Addition of beta-mercaptoethanol or Trolox at the morula/blastocyst stage improves the quality of bovine blastocysts and prevents induction of apoptosis and degeneration by prooxidant agents.
This study was conducted to evaluate the effect of beta-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 microM Trolox as well as beta-mercaptoethanol at 100 microM 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 beta-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 beta-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, beta-mercaptoethanol and Trolox added separately from the morula stage protected embryos against oxidative stress and improved the quality of the resulting blastocysts.
Feugang
Jean-Magloire
JM
Université catholique de Louvain, Institut des Sciences de la Vie, Unité des Sciences vétérinaires, Place Croix du Sud 3, B-1348, Louvain-la-Neuve, Belgium.
de Roover
Rudolf
R
Moens
André
A
Léonard
Serge
S
Dessy
Franz
F
Donnay
Isabelle
I
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage*; D017209:Apoptosis / Q000187:drug effects*; D001755:Blastocyst / Q000737:chemistry / Q000187:drug effects / Q000502:physiology*; D002417:Cattle / Q000196:embryology*; D002839:Chromans / Q000008:administration & dosage*; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage; D005260:Female; D005978:Glutathione / Q000032:analysis / Q000096:biosynthesis; D020287:In Situ Nick-End Labeling; D008623:Mercaptoethanol / Q000008:administration & dosage*; D009028:Morula / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D013997:Time Factors
D000975:Antioxidants; D002839:Chromans; D016877:Oxidants; D000431:Ethanol; D008623:Mercaptoethanol; D005978:Glutathione; C010643:6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid