FIGURE 9.

NPY inhibits IL-1β-induced iNOS protein levels. A, confocal microscopy photomicrographs illustrate microglial cells treated with 1 μm NPY and 1.5 ng/ml IL-1β for 6 h to assess the role of NPY and IL-1β in iNOS synthesis. To determine whether NPY was blocking the synthesis of NO induced by IL-1β treatment, cells were stained for NF-κB (in green), for CD11b (in red), and with Hoechst 33342 (nuclei in blue). An increase of iNOS labeling was induced by IL-1β administration and inhibited to an intensity comparable with fluorescence control values when treated with NPY. Scale bar, 10 μm. B, to provide a quantitative analysis, iNOS protein values were measured by Western blot. NPY inhibited IL-1β-induced iNOS levels. A representative blot is shown below the graph. Data are expressed as mean ± S.E. (n = 4) and as a percentage of control (**, p < 0.01; ***, p < 0.001 using Bonferroni's multiple comparison test).