Figure 2. The absence of AhR exacerbates adult hippocampal neurogenesis. A, BrdU+ cells in the DG of AhR+/+ and AhR–/– mice measured at p30, p60, and p100 24 h after the last BrdU injection. Two-way ANOVA demonstrated a significant interaction between the age and genotype [F(2, 24) = 9.51; p < 0.05; *, p < 0.05 vs. AhR+/+; n = 5 animals/group]. B, C, Ki67+ cells in the DG of AhR+/+ and AhR–/– mice measured at p30, p60, and p100. Two-way ANOVA demonstrated a significant interaction between the age and genotype [F(2, 28) = 8.56; p < 0.05; *, p < 0.05 vs. AhR+/+; n = 5–6 animals/group]. Representative images of Ki67+ cells in AhR+/+ and AhR–/– mice at different time points are shown in C. D–F, Quantification of the number of nestin/BrdU+ cells by flow cytometry 24 h after BrdU administration. Data are expressed as the percentage of control group (*, p < 0.05 vs. AhR+/+; n = 6 animals/group; D). Representative dot plots of double-stained cells for nestin and BrdU in the DG of AhR+/+ (E) and AhR–/– (F) mice. G–L, Characterization of type-1 (nestin+/GFAP+; G) and type-2 progenitors (nestin+/GFAP-; I) and their proliferative capacity (BrdU+; H and J) in the DG of AhR+/+ and AhR–/– mice determined at p30 and p100. Representative images of nestin (red), GFAP (green), BrdU (gray) of DG of AhR+/+ and AhR–/– mice at p30 (K) and p100 (L; *, p < 0.05 vs. AhR
+/+; #, p < 0.05 vs. AhR–/–; n = 4–6 animals/group). M, N, Quantification of the number of DCX+ cells in the DG of WT and AhR–/– mice (*, p < 0.05 vs. AhR+/+; n = 7–8 animals/group). Representative images of DCX+ cells in AhR+/+ and AhR
–/– mice are shown in N. O, P, Quantification of the number of BrdU+ cells (left) and newborn integrated neurons (BrdU+/Calbindin+; right) determined 28 days after BrdU administration (*, p < 0.05 vs. AhR+/+; n = 7–9 animals/group). Representative colocalization images for BrdU and calbindin in AhR+/+and AhR–/– mice are shown in P. Insets display high-magnification images. Numbers of cells are expressed per 1000 μm2. Data are mean ± SEM. Scale bar is 50 μm in C, J, K, and L; 70 μm in N; and 30 μm in P. Data were compared by using nonparametric 2-tailed Mann–Whitney test in D, M, and O or nonparametric 2-way ANOVA followed by Bonferroni post hoc testing (A, B, G–J).