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7alpha-hydroxytestosterone affects 1 beta-hydroxysteroid dehydrogenase 1 direction in rat Leydig cells
Guo-Xin Hu1, Qing-Quan Lian, Bing-Bing Chen
1Population Council, 1230 York Avenue, New York, New York 10065, USA.
Endocrinology
|December 18, 2009
Summary
Cytochrome P450 2A1 (CYP2A1) in rat Leydig cells metabolizes testosterone to 7 alpha-hydroxytestosterone (7HT). This 7HT product regulates the 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) enzyme activity direction.
Area of Science:
- Steroid metabolism
- Enzymology
- Reproductive biology
Background:
- Cytochrome P450 2A1 (CYP2A1) metabolizes testosterone.
- CYP2A1 presence in rat testis is known, but its development and function are unclear.
- 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1) interconverts corticosterone and 11-dehydrocorticosterone.
Purpose of the Study:
- Quantify Cyp2a1 mRNA in developing rat testis and Leydig cells.
- Investigate the effect of 7 alpha-hydroxytestosterone (7HT) on 11 beta-HSD1 activity.
Main Methods:
- Real-time PCR to detect Cyp2a1 mRNA.
- Measurement of CYP2A1 activity in Leydig cells.
- Enzyme assays on rat testis microsomes and intact Leydig cells.
Main Results:
- Cyp2a1 mRNA was exclusively found in Leydig cells.
- Adult Leydig cells showed 5-fold higher CYP2A1 activity than immature cells.
- 7HT modulated 11 beta-HSD1 activity, shifting it towards reductase at higher concentrations.
Conclusions:
- CYP2A1 is localized to rat Leydig cells and its activity increases with maturity.
- Testosterone metabolite 7HT regulates 11 beta-HSD1 activity direction in Leydig cells.
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