Protective effects of different exercise modalities in an Alzheimer's disease-like model

Our aim was to investigate the probable protective effects of aerobic, resistance and combined exercise methods on ovariectomy and d-galactose induced Alzheimer's Disease (AD)-like model. d-galactose (100mg/kg) or saline were administered intraperitoneally for 6 weeks to ovariectomized or sham-operated rats (n=8/group). Aerobic (AE), resistance (RE) and combined exercises (CE) (aerobic+resistance) were performed for 3 times a week for 6 weeks. Anxiety level and cognitive functions were evaluated via hole-board and object recognition tests. Brain myeloperoxidase, malondialdehyde, nitric oxide activity, lucigenin-enhanced chemiluminescence, glutathione and serum insulin like growth factor-I (IGF-I) assays were done. Hippocampal mRNA levels of nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), and amyloid precursor protein 695 (APP695) were measured. Amyloid Beta (Aβ), NGF, BDNF, IGF-I immunoreactive neurons were evaluated. Freezing time were increased in AD-like model and decreased back with AE (p<0.05). Deteriorated working memory in AD-like model was improved with all exercise types (p<0.05-0.001). Reduced glutathione levels in AD-like model were increased and increased malondialdehyde levels were reduced and serum IGF-I levels were increased by all exercises (p<0.05-0.001). Increased APP mRNA levels in AD-like model were decreased via CE (p<0.05). Elevated Aβ scores in AD-like model were decreased by RE and CE (p<0.01) in hippocampus and by all exercise types in cortex (p<0.05-0.01). Decreased cortical NGF immunocytochemical scores of AD-like model were increased by CE (p<0.05). Different exercise models may have protective effects in development stage of AD via reducing oxidative stress and Aβ scores, and by improving antioxidant system and brain plasticity.