Treadmill exercise in combination with acousto-optic and olfactory stimulation improves cognitive function in APP/PS1 mice through the brain-derived neurotrophic factor- and Cygb-associated signaling pathways

A reduction in adult neurogenesis is associated with behavioral abnormalities in patients with Alzheimer's disease. Consequently, enhancing adult neurogenesis represents a promising therapeutic approach for mitigating disease symptoms and progression. Nonetheless, non-pharmacological interventions aimed at inducing adult neurogenesis are currently limited. Although individual non-pharmacological interventions, such as aerobic exercise, acousto-optic stimulation, and olfactory stimulation, have shown limited capacity to improve neurogenesis and cognitive function in patients with Alzheimer's disease, the therapeutic effect of a strategy that combines these interventions has not been fully explored. In this study, we observed an age-dependent decrease in adult neurogenesis and a concurrent increase in amyloid-beta accumulation in the hippocampus of amyloid precursor protein/presenilin 1 mice aged 2-8 months. Amyloid deposition became evident at 4 months, while neurogenesis declined by 6 months, further deteriorating as the disease progressed. However, following a 4-week multifactor stimulation protocol, which encompassed treadmill running (46 min/d, 10 m/min, 6 days per week), 40 Hz acousto-optic stimulation (1 hour/day, 6 days/week), and olfactory stimulation (1 hour/day, 6 days/week), we found a significant increase in the number of newborn cells (5 '-bromo-2 '-deoxyuridine-positive cells), immature neurons (doublecortin-positive cells), newborn immature neurons (5 '-bromo-2 '-deoxyuridine-positive/doublecortin-positive cells), and newborn astrocytes (5 '-bromo-2 '-deoxyuridine-positive/glial fibrillary acidic protein-positive cells). Additionally, the amyloid-beta load in the hippocampus decreased. These findings suggest that multifactor stimulation can enhance adult hippocampal neurogenesis and mitigate amyloid-beta neuropathology in amyloid precursor protein/presenilin 1 mice. Furthermore, cognitive abilities were improved, and depressive symptoms were alleviated in amyloid precursor protein/presenilin 1 mice following multifactor stimulation, as evidenced by Morris water maze, novel object recognition, forced swimming test, and tail suspension test results. Notably, the efficacy of multifactor stimulation in consolidating immature neurons persisted for at least 2 weeks after treatment cessation. At the molecular level, multifactor stimulation upregulated the expression of neuron-related proteins (NeuN, doublecortin, postsynaptic density protein-95, and synaptophysin), anti-apoptosis-related proteins (Bcl-2 and PARP), and an autophagy-associated protein (LC3B), while decreasing the expression of apoptosis-related proteins (BAX and caspase-9), in the hippocampus of amyloid precursor protein/presenilin 1 mice. These observations might be attributable to both the brain-derived neurotrophic factor-mediated signaling pathway and antioxidant pathways. Furthermore, serum metabolomics analysis indicated that multifactor stimulation regulated differentially expressed metabolites associated with cell apoptosis, oxidative damage, and cognition. Collectively, these findings suggest that multifactor stimulation is a novel non-invasive approach for the prevention and treatment of Alzheimer's disease.