P-106: Effect of Cilostamide on Meiotic Arrestof Ovine Oocytes

Background: in vitro maturation (IVM) of oocytes has increasing potential applications in assisted reproductive technology (ART), during which germinal vesicle (GV) oocytes cultured in vitro to produce mature (MII arrested) ones. Although functional, IVM oocytes have low developmental competence compared to in vivo matured oocytes; possibly because IVM comprises asynchrony between nuclear and cytoplasmic maturation in which nuclear maturation precedes cytoplasmic maturation. Therefore, considering the central role of cAMP as the regulator of nuclear maturation, a number of studies have attempted to develop biphasic IVM strategies in which nuclear maturation is transiently delayed through inhibition of several pathways of cAMP production in oocytes. In this study, we investigated the effect of cilostameide, inhibitor of phosphodiesterase 3, on induction of meiotic arrest in ovine oocytes. Materials and Methods: Immature ovine oocytes derived from abattoir ovaries were immediately cultured in presence of three concentration of cilostamide (1,10 and 20 μm) for 22 hours (prematuration culture medium, PMC). Nuclear status of treated oocyte and non-treated oocytes after culture in PMC were assessed using H33342 staning for investigation of meiotic arrest ability of cilostamide. Results: GVBD occurs 4 hours after IVM and at 8 hours post IVM approximately %100 of ovine oocytes undergoes GVBD. In oocytes treated with 1, 10 and 20 μm for 22 hours, respectively 55, 65 and 72 percent of oocytes are arrested at GV stage while only 4% of control oocytes are arrested at GV stage after 22 hours (p< 0.05). 1 μm cilostamide cause lowest meiotic arrest and 20 μm cilostamide cause highest meiotic arrest. futher studies are needed to investigate cytoplasmic maturation markers of prematured oocytes. Conclusion: Cilostamide cause nuclear arrest in ovine oocytes by a dose dependant pathway.