Epitestosterone and 5α-Androstane-3α,17βdiol: The Characteristic Metabolites of Androst-4-ene-3,17-dione Produced by Mouse Kidney in Vitro12

Abstract

Mouse kidney homogenate and its subcellular fractions were incubated with [4–14C]— androstenedione (or [4–14C]—testosterone) at pH 6.7 with and without DPNH or TPNH. Epitestosterone was the major metabolite. 5α-Androstane- 3α,17β-diol and testosterone (or androstenedione) were produced in lesser quantities. 17β-Hydroxy- 5α-androstan-3-one, androsterone, epiandrosterone, 5α-androstane-3,17-dione and 5α-androstane-3α, 17β-diol were produced in trace amounts. Trace quantities of 5α-androstane-3α,l7α-diol and 5aandrostane- 3β,17α-diol were indicated as metabolites of androstenedione, but were not conclusively identified. Liver homogenate did not produce epitestosterone from either of the substrates. The reductase activities were localized in the cytosol except that the conversion of androstenedione to testosterone in the DPNH (but not the TPNH) system was localized in the microsomal fraction suggesting separate DPNH- and TPNHspecific 17β-reductase activities. Furthermore, substrate specific DPNH—linked 17β-reductase activities also were suggested. The purified nuclear fraction of the kidney produced a small amount of only testosterone from androstenedione.(Endocrinology92: 72, 1973)