Metabolism of Progesterone by Rat Testicular Homogenates. I. Isolation and Identification of Metabolites

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Abstract
Homogenates of rat testicular tissue have been incubated with progesterone 4-C14 and certain of the metabolites have been identified. When small ratios of substrate to tissue were used, there was usually a large conversion to testosterone-Cl4 (30-35%). Much smaller amounts of [DELTA] 4-andro-stene-3,17-dione and 17-hydroxy-[DELTA]4-pregnene-3,20-dione were found. Labeled 16[alpha]-hydroxy-[ALPHA]4 -pregnene-3,20-dione and 17,20[alpha]-dihydroxy-[DELTA]4-pregnen-3-one were produced in small yields. Substantial conversions (8-40%) to 5a-androstane-3[alpha], 17[BETA]-diol were found. These results indicate that testosterone is the principal androgen produced in rat testicular homogenates, and that, at least in vitro, the rat testis further metabolizes significant amounts of testosterone by reduction in ring A.