Exercise by Shaking Alleviates the Decline in Memory due to Aging: A Study in Mice

Introduction: Although exercise can prevent cognitive decline due to aging, few elderly individuals are able to exercise for long. Therefore, an exercise method for older adults that is feasible for a long duration without overexertion is necessary. In this study, we focused on exercise by shaking. This study examined the possibility to prevent the decline in memory through regular and long-term shaking exercise using a senescence-accelerated mouse (SAM) model. Behavioral analysis was conducted, and histological changes in the mouse brain were examined to evaluate whether this stimulation method could become a novel exercise method. Materials and Methods: The shaking exercise was applied to SAMP10 mice for 30 min 3 times per week for 25 continuous weeks. Behavioral analysis included a step-through passive avoidance test, whereas the histological analysis involved immunohistochemical staining using the anti-glutamate receptor (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors [AMPAR]) antibody in the hippocampus. The number and area of nerve cells in the hippocampal regions were measured and compared between groups. Results: Behavioral analysis revealed that the shaking group retained memory longer than the control group, and memory capacity decline was suppressed. Additionally, histological examination showed that the shaking group had a higher number of AMPAR receptor-positive neurons per area in the hippocampal CA1 and CA3 regions than the control group, suggesting that degeneration and shedding of neurons due to aging was suppressed. Discussion/Conclusion: We believe that shaking could become an exercise therapy that can reduce the decline in memory with aging and expect its human application in the future.