Influences of dehydroepiandrosterone acetate on ovarian oocytes in mature cycling rats

DHEA-mediated inhibition of the pentose phosphate pathway alters oocyte lipid metabolism in mice

Women with polycystic ovary syndrome (PCOS) and hyperandrogenism have altered hormone levels and suffer from ovarian dysfunction leading to subfertility. We have attempted to generate a model of hyperandrogenism by feeding mice chow supplemented with dehydroepiandrosterone (DHEA), an androgen precursor that is often elevated in women with PCOS. Treated mice had polycystic ovaries, low ovulation rates, disrupted estrous cycles, and altered hormone levels. Because DHEA is an inhibitor of glucose-6-phosphate dehydrogenase, the rate-limiting enzyme in the pentose phosphate pathway, we tested the hypothesis that oocytes from DHEA-exposed mice would have metabolic disruptions. Citrate levels, glucose-6-phosphate dehydrogenase activity, and lipid content in denuded oocytes from these mice were significantly lower than controls, suggesting abnormal tricarboxylic acid and pentose phosphate pathway metabolism. The lipid and citrate effects were reversible by supplementation with nicotinic acid, a precursor for reduced nicotinamide adenine dinucleotide phosphate. These findings suggest that elevations in systemic DHEA can have a negative impact on oocyte metabolism and may contribute to poor pregnancy outcomes in women with hyperandrogenism and PCOS.

On fragmentation and elimination of ovarian oocytes

Examination of numerous fragmented oocytes in the ovary revealed an asynchronous relationship between nuclear and cell divisions. The asynchrony was observed in non-fragmented oocytes as well and was considered to be one of the common processes leading towards oocyte elimination of the ovary. The present study additionally demonstrates the morphology of follicle cell degeneration observed on the surface of fragmented oocytes.

On induced fragmentation of ovarian oocytes

Fragmentation of oocytes was induced in the ovary, via ovulation suppression, by administration of dehydroepiandrosterone acetate (DHA-Ac) to mature cycling rats. The maximal fragmentation ratio, 15.0 +/- 3.2%, was obtained by 10 mg/100 g b.wt/day for 7-day administration of DHA-Ac. The relationship of fragmentation to the first stage of meiosis is also discussed.