Abstract: This study was designed to investigate the effect of epicatechin (EC) on mitochondrial DNA (mtDNA) copy number and developmental competence of rat oocytes following maturation and culture in vitro. Cumulus-oocyte complexes were respectively cultured in the maturation medium supplemented with different concentrations of EC (0, 5, 10, 15 and 20 μmol/L) for 16 h. And then the mtDNA copy number in matured oocytes was detected with the method of Real-time PCR. Moreover, the subsequent developmental competence of embryos from parthenogenetic activation (PA) was examined. The PCR result showed that the mtDNA copy number in each EC treatment group were increased than that of control group, and there was remarkably increase in the both groups of 10 and 15 μmol/L compared with the control group (P<0.05), but the number of 10 μmol/L group was more closed to that of the nature ovulation cycle oocytes (P>0.05). Furthermore, the result of in vitro culture showed that adding with 10 μmol/L EC into the maturation medium, there were no significant effect in the maturation rate of oocytes (P>0.05), but the developmental rate of blastocyst after PA was significantly improved than that of control group (P<0.05). The datas above showed that adding 10 μmol/L EC into the maturation medium could increase the mtDNA copy number of oocytes, and contribute to improve its subsequent developmental competence.

Key words: epicatechin; oocyte; mtDNA; developmental competence