title: Effects of melatonin during IVM in defined medium on oocyte meiosis, oxidative stress, and subsequent embryo development.
abstract: Melatonin may have beneficial effects when used in oocyte maturation and embryo development culture. The effect of melatonin during IVM on meiosis resumption and progression in bovine oocytes and on expression of antioxidant enzymes, nuclear fragmentation and free radicals, as well as on embryo development were assessed. Cumulus-oocyte complexes were matured in vitro with melatonin (10(-9) and 10(-6) M), FSH (positive control), or without hormones (negative control) in defined medium. Maturation rates were evaluated at 6, 12, 18, and 24 hours. Transcripts for antioxidant enzymes (CuZnSOD, MnSOD, and glutathione peroxidase 4 (GPX4)) in oocytes and cumulus cells, nuclear fragmentation in cumulus cells (TUNEL) and reactive oxygen species levels in oocytes (carboxy-H2 difluorofluorescein diacetate) were determined at 24 hours IVM. Effect of treatments on embryo development was determined after in vitro fertilization and culture. At 12 hours, meiosis resumption rates in FSH and melatonin-treated groups were similar (69.6%-81.8%, P > 0.05). At 24 hours, most oocytes were in metaphase II, with FSH showing highest rates (90.0%, P < 0.05) compared with the other groups (51.6%-69.1%, P > 0.05). In cumulus cells, MnSOD expression was higher in FSH group (P < 0.05) whereas Cu,ZnSOD transcripts were more abundant in melatonin group (10(-6)M; P < 0.05). Nuclear fragmentation in cumulus cells was highest in controls (37.4%/10,000 cells; P < 0.05) and lower in FSH and 10(-6)M melatonin (29.4% and 25.6%/10,000 cells, respectively). Reactive oxygen species levels were lower in oocytes matured with 10(-6)M melatonin than in control and FSH groups (P < 0.05). Embryo development from oocytes matured only with melatonin was similar to those matured in complete medium (P > 0.05). In conclusion, although melatonin during IVM in a defined medium does not stimulate nuclear maturation progression it does stimulate meiosis resumption and such treated oocytes support subsequent embryo development. Melatonin also shows cytoprotective effects on cumulus-oocyte complexes.
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil.
authors.forename: Maria Carolina
authors.initials: MC
authors.lastname: Rodrigues-Cunha
authors.affiliation: Departamento de Nutrição e Produção Animal, Faculdade de Medicina Veterinária e Zootecnia-USP, Pirassununga-SP, Brazil.
authors.forename: Lígia G
authors.initials: LG
authors.lastname: Mesquita
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil.
authors.forename: Fabiana
authors.initials: F
authors.lastname: Bressan
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil.
authors.forename: Maite Del
authors.initials: MD
authors.lastname: Collado
authors.affiliation: Departamento de Nutrição e Produção Animal, Faculdade de Medicina Veterinária e Zootecnia-USP, Pirassununga-SP, Brazil.
authors.forename: Júlio C C
authors.initials: JC
authors.lastname: Balieiro
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil.
authors.forename: Kátia R L
authors.initials: KR
authors.lastname: Schwarz
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil.
authors.forename: Fernanda C
authors.initials: FC
authors.lastname: de Castro
authors.affiliation: WTA Watanabe Tecnologia Aplicada, Cravinhos-SP, Brazil.
authors.forename: Osnir Y
authors.initials: OY
authors.lastname: Watanabe
authors.affiliation: WTA Watanabe Tecnologia Aplicada, Cravinhos-SP, Brazil.
authors.forename: Yeda F
authors.initials: YF
authors.lastname: Watanabe
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil.
authors.forename: Lia
authors.initials: L
authors.lastname: de Alencar Coelho
authors.affiliation: Departamento de Medicina Veterinária, Faculdade de Zootecnia e Engenharia de Alimentos-USP, Pirassununga-SP, Brazil. Electronic address: clvleal@usp.br.
authors.forename: Cláudia L V
authors.initials: CL
authors.lastname: Leal
mesh_terms: D000818:Animals; D002417:Cattle / Q000196:embryology*; D004305:Dose-Response Relationship, Drug; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary*; D008540:Meiosis / Q000187:drug effects* / Q000502:physiology; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D009865:Oocytes / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects*
chemical_list: D008550:Melatonin
keywords: Bovine; Gene expression; In vitro fertilization; Nuclear fragmentation; Superoxide dismutase