Forced treadmill running and ladder climbing physical activity attenuates cognitive decline and protein aggregates in aged 3xTg-AD mice.

Alzheimer's disease (AD) is characterized by a progressive cognitive decline and pathological cascade involving amyloid-β (Aβ) plaque, hyperphosphorylated tau (pTau), neuroinflammation, and neurodegeneration. Although anti-amyloid antibody therapies have recently been approved, their clinical benefits remain limited and often accompanied with significant adverse effects. Physical activity has emerged as a promising non-pharmacological intervention for AD, with both aerobic and resistance physical activity showing beneficial effects in preclinical studies. However, the effects of different types of physical activity remain insufficiently understood. In this study, we investigated the effects of a forced treadmill running and ladder climbing physical activity procedure on cognitive behaviors, gliosis, and protein aggregate pathology in aged 3xTg-AD mice. Thirteen to fourteen months old 3xTg-AD mice were subjected to a six-week forced treadmill running and ladder climbing physical activity protocol. Cognitive functions were evaluated using the novel object recognition, Y-maze, and social behavior tests. Hippocampal and cortical tissues were analyzed by immunostaining for Aβ, pTau, Glial Fibrillary Acidic Protein (GFAP), Ionized Calcium-Binding Adapter Molecule 1 (IBA1), and inhibitory neuron markers. Our study demonstrated that the six-week forced treadmill running and ladder climbing physical activity procedure reduced age-associated cognitive declines in spatial working memory, object recognition memory, and sociability in aged 3xTg-AD mice. Such physical activity procedure also reduced Thioflavin S (Thio S) labeled misfolded protein aggregates and reactive gliosis in the cortex and/or hippocampus. Notably, forced treadmill running and ladder climbing physical activity procedure decreased Thio S positive neuropathology within somatostatin-positive interneurons of the hippocampus and cortex, indicating a cell-specific neuroprotective effect. Our results demonstrated that forced treadmill running and ladder climbing physical activity procedure produced significant behavioral and neuropathological benefits in aged 3xTg-AD mice, supporting physical activity as a promising non-pharmacological intervention for modulating gliosis and protein aggregate pathology in aging and AD.