In vitro effects of dexamethasone on mouse ovarian function and pre-implantation embryo development

The effect of dexamethasone (5-80 microg/ml) on ovarian function and embryo development was studied in mice. The follicle bio-assay revealed no effects of DEX up to 40 microg/ml on folliculogenesis and oogenesis, whereas 80 microg/ml hampered follicle differentiation and oocyte maturation. Androgen, estrogen and progestin secretion patterns were strongly impaired at all doses levels. However, the ovulation-induced progesterone increase indicating that the steroid pathway was activated in presence of DEX. Applying the oil-free mouse embryo assay no alteration of DEX on the first cleavage stages were observed whereas blastocyst rate decreased from 20 microg/ml DEX onwards, and hatching capacity was already impaired in presence of 10 microg/ml DEX. In conclusion, steroidogenesis was affected from 5 microg/ml onwards and the minimum effective inhibitory dose was set at 10 microg/ml for early embryo development. Based on these in vitro findings, physiological or therapeutic levels of glucocorticosteroids are unlikely to affect female fertility.