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Addition of β-mercaptoethanol or Trolox® at the morula/blastocyst stage improves the quality of bovine blastocysts and prevents induction of apoptosis and degeneration by prooxidant agents

2003; Elsevier BV; Volume: 61; Issue: 1 Linguagem: Inglês

10.1016/s0093-691x(03)00191-2

1879-3231

Jean M. Feugang, R. De Roover, André Moens, S. Leonard, F. Dessy, Isabelle Donnay,

Ovarian function and disorders

This study was conducted to evaluate the effect of β-mercaptoethanol (a stimulator of glutathione synthesis) and Trolox® (an hydrosoluble analogue of Vitamin E) on bovine embryos cultured from the morula stage (Day 5 post-insemination; pi) under oxidative stress conditions. Culture of embryos with increased doses of Trolox® showed a dose-dependent embryotoxicity on Day 8 pi. The use of 400 μM Trolox® as well as β-mercaptoethanol at 100 μM prevented at least partly (P<0.05) the prooxidant-induced blastocyst degeneration on Day 8. Hatching rates of surviving blastocysts were significantly increased by both antioxidants and β-mercaptoethanol alone improved their mean cell numbers, which was significant in the ICM (P<0.05). Analysis of their effect on Day 7 pi showed that both the antioxidants significantly reduced the prooxidant-induced apoptosis and β-mercaptoethanol diminished the physiological level of apoptosis as well as it stimulated the glutathione synthesis (P<0.05). In addition, a comparison between in vitro- and in vivo-produced embryos showed that the levels of apoptosis were similar at the same age post-insemination (morulae and blastocysts) but increased steadily with the embryonic age in in vitro ones. In conclusion, β-mercaptoethanol and Trolox® added separately from the morula stage protected embryos against oxidative stress and improved the quality of the resulting blastocysts.