Effect of Water Temperature during Aquatic Exercise on Cognitive Impairment in Mice with Chronic Cerebral Hypoperfusion.

Introduction: Given the lack of effective pharmacotherapy for vascular dementia (VaD) and the reported benefits of exercise, this study examined the impact of water temperature during aquatic exercise (AE) on cognitive and pathological outcomes in a mouse model of VaD. METHODS: Twelve-month-old male mice underwent bilateral common carotid artery stenosis (BCAS) to induce chronic cerebral hypoperfusion. Groups included sham, BCAS control (no exercise), and BCAS mice assigned to AE in water baths at 25°C, 30°C, or 35°C. Cognitive performance was assessed using the elevated plus maze, Y-maze, and novel object recognition test (NORT). Brain tissues were analyzed for microglial marker CD68, astrocytic marker GFAP, and myelin basic protein (MBP) in the corpus callosum. RESULTS: The 30°C AE group showed the greatest improvement in NORT performance and swim activity. CD68 expression was unchanged across groups, but GFAP expression was significantly reduced at 30°C, suggesting suppressed astrocyte activation. Furthermore, the decline in MBP expression after BCAS was attenuated in this group, indicating preserved white matter integrity. CONCLUSION: AE at approximately 30°C alleviated cognitive deficits in a VaD model, likely by reducing neuroinflammation and protecting myelin. These findings highlight the therapeutic potential of optimizing AE conditions, particularly water temperature, for dementia-related rehabilitation.

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