Effect of increasing zinc sulphate concentration during in vitro maturation of bovine oocytes

• Published in: Theriogenology Vol. 74; no. 7; pp. 1141 - 1148
• Main Authors: Picco, S.J., Anchordoquy, J.M., de Matos, D.G., Anchordoquy, J.P., Seoane, A., Mattioli, G.A., Errecalde, A.L., Furnus, C.C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.10.2010; [Oxford]: Butterworth-Heinemann; [New York]: Elsevier Science
• Subjects: Animals; Cattle; chemical concentration; Culture Media - chemistry; cumulus oophorus; dietary mineral supplements; DNA Damage; DNA integrity; Dose-Response Relationship, Drug; Embryo, Mammalian - drug effects; embryogenesis; Embryonic Development - drug effects; Fertilization in Vitro - methods; Fertilization in Vitro - veterinary; Glutathione (GSH); Glutathione - metabolism; Glutathione Disulfide - metabolism; in vitro fertilization; In vitro maturation; Oocyte; oocyte metabolism; oocytes; Oocytes - drug effects; Oocytes - physiology; Zinc; zinc sulfate; Zinc Sulfate - pharmacology; oocyte metabolism; DNA integrity; Oocyte; Zinc; In vitro maturation; Glutathione (GSH)
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2010.05.015

The objective was to investigate the effects of supplementary zinc (Zn) during in vitro maturation (IVM) of bovine oocytes. The DNA damage in cumulus cells was low with supplemental Zn concentrations of 1.1 and 1.5 μg/mL in the IVM medium (mean ± SEM index of DNA damage was 67.52 ± 9.32, 68.52 ±13.34, 33.80 ± 4.89, and 34.65 ± 7.92 for supplementation with 0, 0.7, 1.1, and 1.5 μg/mL Zn, respectively; P < 0.01). Total glutathione concentrations did not differ following Zn supplementation of 1.1 and 1.5 μg/mL (3.7 ± 0.4 vs. 4.0 ± 0.5 pmol, respectively, in oocytes; and in cumulus cells, 0.5 ± 0.04 nmol/10 6 cells, combined for both treatments), but were greater (P < 0.01) than supplementation with 0.7 μg/mL (1.8 ± 0.5 pmol in oocytes and 0.2 ± 0.02 nmol/10 6 cumulus cells). Cleavage rate increased (P < 0.05) when Zn was added to the IVM medium at any concentration (67.16 ± 1.17, 73.15 ± 1.15, 74.05 ± 1.23, and 72.76 ± 0.74 for 0, 0.7, 1.1, and 1.5 μg/mL Zn). For these concentrations, subsequent embryo development to the blastocyst stage was 17.83 ± 2.15, 21.95 ± 0.95, 27.65 ± 1.61, and 30.33 ± 2.78%, highest (P < 0.01) in oocytes matured with 1.5 μg/mL Zn. There was an increase (P < 0.05) in mean cell number per blastocyst obtained from oocytes matured with 1.1 and 1.5 μg/mL Zn relative to 0 Zn (IVM alone) and 0.7 μg/mL Zn. In conclusion, Zn during oocytes maturation significantly affected intracellular GSH content and DNA integrity of cumulus cells, and improved preimplantational embryo development. We inferred that optimal embryo development to the blastocyst stage was partially dependent on the presence of adequate Zn concentrations.