200 Effect of coenzyme Q10 supplementation on bovine oocyte maturation and embryo development

Coenzyme Q10 (CoQ10) is an essential carrier in the mitochondrial electron transport chain and has been used in vitro to improve mitochondrial function. CoQ10 has improved bovine IVM during heat stress and oocyte and embryo functions in vitro and in vivo under stress (Gendelman and Roth 2012 Biol. Reprod. 87, 118). Our aim was to determine the effects of CoQ10 supplementation at 25 µM, 50 µM, and 100 µM in bovine IVM medium on oocyte maturation and quality, mitochondrial mass, and subsequent development after parthenogenetic activation (PA). Cumulus-oocyte complexes (COCs) collected from abattoir-derived bovine ovaries were matured for 21–23 h in IVM medium supplemented with 25 mM, 50 mM, or 100 mM CoQ10 or without CoQ10 (control). Following maturation, COCs were denuded to assess the maturation rate. In Exp. 1, MII oocytes were stained with GSH and ROS as indicators of oocyte quality (five replicates), and MitoTracker Green was used to determine the mitochondrial mass in the oocytes (four replicates). The fluorescence intensity was analyzed by ImageJ. In Exp. 2, for PA, matured oocytes from each group were activated in 5 µM ionomycin for 5 min, followed by 4 h incubation in 2 mM 6-dimethylaminopurine and 10 µg mL⁻¹ cycloheximide. PA embryos were cultured in SOF in four-well dishes under oil. Cleavage and blastocyst rates were assessed on Days 2 and 8 post-activation, respectively. Blastocyst rate was calculated as the number of blastocysts out of cleaved embryos. Fluorescence intensity data were analyzed by generalized linear model and embryo development data were analyzed by one-way ANOVA. Differences were deemed significant if P < 0.05. Results were presented as mean ± standard deviation. In total, 1293 COCs were collected in this study (334 for control, 318 for 25 mM, 332 for 50 mM, and 309 for 100 mM). After IVM, 326 MII oocytes were used for PA (three replicates), 88 oocytes for GSH staining, 95 oocytes for ROS staining, and 69 oocytes for MitoTracker staining. There were no differences in maturation rates among the groups (control, 62.7 ± 19.5%; 25 mM, 71.4 ± 7.0%; 50 mM, 74.0 ± 6.6%; 100 mM, 69.1 ± 10.2%; P > 0.05). Although no differences were observed in the relative levels of GSH and ROS among the groups, the mitochondrial mass in the 100 mM CoQ10 group was higher than in the control and 25 mM CoQ10 groups (1.92 vs. 1.00 and 0.86, respectively; P < 0.05). No differences were observed in the blastocyst rates of PA embryos among the groups; whereas, the cleavage rate in the 100 µM CoQ10 group was lower than in the control and 50 mM CoQ10 groups (73.2 ± 5.6% vs. 85.3 ± 4.1% and 88.7 ± 3.2%, respectively; P < 0.05). In conclusion, lower concentrations of CoQ10 supplementation do not affect oocyte maturation and quality or embryo development, whereas a higher concentration of CoQ10 (100 mM) increases mitochondrial mass in bovine oocytes and decreases their cleavage rate after PA.