Effect of U0126 on AREG-induced connexin-43 phosphorylation, oocyte maturation, and cGMP levels.

<p><b>A,</b> WT preovulatory follicles were preincubated for 30 min with or without U0126 (20 µM), and then stimulated with AREG (100 nM) for 4 h. Oocytes were then released from the follicles and denuded of cumulus cells. The percentage of oocytes that underwent GVBD was scored. Data are the mean ± SEM of eight separate samples for each treatment group. <b>B and C,</b> Preovulatory follicles were preincubated for 30 min in the presence or absence of U0126 (20 µM), and then stimulated with AREG (100 nM) for 2 h. Protein extracts were prepared and used in Western blot analyses to detect the phosphorylation of Cx43 on S262 and S255. The ratio of phosphorylated S262 or S255 to total Cx43 was normalized to control. Data are the mean ± SEM of three separate experiments. Representative blots are shown. <b>D,</b> Cyclic GMP levels were measured in preovulatory follicles cultured with or without U0126 (20 µM) or AG1478 (0.5 µM) for 30 min followed by 2 h stimulation with AREG (100 nM). Data shown are the mean ± SEM of three separate experiments.