Short-term exposure to hydrogen peroxide during oocyte maturation improves bovine embryo development

Recent studies have shown that short-term exposure of oocytes to a stressor such as hydrostatic pressure or osmotic stress might induce stress tolerance in embryos. The aim of the present study was to investigate the consequences of short-term hydrogen peroxide (H2O2) exposure to bovine in vitro matured cumulus-oocyte complexes (COCs) on subsequent preimplantation embryo development and apoptosis. in the first experiment, mature COCs were incubated in H2O2 at concentrations ranging between 0.01 and 100 mu mol/l, and subsequently fertilized and cultured. Oocyte incubation with 50-100 mu mol/l of H2O2 resulted in a significantly higher blastocyst yield (47.3%) in comparison with control medium (31.8%), while apoptotic cell ratio was inversely related with H2O2 concentration. In the second experiment, we showed that the stress tolerance after H2O2 exposure was not mediated by increased glutathione content in treated oocytes nor by enhanced fertilization or penetration. Further research should concentrate on the potential role of players that have been associated with stress tolerance in somatic cell lines. Reproduction (2010) 139 505-511