Gas chromatography-mass spectrometry of androgens in equine ovarian follicles at ultrastructurally defined stages of development. Identification of 19-nortestosterone in follicular fluid.

This research explores the identification and measurement of specific androgens in the ovarian follicles of horses using gas chromatography-mass spectrometry. The findings suggest that the high level of certain androgens could lead to an overestimation of testosterone content when measured by Radioimmunoassay (RIA).

Using Gas Chromatography-Mass Spectrometry for the Study

• The study was conducted using follicular fluid obtained from horse follicles at different developmental stages. These stages were first identified through ultrastructural studies which allowed for precise selection of follicles at different developmental points.
• Gas chromatography-mass spectrometry was used in conjunction with stable isotope dilution to examine the contents of the follicular fluid. This method allowed for a highly accurate and sensitive measurement of different androgens in the samples.

Identification and Observations of Androgen Levels

• Using gas chromatography-mass spectrometry, it was found that the follicular fluids contained high levels of 4-estrene-3,7-dione and 17 beta-hydroxy-4-estren-3-one. The latter was often detected at levels approximately 10 times higher than testosterone.
• The presence of these two androgens, particularly at such high levels, suggests the potential existence of an aromatizing pathway in the mare ovary. 19-norsteroids would be intermediates in this pathway.

Implication of the Findings

• The research indicated that the high level of 19-norsteroids could potentially lead to overestimation of testosterone levels when measured through techniques like Radioimmunoassay (RIA). This highlights the importance of validating steroid measurements in follicular fluid using gas chromatography-mass spectrometry in combination with stable isotope dilution.
• These findings provide a deeper understanding of hormonal pathways in the equine ovary and could help shape further research into equine reproduction and endocrinology.