Reactive oxygen species attenuation improves the quality of vitrified-warmed bovine embryos
Feuchard, Viviane Luzia da SilvaOliveira, Clara SladeSaraiva, Naiara ZoccalQuintão, Carolina Capobiango RomanoOliveira, Leticia Zoccolaro
Abstract The aim of this study was to investigate the effects of modulating reactive oxygen species (ROS) in vitrified bovine in vitro produced (IVP) embryos. In experiment I we compared ROS production in fresh and vitrified-warmed blastocysts. In experiment II we evaluated the effects of antioxidant supplementation (100 μM of 2-mercaptoethanol; BME; 0 h to 2 h during warming) on ROS levels in vitrified-warmed blastocysts, and in experiment III we compared the development of fresh and vitrified-warmed blastocysts in the presence (BME) or absence (Control) of antioxidant (100 μM BME; 0 h to 48 h during warming). Higher ROS production (Fresh: 68.48 ± 7.92 vs Vitrified: 123.53 ± 13.15; P<0.05) and lower cell number was observed in vitrified compared to fresh embryos (Fresh: 123.01 ± 5.67 vs Vitrified: 103.04 ± 4.25; P<0.05). Antioxidant supplementation reduced ROS levels (Vitrified: 38.24 ± 1.27 vs. Vitrified/BME: 33.54 ± 1.08; P<0.05) and increased cell number in treated embryos (Vitrified: 100.65 ± 3.98 vs. Vitrified/BME: 112.95 ± 3.72; P<0.05). No differences were observed in the re-expansion rates of vitrified embryos cultured in the absence and presence of BME at 0, 2, and 4 h after warming (P>0.05). The embryo hatching rate did not differ (P>0.05) among embryos from the fresh, vitrified and vitrified/BME groups. However, the total cell numbers were higher (P<0.05) in vitrified embryos supplemented with BME (143.02 ± 6.97) than in vitrified embryos without BME (113.25 ± 5.09) but similar (P>0.05) to that observed in fresh embryos cultured with (150.54 ± 8.99) and without BME (142.71 ± 13.60). It was concluded that the vitrification and warming processes increased ROS levels in blastocysts and its attenuation with BME antioxidant improved embryonic quality.
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