Quercetin influences in vitro maturation, apoptosis and metabolically active mitochondria of goat oocytes

The present study aimed to investigate the effect of quercetin as an alternative antioxidant to cysteamine on in vitro maturation. Oocytes were collected from goat ovaries, destined for in vitro maturation and distributed into three groups: CIS group, oocytes were immersed in MIV base medium; in Groups Q4 and Q8, oocytes were immersed in the medium of the CIS group, adding 4 mu M or 8 mu M of quercetin, respectively, and cultured for 24 h at 38.5 degrees C with 5% CO2. The CIS and Q4 groups presented the same percentage of expanded cumulus cells, but the per cent in the Q8 group was significantly lower than that of the other groups (P<0.05). The oocyte retraction rate in the Q8 group was higher (P<0.05) than in the CIS and Q4 groups. Treatment with 8 mu M of quercetin presented a lower proportion of expanded oocytes than the CIS group and 4 mu M of quercetin (P<0.05). The percentage of MII oocytes was higher in the Q4 group than in the CIS group (P<0.05), but the percentages in the CIS and Q8 groups were similar. The rate of apoptosis was higher in the CIS group than in the other groups (P<0.05). In addition, oocytes matured with 4 mu M quercetin showed higher mitochondrial activity than matured oocytes in the CIS and Q8 groups (P<0.05). In conclusion, 4 mu M of quercetin can be used as an alternative to cysteamine in the in vitro maturation of goat oocytes.