Effect of short-term exposure of cumulus-oocyte complex to 3-morpholinosydnonimine on in vitro embryo development and gene expression in cattle

Induction of oxidative stress does not increase the cryotolerance of vitrified embryos

Short-term treatment of mammalian oocytes with different stressors induces stress tolerance of embryos derived from these oocytes. The aims of this study were to evaluate effects on embryo development when there was treatment of oocyte complexes (COCs) used to derive the embryos with hydrogen peroxide (H₂O₂).The COCs were not incubated with H₂O₂: control (0 μM), or were incubated with 25, 50, 75, or 100 μM concentrations of H₂O₂ for 1 h prior to in vitro fertilization, and presumptive zygotes were cultured until day 7. Blastocysts at day 7 of development derived from H₂O₂-treated (25 μM treatment concentration) COCs were vitrified. Percentage of embryos undergoing cleavage was not affected by any treatment, while percentage of embryos developing to the blastocyst stage was less when there was treatment of COCs with 100 μM of H₂O₂. Embryo quality was less when COCs used to derive blastocysts were treated with 50, 75, or 100 μM concentrations of H₂O₂. There were lesser relative abundances of some mRNA transcripts of interest in blastocysts when there was treatment of COCs with H₂O₂. After vitrification, there were no differences in embryo re-expansion and hatching rates compared with fresh and vitrified blastocysts of the control group and those derived from COCs treated with 25 μM H₂O₂. In conclusion, treatment of COCs used to derive blastocysts with H₂O₂ does not induce stress tolerance in vitrified embryos of cattle; however, the viability of these blastocysts is similar to those of the control group.

Melatonin Scavenger Properties against Oxidative and Nitrosative Stress: Impact on Gamete Handling and In Vitro Embryo Production in Humans and Other Mammals

Oxidative and nitrosative stress are common problems when handling gametes in vitro. In vitro development in mammalian embryos is highly affected by culture conditions, especially by reactive oxygen species (ROS) and reactive nitrogen species (RNS), because their absence or overproduction causes embryo arrest and changes in gene expression. Melatonin in gamete co-incubation during in vitro fertilization (IVF) has deleterious or positive effects, depending on the concentration used in the culture medium, demonstrating the delicate balance between antioxidant and pro-oxidant activity. Further research is needed to better understand the possible impact of melatonin on the different IVP steps in humans and other mammals, especially in seasonal breeds where this neuro-hormone system highly regulates its reproduction physiology.

Bovine in vitro embryo production: the effects of fibroblast growth factor 10 (FGF10)

PURPOSE

In an attempt to improve in vitro embryo production, we investigated the effect of fibroblast growth factor 10 (FGF10) during in vitro maturation on the developmental capacity of bovine oocytes.

MATERIAL AND METHODS

Cumulus-oocyte complexes (COCs) were aspirated from follicles of 3-8 mm diameter. After selection, the COCs were matured in medium with or without 0.5 ng/mL of FGF10. The effect of FGF10 during in vitro maturation (IVM) on nuclear maturation kinetics and expansion of the cumulus cells was investigated. Oocyte competence was assessed by the production and development speed of embryos and the relative expression of genes associated with embryo quality.

RESULTS

FGF10 delayed the resumption of meiosis from 8 h onwards, but did not affect the percentage of oocytes reaching metaphase II, nor did it increase cumulus expansion at 22 h of maturation. We found no difference between treatments regarding embryo production, developmental speed, and gene expression.

CONCLUSION

In conclusion, the presence of FGF10 during IVM had no effect on embryo production, developmental speed, and gene expression.