,17α-dihydroxy-5α-pregnan- 20-one and 17α,20α-dihydroxypregn- 4-en-3-one were obtained as the metabolites of 17α-hydroxy progesterone by the epididymal homogenate. 5α-Androstanedione and androsterone were identified as the metabolites of androstenedione. After incubation with 14C-labeled testosterone, 17β-hydroxy-5α-androstan-3-one was obtained as the major metabolite, but 5α-androstane-3α,17β-diol was present in very small amount. The enzyme pattern in the epididymis of adult rat was characterized by the significant activities of the Δ4-5α-hydrogenase and 3α-hydroxysteroid dehydrogenase which worked upon both C19 and C21 steroids. (Endocrinology84: 997, 1969)