Interconversions of Steroids by Intact Bovine Sperm and Epididymal Tissue1

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Abstract
Dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, androsterone, 3α-androstanediol, etiocholoanolone and 3α-etiocholanediol were used as substrates to determine the potential of intact bovine testicular and ejaculated sperm and of epididymal tissue to interconvert androgens by oxidation-reduction of carbon-carbon and carbon-oxygen bonds such as C4-5, C5-6, C3 and C17. Few qualitative differences in the steroid interconverting enzyme systems were found between testicular and ejaculated sperm. Sperm contain C3 and C17-hydroxysteroid oxidoreductases and probably both sperm cell types contain a Δ4-3-ketosteroid 5α-oxidoreductase active on androstenedione. However, the parallel conversion of testosterone to dihydrotestosterone or other 5α-reduced androgens was not detected. Epididymal tissue incubated in vitro readily converted testosterone to dihydrotestosterone and other 5α-reduced metabolites.