And here is the only info I’ve been able to dig up on enzyme activity in prostrate/penise.
Acta Endocrinol (Copenh) 1975 Jun;79(2):394-402 Related Articles, Links
In vivo uptake and metabolism of 3-h-5alpha-androstane-3alpha,17beta-diol and of 3-h-5alpha-androstane-3beta,17beta-diol by human prostatic hypertrophy.
Horst HJ, Dennis M, Kaufmann J, Voigt KD.
Tritiated 5alpha-androstane-3alpha,17beta-diol (3alpha-diol) and 5alpha-androstane-3beta,17beta-diol (3beta-diol) respectively were administered to patients with benign prostatic hypertrophy (bph) undergoing prostatectomy. In prostate and skeletal muscle homogenates and in plasma the total radioactivity content as well as the formation of metabolites were measured. Histological examination of each ectomized prostate was performed to evaluate the cellular composition of the tissue. After 3alpha-diol injection, a higher uptake of radioactivity in the prostate was obtained than after 3beta-diol. Within 30 min the 3alpha-isomer was very efficiently converted to 5alpha-DHT, while most of the 3beta-isomer remained unchanged. There was, however, also after administration of the 3beta-diol a substantial biconversion to 5alpha-DHT as has been confirmed by recrystallization to constant specific radioactivity. Only after 3beta-diol epiandrosterone was detected in small but significant amounts. 3alpha-diol administration resulted in distinct concentrations of 3beta-diol, whereas the conversion of 3beta-diol to the 3alpha-isomer was insignificant. When comparing the histological composition of the prostatic tissue with the accumulation of radioactivity and the formation of metabolites only a weak correlation between glandular structure and radioactivity uptake after 3alpha-diol administration could be revealed.
PMID: 49141 [PubMed - indexed for MEDLINE]
J Endocrinol 1975 Mar;64(3):529-38 Related Articles, Links
Binding and metabolism of 5alpha-androstane-3alpha, 17 beta-diol and of 5alpha-androstane-3beta, 17 beta-diol in the prostate, seminal vesicles and plasma of male rats: studies in vivo and in vitro.
Krieg M, Horst HJ, Sterba ML.
Binding of 5alpha-androstane-3alpha, 17 beta-diol (3alpha-diol) and 5alpha-androstane-3beta,-17 beta-diol (3beta-diol) in vivo and in vitro to the 100 000 g cytosol fraction of the rat prostate and seminal vesicles as well as to plasma was studied by agargel electrophoresis and sucrose density gradient ultracentrifugation and the results compared with the corresponding findings for 5alpha-dihydrotestosterone (5alpha-DHT). The metabolism of 3alpha-diol and 3beta-diol was also investigated by thin-layer chromatography. The following results were obtained: (1) A specific binding of 3alpha-diol and 3beta-diol by the cytosols could not be demonstrated in vitro, while 5alpha-DHT was specifically bound. (2) In plasma, 3alpha-diol was extensively bound, 3beta-diol less extensively bound, while 5alpha-DHT remained unbound. (3) After intravenous injection of 3alpha-diol, specifically bound radioactivity, increasing within 30 min, was found in the prostate cytosol, while after 3beta-diol injection no binding occurred. (4) Parallel to the increased binding, the total radioactivity in the prostate accumulated within 30 min after 3alpha-diol injection, the uptake being 5-3 times higher than in skeletal muscle. However after 3beta-diol injection, total radioactivity decreased in the prostate within 30 min, the uptake being only 1-5 times higher than in skeletal muscle. (5) One minute after injection of 3alpha-diol, 53% of the extracted radioactivity in the prostate had been converted to 5alpha-DHT, this increased within 30 min to 81%. Thirty minutes after the injection of 3beta-diol, about 32% of the extracted radioactivity in the prostate had been converted to 5alpha-DHT. (6) From the in-vivo and in-vitro experiments it was concluded that 3alpha-diol exerts its biological effects mainly by its conversion into 5alpha-DHT.
PMID: 1133541 [PubMed - indexed for MEDLINE]
Check out those conversion rates! I’m not sure what the carryover is between the seminal vesicles of a rat compared to humans is, but I thought it was interesting.