FIGURE 1.

Proliferative effect of NPY is mediated via NOS. A–F, cells were grown under control conditions (NBA/B27/Glu) and 1 μm NPY and/or 500 μm l-NAME or d-NAME or 1 μm Y₁ agonist [F7, P34]NPY (Y₁) (A–D) and/or 500 μm l-NAME or d-NAME (E) or 500 μm l-arginine (l-ARG) and 500 μm d-arginine (d-ARG) (F) for 3 DIV. BrdU was added for the final 6 h. NPY induced a statistically significant increase in BrdU⁺ cells (A), nestin⁺ BrdU⁺ precursors (B), the overall mitotic index (C), and the mitotic index of precursor cells (D), which was reduced by l-NAME back down to control levels, but unaffected in general by the inactive enantiomer d-NAME. E, the Y₁ agonist statistically significantly increased the mitotic index, which was reduced back down to control levels by the addition of l-NAME. The inactive enantiomer d-NAME had no effect on Y₁ agonist action. l-NAME and d-NAME had no effects on basal proliferation rates on their own. F, l-arginine statistically significantly increased the mitotic index of cells, whereas the enantiomer d-arginine had no effect. Data represent mean ± S.E. based on a sample that represents at least 12 wells/condition from at least three separate experiments. One-way ANOVA with Dunnett's multiple comparison test as compared with control condition was performed. *, p < 0.05.