title: 5 alpha-reductase activity in stroma and epithelium of rat prostate and epididymis. A contribution to elucidation of the mechanism for development of hyperplastic growth of prostatic tissue.
abstract: The 5 alpha-reductase activity was assayed in homogenates of stroma and epithelium in the rat ventral prostate and epididymis. Samples consisting of a 0.3 mg/ml tissue protein in TES buffer, pH 7.0 were incubated at 37 degrees C for 30 min in the presence of 50 nM [1,2-3H]testosterone and a NADPH-generating system started with 5 x 10(-4) M NADP. The yield of 5 alpha-reduced metabolites, as established by using thin-layer chromatography, gave an estimate of enzyme activity. Whereas the specific activity of 5 alpha-reductase was highest in prostatic stroma and epididymal epithelium, most of the total enzyme activity was associated with the epithelium in both the prostate and epididymis. The effect of dihydrotestosterone on specific activity of 5 alpha-reductase was studied by administering the hormone to 7-day castrated rats. In prostate, the specific activity of both stromal and epithelium forms of the enzyme reached a maximum after 4 days of treatment. In epididymis only the epithelial form of 5 alpha-reductase underwent a major change in specific activity, the latter peaking after 8-12 days of treatment. Furthermore, while the total activity of 5 alpha-reductase in the prostatic tissue fractions could be induced by as much as 4-fold the normal control values, the epididymal enzyme could not be induced above the normal level either in the stroma or the epithelium. This may explain the relative resistance of epididymis to abnormal growth stimulation under the influence of hormones.
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism*; D000818:Animals; D002855:Chromatography, Thin Layer; D013196:Dihydrotestosterone / Q000494:pharmacology; D004822:Epididymis / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008297:Male; D009249:NADP / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism*; D011467:Prostate / Q000201:enzymology*; D011470:Prostatic Hyperplasia / Q000201:enzymology* / Q000209:etiology; D011506:Proteins / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000378:metabolism
chemical_list: D011506:Proteins; D013196:Dihydrotestosterone; D013739:Testosterone; D009249:NADP; D010088:Oxidoreductases; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase