The effect of quercetin in the maturation media on cumulus-granulosa cells and the developmental competence of bovine oocytes.

The present study was designed to investigate the effects of Quercetin on the developmental competence of bovine oocytes and cumulus-granulosa cells (CGs). Two groups of immature cumulus-oocyte complexes (COCs) were subjected to IVM with or without Quercetin. The viability, nuclear status, early and late apoptosis of oocytes and CGs were evaluated using gene expression analysis and staining methods. Embryonic development was assessed morphologically by recording Post-IVF survival, cleavage, and blastocyst rates. The proportion of oocytes reaching the MII stage was greater and the number of early-apoptotic oocytes was lower in the group matured with Quercetin compared to the Control (p < 0.05). Relative upregulation of OCT-4, IGF2R and Bcl-2, and downregulation of CHOP was seen in treated oocytes. Also, downregulation of Bax and upregulation of Glut-4 was detected in treated CGs. The treated oocytes experienced higher post-IVF survival and cleavage rates compared to the untreated group (p < 0.05); more cleaved embryos reached ≥16-cell stage and blastocyst at days 4th and 7th respectively. In addition, total blastocyst rate was significantly improved. It is concluded that supplementing maturation media with Quercetin can enhance the quality of bovine oocytes and endow them with protective potential against early apoptotic damage possibly through CHOP regulation of BCL2 gene family, triggering expression of a gene in CGs to maintain the intactness of oocyte against apoptotic signals and providing oocytes with more energy substrates. It also boosts the subsequent development of oocyte to blastocyst and improves the efficacy of bovine embryo production in vitro.