title: The importance of having zinc during in vitro maturation of cattle cumulus-oocyte complex: role of cumulus cells.
abstract: The aim of this study was to investigate the influence of zinc (Zn) on the health of cumulus-oocyte complex (COC) during in vitro maturation (IVM). Experiments were designed to evaluate the effect of Zn added to IVM medium on: DNA integrity, apoptosis, cumulus expansion and superoxide dismutase (SOD) activity of cumulus cells (CC). Also, role of CC on Zn transport during IVM was evaluated on oocyte developmental capacity. DNA damage and early apoptosis were higher in CC matured with 0 μg/ml Zn compared with 0.7, 1.1 and 1.5 μg/ml Zn (p < 0.05). Cumulus expansion did not show differences in COC matured with or without Zn supplementation (p > 0.05). Superoxide dismutase activity was higher in COC matured with 1.5 μg/ml Zn than with 0 μg/ml Zn (p < 0.05). Cleavage and blastocyst rates were recorded after IVM in three maturation systems: intact COCs, denuded oocytes with cumulus cells monolayer (DO + CC) and denuded oocytes (DO). Cleavage rates were similar when COC, DO + CC or DO were matured with 1.5 μg/ml Zn compared with control group (p > 0.05). Blastocyst rates were significantly higher in COC than in DO + CC and DO with the addition of 1.5 μg/ml Zn during IVM (p < 0.01). Blastocyst quality was enhanced in COC and DO + CC compared with DO when Zn was added to IVM medium (p < 0.001). The results of this study indicate that Zn supplementation to IVM medium (i) decreased DNA damage and apoptosis in CC; (ii) increased SOD activity in CC; (iii) did not modify cumulus expansion and cleavage rates after in vitro fertilization; (iv) improved subsequent embryo development up to blastocyst stage; and (v) enhanced blastocyst quality when CC were present either in intact COC or in coculture during IVM.
authors.affiliation: Instituto de Genética Veterinaria Prof. Fernando N. Dulout (IGEVET), Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, CONICET, La Plata, Buenos Aires, Argentina; Cátedra de Fisiología, Laboratorio de Nutrición Mineral, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina.
authors.forename: J M
authors.initials: JM
authors.lastname: Anchordoquy
authors.forename: J P
authors.initials: JP
authors.lastname: Anchordoquy
authors.forename: M A
authors.initials: MA
authors.lastname: Sirini
authors.forename: S J
authors.initials: SJ
authors.lastname: Picco
authors.forename: P
authors.initials: P
authors.lastname: Peral-García
authors.forename: C C
authors.initials: CC
authors.lastname: Furnus
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D018929:Cell Culture Techniques / Q000379:methods / Q000662:veterinary; D018920:Coculture Techniques / Q000662:veterinary; D003470:Culture Media; D054885:Cumulus Cells / Q000502:physiology*; D004249:DNA Damage; D059471:In Vitro Oocyte Maturation Techniques / Q000662:veterinary*; D009865:Oocytes / Q000502:physiology*; D013482:Superoxide Dismutase / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D013482:Superoxide Dismutase; D015032:Zinc