Sunak, N.; (2007) The effects of ovarian enzyme modulators on folliculogenesis and cyst development in the porcine ovary. Doctoral thesis , University of London.

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Abstract

The first aim of the research conducted as part of this thesis was to investigate the expression and activities of 110HSD enzymes in porcine mural granulosa cells and COCs from small, medium and large antral follicles, as well as from ovarian cysts. Both cloned lipHSD enzymes (lipHSDl and 110HSD2) were expressed in porcine granulosa cells however the results of the expression studies in COCs were inconclusive. In granulosa cells from antral follicles, the 11-dehydrogenase (11P-DH) activities of the lipHSD enzymes increased by approximately 3-fold with antral follicle growth (P<0.01). Similarly, COCs isolated from large follicles had approximately 10-fold higher lip-DH activities than COCs from small follicles (PO.001). These results suggested that antral follicle growth occurred alongside increasing levels of intracellular Cortisol metabolism in both granulosa cells and COCs. In granulosa cells from ovarian cysts, there were significantly decreased net lip-DH activities compared to cells from large antral follicles (P<0.01), suggesting that decreased Cortisol metabolism occurred in the cells of porcine ovarian cysts. The next aim of this thesis was to investigate the levels of ovarian enzyme modulators in FF from small, medium and large antral follicles and in the fluid from ovarian cysts. The levels of inhibitors appeared to decrease in FF with follicle growth but were significantly increased in ovarian cysts (PO.01). These intrafollicular 1 lpHSDl inhibitors in FF and cyst fluid were also able to modulate lipHSD activities in the granulosa cells and COCs. Furthermore, cyst fluid, and the hydrophobic components thereof (which were likely to have included the ovarian enzyme modulators), were shown to significantly increase the rates of porcine oocyte maturation (PO.001). In summary, the findings of the studies conducted in this thesis suggest that the intrafollicular modulators of lipHSDl could influence local cortisol-cortisone inter-conversion in granulosa cells and oocytes during antral follicle growth. In addition the ovarian enzyme inhibitors could possibly influence oocyte maturation with follicle growth. In ovarian cysts however, the high levels of intra-follicular lipHSDl inhibitors in the cyst fluid, and the decreased levels of intracellular Cortisol metabolism observed in the granulosa cells, could be factors contributing to cyst development.

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