Formation of Dihydrotestosterone and Other 5α-Reduced Metabolites by Isolated Seminiferous Tubules and Suspension of Interstitial Cells in a Human Testis

ABSTRACT

Interstitial cells were separated from seminiferous tubules in a testis from a 17-yr-old male by treatment of tissue with collagenase. The separated compartments were incubated with ³H-androstenedione and a NADPH generating system. The various products were isolated, identified and the amounts produced following a 2-hr incubation were compared in the separated tissue compartments. The conversion to testosterone was approximately the same in the 2 compartments. Seminiferous tubules effected a much greater conversion to Sa-reduced metabolites than did the interstitial cell suspension. The ratio of Sa-reduced steroids in tubules to that in interstitial cell suspension was 50 to 1. Only seminiferous tubules synthesized dihydrotestosterone, while androsterone was only identified in the interstitial cell incubation. Both 5α-androstane-3β,17β-diol and 5α-androstane-3α,17β-diol were found in equal amounts in seminiferous tubules (7% total conversion from androstenedione). The androstanediols were found only in minute quantities in the interstitial cell suspension (0.13%). The ratio of the extent of cleavage of ³H-pregnenolone sulfate in seminiferous tubules compared to the interstitial cell suspension in a 2-hr incubation was 61%: 6.9%. The data suggest that dihydrotestosterone may be the mediator of androgen action in human seminiferous tubules.