Hydroxylation of testosterone in the human testis. Identification of 4-androstene, 7 alpha,17 beta-diol-3-one (7 alpha-hydroxytestosterone) as a metabolite of testosterone.

Homogenates of normal or cryptorchid, human testes were incubated with [3H]testosterone and a NADPH-generating system. [3H]4-andostene,7 alpha,17 beta-diol-3-one (7 alpha-OH-testosterone) was isolated and identified from such incubations. To our knowledge this is the first demonstration that 7 alpha-OH-testosterone is a metabolite of testosterone in the human testis. 4-Andro-stene,6 beta,17 beta-diol-3-one (6 beta-OH-testosterone) and 4-androstene,16 alpha,17 beta-diol-3-one (16 alpha-OH-testosterone) were also identified as testosterone metabolites. The specific activity of both testosterone 6 beta- and 16 alpha-hydroxylase was higher than that of 7 alpha-hydroxylase. Pre-pubertal or cryptorchid human testis tissues seem in our study to have higher testosterone 6 beta- and 7 alpha-hydroxylase activity than normal adult testis tissue.