Expression of 17 beta-hydroxysteroid dehydrogenase type 5 in human ovary: a pilot study.

OBJECTIVE

Conversion of androstenedione to testosterone, the most potent androgen secreted by the ovary, is carried out by androgenic 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity. The molecular basis for this is unclear. We tested the hypothesis that type 5 17 beta-HSD (17 beta-HSD5) is responsible for testosterone formation from androstenedione in the human ovary.

METHODS

We used primers specific for each type of 17 beta-HSD to identify quantitatively and directly sequence the polymerase chain reaction products of a human ovary library.

RESULTS

17 beta-HSD1, 17 beta-HSD4, and 17 beta-HSD5 were detected in the library lysate, but not 17 beta-HSD2 or 17 beta-HSD3. 17 beta-HSD5 was the predominant androgenic form of 17 beta-HSD expressed in human ovary.

CONCLUSION

These data suggest that 17 beta-HSD5 may play a major role in testosterone biosynthesis by the human ovary. Further investigation of the regulation of 17 beta-HSD5 gene expression is warranted with regard to ovarian testosterone secretion in normal and abnormal states of ovarian function, such as polycystic ovary syndrome.