Reduced BDNF levels affect cell survival and exercise-mediated cell proliferation. A - D, Photomicrographs of BrdU+ cells 1 day after BrdU injection in the DG of WT (Aand B) and cKO (Cand D). The mice were maintained in either standard (Aand C) or enriched conditions (Band D). Green or yellow, BrdU+ cells; Red, NeuN+ cells. Scale bar: 100 μm. E, Quantification of BrdU+ cells (Mean ± SEM; 6-12 animals/group). *, P < 0.05; **, P < 0.01. F, Quantification of BrdU+ cells after sub-grouping the EE groups into low-activity and high-activity groups. *, P < 0.05. G - H, Photomicrographs of Ki67+ cells in the DG of WT (G) and cKO-T50 (H) mice in standard condition. Scale bar: 100 μm. I, Quantification of Ki67+ cells in cKO-T50 and control littermates (Mean ± SEM; 8 animals/group).