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

• Published in: Theriogenology Vol. 61; no. 1; pp. 71 - 90
• Main Authors: Feugang, Jean-Magloire, De Roover, Rudolf, Moens, André, Léonard, Serge, Dessy, Franz, Donnay, Isabelle
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 2004
• Subjects: Animals; Antioxidants; Antioxidants - administration & dosage; Apoptosis; Apoptosis - drug effects; Blastocyst - chemistry; Blastocyst - drug effects; Blastocyst - physiology; Cattle; Cattle - embryology; Chromans - administration & dosage; Culture Techniques; Dose-Response Relationship, Drug; Embryo culture; Ethanol - administration & dosage; Female; Glutathione - analysis; Glutathione - biosynthesis; In Situ Nick-End Labeling; Mercaptoethanol - administration & dosage; Morula - chemistry; Morula - drug effects; Morula - physiology; Oxidants - pharmacology; Oxidation-Reduction; Oxidative Stress; Time Factors; Antioxidants; Oxidative stress; Cattle; Embryo culture; Apoptosis
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/S0093-691X(03)00191-2

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.