Effects of SNAP and/or cilostamide supplementation during bovine oocyte in vitro maturation on maturation kinects and embryo production

Nitric oxide (NO) is a gaseous free radical involved in many physiological processes in mammals, which has been detected in ovaries, oocytes and embryos. NO activates soluble guanylate cyclase (sGC), and results in the production of cyclic guanosine monophosphate (cGMP). This nucleotide is involved in oocyte maturation and consequently in the success of fertilization. In addition to cGMP, another cyclic nucleotide, cyclic adenosine monophosphate (cAMP), is also related to maturation. The levels of these nucleotides are balanced by synthesis and degradation, made by phosphodiesterases (PDEs). The aim of this study was to analyze the effect of NO donor (SNAP) and PDE3 inhibitor (cilostamide) during IVM on maturation kinects in bovine oocytes and in vitro embryo production. Experiment I, cumulus-oocyte complexes (COCs) were cultured in maturation medium with a NO donor (0.1 µM S-nitroso-N-acetylpenicillamine - SNAP) associated or not with a PDE3 inhibitor (20 µM cilostamide) at 28h and after this period, the maturation kinects was evaluted. In Experiment II, COCs were cultured for 28 h in maturation medium with NO donor (0.1 µM SNAP) or PDE3 inhibitor (20 µM cilostamide), or both, after this period the COCs were submited to IVF and IVC, the developmental rates was evaluated. Statistical analyses were performed using the SAS System. Data were tested for normal distribution and transformed to arcsine. The percentages of maturation rates and embryo production were analyzed by one-way ANOVA followed by Bonferroni post hoc test). In experiment I, SNAP+cilostamide had lower MII rates at 24 h IVM (50.0 ± 2.0%, P 0.05), but at 28 h of IVM all groups were similar (66.6 to 71.4%, P u003e 0.05). In experiment II, cleavage rates were lower in the SNAP+cilostamide association (55.1 ± 7.6%, P 0.05). Blastocyst rates on D7 were similar for control, SNAP and cilostamide (38.7 ± 5.8, 37.9 ± 6.2 and 40.5 ± 5.8 %, respectively, P u003e 0.05), but lower for SNAP+cilostamide (25.7 ± 6.9%, P u003c 0.05). Similar trend was observed for D8 blastocyst and hatching rates, where SNAP+cilostamide had lowest rates for both parameters (P u003c0.05). In conclusion, delaying meiosis by combining SNAP and cilostamide decreased embryos production.