EFFECTS OF ANTIOXIDANT SUPPLEMENTATION TO IN VITRO MATURATION MEDIUM ON OOCYTE DEVELOPMENT OF DOMESTIC CAT (FELIS CATUS).

Mammalian oocytes require a variable period of in vitro maturation (IVM) to develop to metaphase II stage. Oocytes recovered from preovulatory follicles show a reduction in cleavage frequency and blastocyst development of cat embryos produced. It was demonstrated that high oxygen concentration compromises nuclear maturation rates and worsens the oxidative stress during IVM. Incubated oocytes show severely high quantities of superoxide dismutase (SOD), glutathione reductase (GSR), glutathione peroxidase (GPX1) and catalase (CAT) mRNA and this effect results in a protective mechanism against oxidative stress. Examining the follicular fluid oxidants and antioxidants it is possible to understand the composition changes in vivo and optimize the conditions of IVM. To improve the development of cat oocyte, we studied the effects of the addition of SOD and CAT to IVM medium on developmental competence and embryo production. Cat oocytes were collected from fresh excised ovaries and cultured in a maturation medium supplemented without (untreated group) or with (treated group) SOD (25UI/ml) and CAT (50UI/ml) for 24h. Both groups were subjected to fertilization in vitro (IVF) with fresh epididymal sperm extracts for 12h. After IVF, the zygotes were cultured in a synthetic oviduct fluid medium for 8 days. There were no significant difference in the maturation rates (86.4% vs 87.6%) between the groups, nevertheless antioxidant supplementation. The frequency of blastocyst development from oocytes of treated group (36.0%) was higher (p<0.05) than untreated group (28.4%). Our data indicate that the supplementation of SOD and CAT into IVM medium may improve blastocyst development of cat oocytes after IVF. Gupta S, Choi A, Yu HY, Czerniak SM, Holick EA, Paolella LJ, Agarwal A, Combelles CM. Fluctuations in total antioxidant capacity, catalase activity and hydrogen peroxide levels of follicular fluid during bovine folliculogenesis. Reprod Fertil Dev. 2011;23(5):673-80. Luu VV, Hanatate K, Tanihara F, Sato Y, Do LT, Taniguchi M, Otoi T. The effect of relaxin supplementation of in vitro maturation medium on the development of cat oocytes obtained from ovaries stored at 4°C.