The antioxidant icariin protects porcine oocytes from age-related damage in vitro

Abstract

Objective: If fertilization does not occur within a specific period, the quality of unfertilized oocytes in the oviduct (<i>in vivo</i> aging) or in culture (<i>in vitro</i> aging) will deteriorate over time. Icariin (ICA), found in all species of <i>Epimedium</i> herbs, has strong antioxidant activity, and is thought to exert anti-aging effects <i>in vitro</i>. We asked whether ICA protects oocytes against age-related changes <i>in vitro</i>.Methods: We analyzed the reactive oxygen species (ROS) levels and expression of antioxidant, maternal, and estrogen receptor genes, and along with spindle morphology, and the developmental competence and quality of embryos in the presence and absence of ICA.Results: Treatment with 5 μM ICA (ICA-5) led to a significant reduction in ROS activity, but increased mRNA expression of glutathione and antioxidant genes (superoxide dismutase 1 [<i>SOD1</i>], <i>SOD2</i>, peroxiredoxin 5, and nuclear factor erythroid 2‐like 2), during aging <i>in vitro</i>. In addition, ICA-5 prevented defects in spindle formation and chromosomal alignment, and increased mRNA expression of cytoplasmic maturation factor genes (bone morphogenetic protein 15, cyclin B1, MOS proto‐oncogene, serine/threonine kinase, and growth differentiation factor‐9). It also prevented apoptosis, increased mRNA expression of antiapoptotic genes (BCL2-like 1 and baculoviral IAP repeat-containing 5), and reduced mRNA expression of pro-apoptotic genes (BCL2 antagonist/killer 1 and activation of caspase-3). Although the maturation and cleavage rates were similar in all groups, the total cell number per blastocyst and the percentage of apoptotic cells at the blastocyst stage were higher and lower, respectively, in the control and ICA-5 groups than in the aging group.Conclusion: ICA protects oocytes against damage during aging <i>in vitro</i>; therefore, it can be used to improve assisted reproductive technologies.