Figure 4

Exercise decreases the hippocampal neuronal loss in the CA1 area of Tg4-42^het and Tg4-42^hom mice and increases neurogenesis in Tg4-42^hom mice. (a) Schematic drawing of the counting area (modified from Paxinos and Franklin³⁴). (b) Design-based stereology was performed to determine the number of CA1 pyramidal cells in 12-month Tg4-42^het and 6-month Tg4-42^hom mice. Significantly increased neuron numbers could be detected in enriched environment (EE) Tg4-42^het and Tg4-42^hom mice (+12.8% and +14.4%, respectively) compared with standard housing (SH) littermates. (c) No CA1 volume differences could be detected between SH and EE Tg4-42^het and Tg4-42^hom mice. (d) Tg4-42^hom mice with access to a free wheel showed a 16.5% increased CA1 neuron number compared with animals with blocked wheel cages, but (e) no volume difference. (f, h) Quantification of dentate gyrus (DG) granule cells revealed no differences between SH and EE Tg4-42^het mice, while EE Tg4-42^hom mice displayed significantly higher granule cell numbers in the DG compared with SH controls. (g, i) Quantification of doublecortin (DCX)-positive neurons in the subgranular zone of the DG revealed no increased neurogenesis in 12-month Tg4-42^het mice upon EE housing. In contrast, 6-month Tg4-42^hom EE mice showed a 32.6% increase of subgranular DCX-positive neurons compared with Tg4-42^hom SH mice. All data were given as means±s.e.m. ***P<0.001; **P<0.01.