β-carotene improves oocyte development and maturation under oxidative stress in vitro

Recently, the mean maternal age at first birth has been continuing to increase. The decline in the age-related fertility is due to the reduction in the number and the quality of the oocyte. An elevation in intra-ovarian reactive oxygen species (ROS) is correlated with the increase in maternal age, and the oxidative stress is involved in the decline in oocyte quality. Although beta-carotene, a very effective quencher of ROS, has been found to have the beneficial contribution to the ovarian development and steroidogenesis, it is unknown the effect of beta-carotene on the oocyte development especially oocyte maturation. This investigation aimed to explore the beneficial contribution of beta-carotene on oocyte maturation under oxidative stress and the underlying mechanism. We found that the oxidative stress induced by ROS reagent Rosup inhibited oocyte development/maturation and parthenogenetic activation which could be dramatically rescued by beta-carotene (57.1 +/- 4.7% vs 78.9 +/- 3.8%; p<0.05) in vitro. The underlying mechanisms include that beta-carotene not only reduces ROS formation and cell apoptosis, but also it can restore actin expression, cortical granule-free domain (CGFD) formation, mitochondria homogeneous distribution, and nuclear maturation. The data suggest that beta-carotene acts as a potential antioxidant in the oocyte. Therefore, the findings from this investigation provide the fundamental 7knowledge for using beta-carotene as an antioxidant to improve the oocyte quality and even the ovarian function.