title: Regulation of sheep oocyte maturation using cAMP modulators.
abstract: Physical removal of mammalian cumulus-oocyte complexes (COCs) from ovarian follicles results in spontaneous resumption of meiosis, largely because of a decrease in cAMP concentrations, causing asynchrony between cytoplasmic and nuclear maturation and decreased oocyte developmental competence. The aim of this study was to modulate cAMP concentrations within ovine COCs to delay spontaneous nuclear maturation and improve developmental competence. Abattoir-derived sheep COCs were cultured for 2 hours (pre-IVM) in 100 μM forskolin (FSK) plus 500 μM 3-isobutyl-1-methylxanthine (IBMX). Pre-IVM (100 μM FSK and 500 μM IBMX) culture increased COC cAMP concentrations 10-fold compared with controls (P < 0.05). With regard to nuclear maturation, with FSK and IBMX and/or with FSH and cilostamide delayed completion of meiosis (metaphase II) by 3 to 4 hours compared with standard IVM (FSH-stimulated induction of meiosis). In this study, pre-IVM (with FSK and IBMX) followed by IVM (with FSH and cilostamide), increased ovine COC cAMP concentrations and delayed, but did not inhibit, completion of nuclear maturation. This did not affect embryo development rates, but increased total cell number of blastocysts compared with IVM with FSH alone (103 ± 6 vs. 66 ± 4 cells, respectively; mean ± SEM; P < 0.05). We inferred that regulation of ovine oocyte cAMP concentrations during IVM improved embryo quality compared with embryos produced by standard IVM methods.
authors.affiliation: The Robinson Institute, Research Centre for Reproductive Health, School of Paediatrics and Reproductive Health, The University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Rose
authors.forename: Robert B
authors.initials: RB
authors.lastname: Gilchrist
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Kelly
authors.forename: Jeremy G
authors.initials: JG
authors.lastname: Thompson
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Sutton-McDowall
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000032:analysis / Q000378:metabolism*; D004622:Embryo, Mammalian / Q000166:cytology / Q000187:drug effects; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods / Q000662:veterinary; D009865:Oocytes / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D009866:Oogenesis / Q000187:drug effects* / Q000502:physiology; D009994:Osmolar Concentration; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011786:Quality Control; D015363:Quinolones / Q000494:pharmacology; D012756:Sheep / Q000196:embryology / Q000378:metabolism / Q000502:physiology
chemical_list: D010726:Phosphodiesterase Inhibitors; D015363:Quinolones; D005576:Colforsin; C021294:cilostamide; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine