Melatonin promotes embryonic development and reduces reactive oxygen species in vitrified mouse 2-cell embryos

Two-cell embryos of mouse were vitrified by the open-pulled straw (OPS) method. The vitrified embryos were warmed and introduced into M16 medium for culture that contains melatonin at different concentrations (10^-3, 10^-5, 10^-7, 10^-9, 10^-11m). This process caused reactive oxygen species (ROS) formation and jeopardized the development of the embryos. Melatonin, at different concentrations, significantly suppresses ROS production and promotes embryonic development in vitrified embryos compared with untreated ones. The mechanistic studies indicated that the beneficial effects of melatonin on vitrified 2-cell embryos of mouse were melatonin receptor (MT1 and MT2) independent. The direct free radical scavenging activity, the enhancement of endogenous glutathione levels, and the anti-apoptotic capacity of melatonin may account for its protective effects on vitrified embryonic development.