title: Effect of 1,4,6-androstatriene-3,17-dione (ATD), 4-hydroxy-4-androstene-3,17-dione (4-OH-A) and 4-acetoxy-4-androstene-3,17-dione (4-Ac-A) on the 5 alpha-reduction of androgens in the rat prostate.
abstract: The present study reports the effects exerted by 1,4,6-androstatriene-3,17-dione (ATD), 4-hydroxy-4-androstene-3,17-dione (4-OH-A) and 4-acetoxy-4-androstene-3,17-dione (4-Ac-A), three steroids known to inhibit the aromatization of androgens to estrogens, on the in vitro metabolism of labelled testosterone (T), dihydrotestosterone (DHT) and androstenedione (delta-4-A) in the ventral prostate of adult male rats. It has been found that ATD, in the concentration tested, does not influence the conversion of labelled T into DHT, but decreases the formation of 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol (diols). On the contrary, 4-OH-A and 4-Ac-A simultaneously decrease the formation of DHT and the diols. When T is used as the substrate, the presence in the medium of these three steroids enhances the formation of delta-4-A and of 5 alpha-androstanedione (5 alpha-A). ATD, but not 4-OH-A and 4-Ac-A inhibits the conversion of labelled DHT into the diols. The transformation of labelled delta-4-A into 5 alpha-A is not modified by either ATD or 4-OH-A, while 4-Ac-A exerts only a small inhibition. These results suggest that the three aromatase inhibitors tested are able to profoundly modify the metabolism of T in the ventral prostate of the rat. In particular: 4-OH-A and 4-Ac-A are able to inhibit the conversion of T into DHT; ATD is able to inhibit the conversion of DHT into the diols; ATD and 4-OH-A do not inhibit the process of 5 alpha-reduction of delta-4-A into 5 alpha-A, while 4-Ac-A exerts only a minor effect. It is suggested that in the ventral prostate of the rat there are two different 5 alpha-reductase isoenzymes, one sensitive to the inhibitory effect of the steroid tested and which is responsible for the conversion of T into the 5 alpha-reduced metabolites of the 17-OH series (DHT and the diols), and a second one, insensitive to the effects of the three steroids, which affects the conversion of delta-4-A into 5 alpha-A.
mesh_terms: D000728:Androgens / Q000378:metabolism*; D000733:Androstatrienes / Q000494:pharmacology*; D000735:Androstenedione / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D013196:Dihydrotestosterone / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D011467:Prostate / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000378:metabolism
chemical_list: D000728:Androgens; D000733:Androstatrienes; D013196:Dihydrotestosterone; C011658:androsta-1,4,6-triene-3,17-dione; D013739:Testosterone; D000735:Androstenedione; C022569:4-acetoxy-4-androstene-3,17-dione; C014594:formestane