Effect of X-ray irradiation on fluoxetine-induced adult neurogenesis and dematuration in the DG. (A) Experimental scheme. Mice were irradiated with X-rays (10 Gy) 14 days before initiation of fluoxetine treatment (ip, intraperitoneally injected). Mice were sacrificed 24 h after the final drug treatment. (B and C) Representative images of DCX (B) and calbindin (C) immunohistochemistry. Scale bars: 100 μm. (D) Quantification of calbindin-IR signal intensity in the GCL and the ML in control (Sham) and X-ray-irradiated mice. Data are expressed as the mean ± SEM (n =5 or 6). Main effect of drug: P < 0.0001 (GCL), P < 0.0001 (ML); main effect of X-ray irradiation: P = 0.0303 (GCL), P = 0.0087 (ML); interaction of drug and X-ray irradiation: P = 0.1089 (GCL), P = 0.2085 (ML); P values determined by two-way ANOVA.