No effect of running and laboratory housing on adult hippocampal neurogenesis in wild caught long-tailed wood mouse

Background: Studies of adult hippocampal neurogenesis (AHN) in laboratory rodents have raised hopes for therapeutic interventions in neurodegenerative diseases and mood disorders, as AHN can be modulated by physical exercise, stress and environmental changes in these animals. Since it is not known whether cell proliferation and neurogenesis in wild living mice can be experimentally changed, this study investigates the responsiveness of AHN to voluntary running and to environmental change in wild caught long-tailed wood mice (Apodemus sylvaticus). Results: Statistical analyses show that running had no impact on cell proliferation ( p = 0.44), neurogenesis ( p = 0.94) or survival of newly born neurons ( p = 0.58). Likewise, housing in the laboratory has no effect on AHN. In addition, interindividual differences in the level of neurogenesis are not related to interindividual differences of running wheel performance (r(s) = -0.09, p = 0.79). There is a correlation between the number of proliferating cells and the number of cells of neuronal lineage ( rs = 0.63, p < 0.001) and the number of pyknotic cells (r(s) = 0.5, p = 0.009), respectively. Conclusion: Plasticity of adult neurogenesis is an established feature in strains of house mice and brown rats. Here, we demonstrate that voluntary running and environmental changes which are effective in house mice and brown rats cannot influence AHN in long-tailed wood mice. This indicates that in wild long-tailed wood mice different regulatory mechanisms act on cell proliferation and neurogenesis. If this difference reflects a species-specific adaptation or a broader adaptive strategy to a natural vs. domestic environment is unknown.