Objective:Conversion of androstenedione to testosterone, the most potent androgen secreted by the ovary, is carried out by androgenic 17β-hydroxysteroid dehydrogenase (17β-HSD) activity. The molecular basis for this is unclear. We tested the hypothesis that type 5 17β-HSD (17β-HSD5) is responsible for testosterone formation from androstenedione in the human ovary.
Methods:We used primers specific for each type of 17β-HSD to identify quantitatively and directly sequence the polymerase chain reaction products of a human ovary library.
Results:17β-HSD1, 17β-HSD4, and 17β-HSD5 were detected in the library lysate, but not 17β-HSD2 or 17β-HSD3. 17β-HSD5 was the predominant androgenic form of 17β-HSD expressed in human ovary.
Conclusion:These data suggest that 17β-HSD5 may play a major role in testosterone biosynthesis by the human ovary. Further investigation of the regulation of 17β-HSD5 gene expression is warranted with regard to ovarian testosterone secretion in normal and abnormal states of ovarian function, such as polycystic ovary syndrome.
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