Localization and identification of nuclear radioactivity in the pituitary gland and genital tract after administering 3H-testosterone, 3H-dihydrotestosterone, or 3H-estradiol to male rhesus monkeys.

Target cells for testosterone, dihydrotestosterone, and estradiol in the pituitary gland and genital tract of the male primate were localized by thaw-mount autoradiography, and high performance liquid chromatography was used to identify the metabolites of these steroids in cell nuclei. Castrated rhesus monkeys were injected with 3H-testosterone, 3H-dihydrotestosterone, or 3H-estradiol and killed 60 min later. In the anterior pituitary gland, fewer cells were labeled and less radioactivity was taken up by cell nuclei following the administration of either 3H-testosterone (4% of pars distalis cells and 5 dpm/micrograms DNA) or 3H-dihydrotestosterone (5% of cells and 13 dpm/micrograms DNA) than following the administration of 3H-estradiol (43% of cells and 214 dpm/micrograms DNA). Most of the radioactivity in nuclei was in the form of the unmetabolized parent compound (78-94%). In prostate, seminal vesicles, and penis, 3H-dihydrotestosterone was the predominant form of nuclear radioactivity following both 3H-testosterone (67-90%) and 3H-dihydrostestosterone (94-97%) administration, and both androgens labeled epithelial and smooth muscle cells. In contrast, 3H-estradiol was taken up in unchanged form, by cell nuclei of the genital tract and it labeled connective tissue fibroblasts, but not epithelial cells. Thus, the distributions of target cells for androgens and estrogens were clearly different in all these tissues, and the uptake of testosterone resembled that of its androgenic rather than that of its estrogenic metabolite.