Preimplantation embryotoxicity after mouse embryo exposition to reactive oxygen species

Elisa Cebral,Isabel Carrasco,David Vantman,Rosita Smith

doi:10.32604/biocell.2007.31.051

Abstract

Exposure of either gametes or embryos to conditions and/or factors that generate oxidative stress has been associated with impaired early embryogenesis. The effects of reactive oxygen species (ROS) on mouse preimplantation development, depending of the ROS-concentration and time of exposition, were studied. Two-cell embryos were incubated with 5, 10, 25 and 50 microM of hydrogen peroxide (H2O2) for 30 and 60 minutes of exposition and allowed to develop for 72 h to study the quality of development. The incubation with 50 microM H2O2 for 30 or 60 minutes, strongly inhibited the 2-cell embryo development as compared to the control (p < 0.001). Twenty-five microM H2O2 produced inhibition of blastocyst formation (p < 0.001) and 10 microM H2O2 significantly decreased the percentages of expanded and hatched blastocysts, which resulted morphologically altered (p < 0.05 and p < 0.01, respectively). The higher H2O2 concentrations were able to elicit necrotic morphology in the 2-cell arrested embryos, while 10 microM H2O2 induced moderate damage with the arrested embryos partially fragmented. In conclusion, important causes for defective preimplantation development and for early embryo losses may be due to oxidative stress because early mouse embryos exposed to ROS for short times arrested at the first cellular cycle (2-cell) and/or impaired embryo differentiation and morphogenesis, being these effects ROS-concentration-dependent.

Highlights

Oxidative stress occurs as the result of an imbalance between the pro-oxidants and the ability of the antioxidants to scavenge the excess reactive oxygen species (ROS) production.It is well known that ROS such as hydrogen peroxide (H2O2), the superoxide anion (O2-) and the hydroxyl radicals (.OH), are generated in several pathological conditions
The present results shows that early preimplantation embryogenesis is severely affected after short time exposition to ROS and that there were thresholds for H2O2 concentration and time of exposition needed to induce embryo arrest or dismorphogenesis
While others authors reported that H2O2 concentrations higher than 60 μM were embryotoxic (Zhang, 2005), we found that the minimal deleterious concentration of hydrogen peroxide (H O) was 10 μM after a exposition for 30 minutes because it was sufficient to block 70% of 2 cells embryos for further development

Summary

Introduction

Oxidative stress occurs as the result of an imbalance between the pro-oxidants and the ability of the antioxidants to scavenge the excess reactive oxygen species (ROS) production.It is well known that ROS such as hydrogen peroxide (H2O2), the superoxide anion (O2-) and the hydroxyl radicals (.OH), are generated in several pathological conditions. High seminal ROS have been related to poor semen quality, loss of sperm function, impaired fertilization and lower pregnancy rates after IVF (Aitken, 1994; Zorn et al, 2003), because lipid peroxidation, even at a level that does not affect motility, may decrease the fertilizing potential spermatozoa (Aitken et al, 1989). These studies suggest that ROS can be produced by living spermatozoa after incubation in aerobic conditions (Iwasaki and Gagnon, 1992)

Methods

Results

Conclusion