Odor Enrichment Increases Hippocampal Neuron Numbers in Mouse

WOS: 000433039400003
PubMed ID: 29731675
The hippocampus and olfactory bulb incorporate new neurons migrating from neurogenic regions in the brain. Hippocampal atrophy is evident in numerous neurodegenerative disorders, and altered hippocampal neurogenesis is an early pathological event in Alzheimer's disease. We hypothesized that hippocampal neurogenesis is affected by olfactory stimuli through the neural pathway of olfaction-related memory. In this study, we exposed mice to novel pleasant odors for three weeks and then assessed the number of neurons, non-neuronal cells (mainly glia) and proliferating cells in the hippocampus and olfactory bulb, using the isotropic fractionator method. We found that the odor enrichment significantly increased the neuronal cell numbers in the hippocampus, and promoted cell proliferation and neurogenesis in the olfactory bulb. In contrast, the glial cell numbers remained unchanged in both of the regions. Our results suggest that exposure to novel odor stimuli promotes hippocampal neurogenesis and support the idea that enriched environments may delay the onset or slow down the progression of neurodegenerative disorders.
Australian Research Council Centre of Excellence for Integrative Brain Foundation (ARC Centre Grant) [CE140100007]; National Health and Medical Research Council Project GrantNational Health and Medical Research Council of Australia [NHMRC APP1086643]
This project was supported by the Australian Research Council Centre of Excellence for Integrative Brain Foundation (ARC Centre Grant CE140100007) and by a National Health and Medical Research Council Project Grant (NHMRC APP1086643). We thank Dr Tim Karl for his suggestions related to the use of odor stimuli and enriched environment.