FIGURE 5.

sGC, cGMP, and ERK1/2 mediate proliferative effect of NPY. A–E, cells were cultured under control conditions (NBA/B27/Glu) and 1 μm NPY, 20 μm 8-Br-cGMP (8-Br; cGMP analog), and/or 50 μm ODQ (sGC inhibitor) (A); 500 μm l-arginine (l-ARG) and/or 50 μm ODQ (B); 1 μm NPY or 20 μm 8-Br-cGMP in the presence of 1 μm KT5823 (KT; PKG inhibitor) (C); 1 μm NPY, 20 μm 8-Br-cGMP, and/or 1 μm U0126 (inhibitor of ERK1/2 activation by inhibiting MEK) (D); or 500 μm l-arginine and/or 1 μm ODQ (E) for 3 DIV. BrdU was added for the final 6 h. A, NPY or 8-Br-cGMP both induced a statistically significant increase in the mitotic index. There were no cumulative effects from combined NPY and 8-Br-cGMP treatment. ODQ reduced the effect of NPY down below control levels and had negative effects on basal proliferation rates on its own. B, l-arginine induced a statistically significant proliferative effect, which was also reduced to below control levels by the presence of ODQ. C, NPY or 8-Br-cGMP induced a statistically significant increase in the mitotic index, which was significantly reduced by inhibiting PKG with KT5823. Both treatment with KT5823 on its own and in combination with 8-Br-cGMP resulted in a decrease to below control levels. D, NPY and 8-Br-cGMP both induced a statistically significant increase in the mitotic index, which was reduced back down to control levels by U0126. E, l-arginine statistically significantly increased the mitotic index, which was reduced back down to control levels by the presence of U0126. Data represent mean ± S.E. based on a sample that represents at least 12 wells/condition from at least three independent experiments. One-way ANOVA with Dunnett's multiple comparison test as compared with control condition was performed. *, p < 0.05.