Figure 2

Voluntary exercise restored functional adult neurogenesis in the DG of Ts65Dn mice. (A) Schematic representation of the experimental protocol and BrdU administration to label proliferating cells. (B) Representative confocal z-stack projection images showing immunostaining for BrdU (green), DCX (red) and the pan-neuronal marker NeuN (blue). Scale bar: 50 µm. The insert on the upper-left corner of each image shows a detail of BrdU staining in the area indicated by the dashed rectangle. (C) Quantitative analyses of BrdU⁺ cells found 24 h post BrdU administration in sedentary or running Ts65Dn and WT mice. Proliferation of neural precursor cells was fully rescued by exercise in Ts65Dn mice. Two-way ANOVA: genotype [F _1,23 = 10.967, P = 0.003]; treatment [F _1,23 = 11.391, P = 0.003]; genotype x treatment [F _1,23 = 0.0000291, P = 0.996]. (D) Quantitative analysis of DCX⁺ cells in sedentary or running Ts65Dn and WT mice. Numbers of DCX⁺ immature newborn neurons were totally restored in Ts65Dn mice by running. Two-way ANOVA: genotype [F _1,23 = 10.244, P = 0.004]; treatment [F _1,23 = 10.480, P = 0.004]; genotype x treatment [F _1,23 = 0.0455, P = 0.833]. (E) Schematic representation of the experimental protocol for BrdU pulse-chase experiments. (F) Representative confocal z-stack projection images showing immunostaining for BrdU (green), NeuN (red) and GFAP (blue) on brain slices from mice sacrificed 4 weeks after BrdU administration. Scale bar: 50 µm. (G) The number of new neurons (BrdU⁺/NeuN⁺) found 4 weeks after BrdU administration was rescued by exercise in Ts65Dn mice. Two-way ANOVA: genotype [F _1,27 = 5.123, P = 0.032]; treatment [F _1,27 = 22.833, P < 0.001]; genotype x treatment [F _1,27 = 4.871, P = 0.036]. (H) Percentage distribution of BrdU⁺/NeuN⁺, BrdU⁺/GFAP⁺, and BrdU⁺ only-labeled cells found 4 weeks after BrdU administration. No statistical difference was found between the experimental groups. (I) Schematic representation of the experimental protocol and positioning of stimulating and recording electrodes in hippocampal circuit for DG-LTP. (J) Average time course of the increase in the slope of field excitatory postsynaptic potentials (fEPSP) elicited in the DG medial molecular layer after stimulation of the MPP in hippocampal slices obtained from Ts65Dn and WT mice. (K) Quantification of LTP elicited in the DG of WT and Ts65Dn mice. Two-way ANOVA: genotype [F _1,23 = 60.530, P < 0.001]; treatment [F _1,23 = 79.844, P < 0.001], genotype x treatment [F _1,23 = 15.859, P < 0.001]. Number in parenthesis indicates the number of samples analyzed for each experimental group. *P < 0.05, **P < 0.01, ***P < 0.001, Tukey post hoc test following two-way ANOVA.