Skip to main content
. 2017 Dec 6;37(49):11967–11978. doi: 10.1523/JNEUROSCI.1668-17.2017

Figure 1.

Figure 1.

Loss of Freud-1 in 5-HT neurons increases 5-HT1A autoreceptors. A, Conditional KO strategy. To delete Freud-1 in 5-HT neurons, the cF1ko mouse was generated by crossing Cc2d1a(Freud-1)flx/flx mice with TPH2-CreERT2 mice. At 8 weeks of age, mice were administered tamoxifen to activate CreERT2-induced recombination. To delete both Freud-1 and 5-HT1A autoreceptors in 5-HT neurons, the cF1ko mice were mated to the 5-HT1Aflx/flx mice, in which the 5-HT1A gene is flanked by LoxP sites and a YFP cassette to generate the Freud-1/5-HT1A double KO mice following tamoxifen administration. B, Tamoxifen-induced recombination specificity. Hippocampal and prefrontal cortex sections from tamoxifen-treated conditional Freud-1 KO/ROSA-GFP mice (cF1KO) show background GFP staining. C, Tamoxifen-induced recombination and loss of Freud-1 in DR. DR sections from tamoxifen-treated cF1KO mice were stained for GFP and either TPH or Freud-1 (10× magnification). Scale bar, 20 μm; inset, 20×. GFP was present in 92% of TPH+ cells, whereas 88% of Freud-1 was in GFP− cells in cF1KO sections (n = 4). D, Loss of Freud-1 in 5-HT neurons. Freud-1/TPH-labeled cells in DR were almost absent in cF1ko compared with WT. By contrast, Freud-1+/TPH− cells remained (white arrowheads) (n = 4). E, Quantification of GFP-, TPH-, and Freud-1-stained cells in DR of cF1KO and WT mice (n = 4), shown as mean ± SE (p < 0.001). F, Quantification of 5-HT1A-, TPH-, and Freud-1-stained cells in DR of cF1ko (non-ROSA-GFP) and WT mice (n = 4), shown as mean ± SE (p < 0.001). G, Loss of Freud-1 and increased 5-HT1A+ cells in DR of cF1ko mice. DR sections from tamoxifen-treated cF1ko versus F1wt (WT) mice (Scale bar, 50 μm; n = 4) were stained for TPH and 5-HT1A receptors (arrow, 5-HT1A in TPH− cells); 5-HT1A receptors were increased in TPH+ cells. H, Increased 5-HT1A binding in raphe of cF1ko mice. Left, Representative images of 125I-MPPI autoradiography of sections from cF1ko and WT mice in dorsal and median raphe (boxes) at two levels (bregma −4.60 and −4.72 mm) and hippocampus (bregma −1.70). Right, Quantification of 125I-MPPI binding. Data are mean ± SEM (n = 4/group). *p < 0.05. **p < 0.01. 5-HT1A binding was increased in raphe of cF1ko mice: DR (unpaired two-tailed Student's t test, df = 6, t = 9.129, ***p < 0.001), MR (unpaired two-tailed Student's t test, df = 6, t = 6.635, *p < 0.05).