title: The effect of glucocorticoids on mouse oocyte in vitro maturation and subsequent fertilization and embryo development.
abstract: Increased glucocorticoid levels, due to medical therapy or stress-related, may affect reproduction via the hypothalamus-pituitary-axis or directly at the oocyte level. We examined the effects of natural (corticosterone) or synthetic (dexamethasone) glucocorticoids on mouse oocyte maturation and underlying changes in extracellular signal-regulated kinase (ERK) phosphorylation patterns. Fertilization and progression up to the blastocyst stage were also evaluated. Oocytes were exposed to corticosterone or dexamethasone (0, 0.25, 2.5, 25 or 250microM) for 17h during in vitro maturation. After maturation, ERK-1/2 activation in oocytes was assessed by SDS-PAGE and immunoblotting, and fertilization and developmental capacity were examined in vitro. Corticosterone exposure during oocyte maturation significantly decreased progression to metaphase II, fertilization and embryo development at the highest concentration. Corticosterone caused a concentration-dependent inhibition of ERK-1/2 activation, with the highest concentration resulting in considerable inhibition of oocyte ERK-1/2 phosphorylation and no blastocyst development. In contrast, dexamethasone had no effect on maturation, fertilization and cleavage, and no effect was seen on ERK-1/2 phosphorylation. Based on these in vitro findings, high glucocorticoid levels may have consequences for subsequent development, although a short exposure to physiologic or stress-related glucocorticoid levels may not represent a hazard to meiosis progression of the oocyte.
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: González
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Ruiz-León
authors.forename: Montserrat
authors.initials: M
authors.lastname: Gomendio
authors.forename: Eduardo R S
authors.initials: ER
authors.lastname: Roldan
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects; D015153:Blotting, Western; D002467:Cell Nucleus / Q000187:drug effects; D002970:Cleavage Stage, Ovum / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D003593:Cytoplasm / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D047108:Embryonic Development / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D007202:Indicators and Reagents; D008297:Male; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects*; D010766:Phosphorylation; D011247:Pregnancy
chemical_list: D005938:Glucocorticoids; D007202:Indicators and Reagents; D003907:Dexamethasone; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D003345:Corticosterone