EFFECT OF CYSTEAMINE ON GLUTATHIONE LEVEL AND DEVELOPMENTAL CAPACITY OF BOVINE OOCYTE MATURED IN-VITRO

The present study was carried out to evaluate if the addition of cyste amine to the culture medium during in vitro maturation of bovine oocyt es increased the glutathione (GSH) levels in the mature oocytes, and i f these changes may promote an improvement on in vitro development to the blastocyst stage. Follicular oocytes from slaughterhouse ovaries w ere matured in TCM 199 supplemented with 10% (v/v) fetal calf serum, h ormones, and O (control), 25, 50, or 100 mu M of cysteamine for 24 hr. After in vitro maturation the oocytes were fertilized and cultured fo r 8 days. The percentage of embryos that developed to the blastocyst s tage was significantly higher (P < 0.01) for oocytes matured in medium containing 100 mu M of cysteamine than for those matured in control m edium. Moreover, the intracellular GSH levels were increased (P < 0.05 ) in oocytes matured with 100 mu M of cysteamine with respect to contr ol. No differences were observed in maturation and cleavage rates, and in the mean cell numbers per blastocyst among treatments (P > 0.05). These results indicate that the addition of thiol compounds such as cy steamine to maturation medium increases the efficiency of in vitro bla stocyst production from immature bovine oocytes. The higher levels of GSH in oocytes matured in the presence of cysteamine suggest that the beneficial effects of cysteamine on in vitro maturation and subsequent development after in vitro fertilization are mediated by GSH. (C) 199 5 Wiley-Liss, Inc.