P-94: The Effect of Calcium Ionophore A23187 and Ethanol on Parthenogenetic Activation of Mouse Oocytes in Presence of Hydrostatic Pressure and Cy-tochalasin B

Background: Parthenogenetic activation of mammalian oocytes using artificial stimuli is commonly used in various reproductive bio-techniques. Calcium ionophore is known to elevate intracellular calcium levels in the cytoplasm of oocytes through the influx of calcium from extracellular spaces. Ethanol promotes a single intracellular Ca2+ increase of greater and longer amplitude than the initial increase observed at fertilization. Hydrostatic pressure can act as a mechanical stimulator that rearranges egg contents. In this study, we investigated the effect of calcium ionophore and ethanol on parthenogenetic activation of mouse oocytes in presence of hydrostatic pressure. Materials and Methods: 6 to 8-week-old female NMRI mouse were super-ovulated by an injection of 10 IU of PMSG, followed by 10 IU HCG 48 hours later. Metaphase II oocytes were collected from oviduct 14 hr after HCG injection. Oocytes transferred to T6 medium supplemented with different concentration of calcium 0, 1.7, 3.4 mM (treatments, II,), and then treated with temporal sequential combinations of 2 chemical activators [5μM of calcium ionophore (CI) for 5 minutes (group 1), and 7% ethanol (ET) for 5 minutes (group 2)] followed by exposure to 20 mmHg pressure for 20 minutes. Oocytes from two groups were transferred to T6 medium supplemented with different concentration of calcium and 5μg/ml CB for 4 hours. Oocytes were cultured for 72 hours and embryo development was assessed. Results: In 1 and 2 group treatments, II, the percentage of cleavage was 20.42, 82.78, 51.6, 18.51, 69.63, 45.36%, respectively. Cleavage rate in 1 group was higher than 2 group (p<0.05). The highest cleavage rate associated with treatment II which were significantly different with treatments, and 2 group (p<0.05). Conclusion: Exposure of oocytes to HP, followed by exposure to CI could improve embryonic development and by effecting calcium channels leads to increase rate of cleavage in the mouse oocyte, probably.