Figure 2.

5-HT_3A-driven GFP is expressed in geniculate ganglion neurons that innervate the tongue. A, Confocal Z-projection of 10 0.7 μm optical slices of geniculate ganglion from a 5-HT_3AGFP mouse showing expression of GFP (green) and P2X₃ (magenta). Scale bar, 100 μm. B, Histograms of GFP and P2X₃ normalized immunoreactivity of individual cells showing that whereas the P2X₃ staining shows a unimodal normal distribution (mean 0.58), the GFP population is bimodal suggestive of high-expressing (mean = 0.69) and low- or nonexpressing populations (mean 0.12). Insert at upper right shows the higher expressing population rescaled along the abscissa. C, Scatterplot comparing relative fluorescence intensity for normalized P2X₃ and GFP immunoreactivity. No correlation exists between the two factors (r = 0.16, Pearson's correlation; n = 5 mice, 9 ganglia, 682 cells). Dotted lines (B, C) indicated threshold for each channel. D, Confocal Z-projections of geniculate ganglion from 5-HT_3AGFP mice 5 d after FluoroGold injection showing expression of GFP (green) and FluoroGold label (FG; magenta). Arrows indicate double-labeled cells (above threshold in each channel). E, Histograms of GFP and FG normalized fluorescence intensity of individual cells showing bimodal distributions suggestive of a high-expressing population (mean GFP: 0.59, FG: 0.62) and a nonexpressing population (mean GFP: 0.08, FG: 0.08). F, Scatterplot comparing the relative fluorescence intensity for normalized GFP and FG fluorescence. No correlation exists between the two factors (r = 0.35 Pearson's correlation; n = 3 mice, 6 ganglia, 468 cells). Dotted lines (E, F) indicate threshold for each channel. G, Table showing relative number of cells showing suprathreshold expression of GFP and FG label.