Figure 5

Effect of specific inhibition of protein phosphatase 1/2A by okadaic acid on oocyte maturation. A. COC were cultured in the presence of a protein phosphatase 1/2A inhibitor, okadaic acid (2 μM), for 6 or 12 hours of IVM and nuclear status was assessed as described in the Materials and Methods section. Results from COC cultured under control conditions (--■--) or treated with okadaic acid (---■---) are presented as the mean percentages of GV stage oocytes ± SEM of at least three replicates. A total of 217 oocytes were used. Statistical analysis by ANOVA showed that the treatments had significant effects (P < 0.0001). Asterisks indicate significant differences (P < 0.001) from the COC control according to the Bonferroni post hoc test. B. COC were cultured in the presence of okadaic acid (2 μM) and the specific PDE3 inhibitor cilostamide (20 μM) for 24 hours of IVM and were analysed to assess nuclear status. Results are given as the mean percentages of oocytes in GV arrest (open bars), intermediate stage (grey bars) and mature stage (closed bars) ± SEM of at least three replicates. The number of oocytes per treatment is indicated under each bar. Statistical analysis by ANOVA showed that the treatments had significant effects (P < 0.001). Asterisks indicate significant differences (P < 0.001) from control according to the Bonferroni post hoc test.