Efeito da cilostamida e das metades foliculares no bloqueio da retomada da meiose e no nível de AMPc em oócitos bovinos

Abstract

The aims of this study were (1) to evaluate the effects of cilostamide and follicular hemisections on the blockage of in vitro oocyte meiotic resumption in bovine cumulus oocyte complexs (COCs), (2) to investigate the reversibility of cilostamide effect on meiotic resumption, and (3) to quantify the levels of cAMP in COCs, denuded oocytes (DO) and cumulus cells (CC) after culturing COCs in presence of cilostamide and follicular hemisections. To this end, bovine oocytes were subjected to a pre-maturation period of 12 h in medium containing 10 µM cilostamide, follicular hemisections or combination of both and,then, submitted to in vitro maturation. To evaluate the reversibility of cilostamide effect, at the end of this culture period, COCs were washed and placed in maturation medium without cilostamide for 12, 14, 16, 18, 20, 22 and 24 hours. To investigate the levels of cAMPc, COCs subject to pre-maturation for 6 h were used to measure the levels of cAMP. After 12 hours of culture, groups COCs were fixed to assess chromatin configuration and meiotic rogression. The results showed that COCs cultured in presence of cilostamide and follicular hemisections had significantly higher percentages of oocytes at germinal vesicle stage (94%), after a period of 12 h of pre-maturation, than COCs cultured in other treatments. After blocking treatment, 75% of oocytes reached metaphase II after 16 h of maturation, emphasizing that the treatment is not toxic to oocytes. Moreover, oocytes cultured in medium containing cilostamide and follicular hemisctions had significantly higher levels of cAMP when compared to other treatments. It is concluded that cilostamide and follicular hemisections interact and promotes the maintenance of oocytes at germinal vesicle stage by increasing the levels cAMP in cultured COCs.