help button home button Endocrine Society JCEM ENDO 08
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Tunn, S.
Right arrow Articles by Krieg, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Tunn, S.
Right arrow Articles by Krieg, M.
Right arrowPubmed/NCBI databases
*Compound via MeSH
*Substance via MeSH
Medline Plus Health Information
*Seniors' Health

Journal of Clinical Endocrinology & Metabolism, Vol 71, 732-739, Copyright © 1990 by Endocrine Society

ARTICLES

Effect of aging on kinetic parameters of 3 alpha(beta)-hydroxysteroid oxidoreductases in epithelium and stroma of human normal and hyperplastic prostate

S Tunn, R Haumann, J Hey, SH Fluchter and M Krieg
Institute of Clinical Chemistry and Laboratory Medicine, University Clinic Bergmannsheil, Bochum, West Germany.

The accumulation of 5 alpha-dihydrotestosterone (DHT), particularly in stroma, is a possible etiological factor in regard of the age-dependent development of benign prostatic hyperplasia (BPH). In this context, we have recently demonstrated age-dependent alterations of 5 alpha- reductase, which is responsible for the irreversible conversion of testosterone to DHT. Therefore, it was also of interest to study possible age-dependent alterations of those enzymes mainly involved in the reversible metabolism of DHT to 5 alpha-androstanediols. Thus, we determined, in the presence of NADPH/NADP+, kinetic parameters [Km and maximum velocity (Vmax)] of 3-hydroxysteroid oxidoreductases (3 alpha- HSORred, 3 beta-HSORred, and 3 alpha-HSORox) in separated epithelium and stroma of 10 normal (NPR) and 20 hyperplastic prostates (BPH) and correlated the data with the age of the donors (15-86 yr). The mean Km (nanomolar concentrations +/- SEM) of 3 alpha-HSORred was significantly (P less than 0.01) higher in epithelium (NPR, 1391 +/- 181; BPH, 2150 +/- 157) than in stroma (NPR, 778 +/- 22; BPH, 749 +/- 62), indicating the presence of epithelial and stromal enzymes. The mean Km values of 3 beta-HSORred and 3 alpha-HSORox were similar. Concerning 3 alpha- HSORred, the mean potential capacity, i.e. the quotient of Vmax/Km (+/- SEM), was significantly (P less than 0.01) higher in epithelium (0.56 +/- 0.08) than in stroma (0.19 +/- 0.02) of NPR, while in BPH nearly identical mean potential capacities were found in epithelium (0.33 +/- 0.04) and stroma (0.26 +/- 0.02). The respective Vmax/Km of 3 beta- HSORred and 3 alpha-HSORox were significantly (P less than 0.05) lower. In addition, the potential capacity of all three enzymes was distinctly lower than the potential DHT-forming capacity of 5 alpha-reductase. With advancing age, the Vmax/Km decreased significantly (P less than 0.001; 3 alpha-HSORred and 3 beta-HSORred) or tendentiously (3 alpha- HSORox) in epithelium, while in stroma a significant (P less than 0.001; 3 alpha-HSORred and 3 alpha-HSORox) or tendentious (3 beta- HSORred) increase with age was found. Our results indicate that aging has a significant impact on DHT-removing enzymes. However, these enzymes counterbalance only in part the strong potential capacity of 5 alpha-reductase.




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals
Copyright © 1990 by The Endocrine Society