Neuroinflammation is closely linked to the pathogenesis of Alzheimer's disease (AD) and the associated deficits in learning and memory. Microglial activation serves as a central mediator of this inflammatory response. While previous studies have shown that aerobic exercise exerts protective effects by suppressing microglial activation and attenuating neuroinflammation, the underlying mechanisms remain largely unclear. Notably, INPP5D, an immunoregulatory factor predominantly expressed in microglia, is closely associated with aberrant microglial activation and cognitive decline in AD. Elucidating the role of INPP5D in microglial regulation and anti-inflammatory processes during aerobic exercise may uncover novel therapeutic targets for early cognitive impairments in AD. Male 5 ×FAD mice underwent treadmill training to evaluate the effects of aerobic exercise. Before training, recombinant adeno-associated virus (rAAV) encoding INPP5D was injected into the hippocampus to induce overexpression. Treadmill exercise commenced 21 days post-injection, once viral expression was established. Viral expression was confirmed via immunofluorescence staining and Western blot analysis. Cognitive function was assessed using the novel object recognition test and the Morris water maze (MWM). Hippocampal Aβ deposition was examined through immunohistochemical staining. Levels of neuroinflammatory markers in the hippocampus and serum were quantified using enzyme-linked immunosorbent assay (ELISA). Microglial activation was evaluated by immunofluorescence staining. The interaction between INPP5D and TREM2, as well as TREM2 expression, was analyzed using co-immunoprecipitation and Western blotting. Additionally, the expression of cGAS and STING proteins was determined by Western blotting. Aerobic exercise improved learning and memory impairments in 5 ×FAD mice through the regulation of INPP5D, leading to reduced Aβ deposition in the hippocampus and attenuation of neuroinflammation in both the hippocampus and serum. It also modulated microglial activation in the hippocampus. Moreover, aerobic exercise upregulated TREM2 expression by regulating INPP5D and suppressed activation of the cGAS-STING inflammatory pathway. This study demonstrates that aerobic exercise alleviates neuroinflammation and improves early learning and memory impairments in AD by modulating microglial activity through INPP5D. These findings offer new insights into the underlying mechanisms by which aerobic exercise mitigates neuroinflammation in AD, highlighting its therapeutic potential.

Working memory deficits, one of the earliest hallmarks of Alzheimer’s disease (AD), are closely linked to abnormal neural activity in the dorsolateral prefrontal cortex (DLPFC). Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation therapy, has been shown to ameliorate early AD working memory deficits by modulating excitatory activity in the DLPFC, yet the underlying mechanisms remain incompletely understood. This investigation was structured around 3 experimental phases. We initially applied tDCS to stimulate the left prefrontal cortex (PFC) of transgenic mice with 5 familial AD (5×FAD) 5 d per week for 4 weeks. Subsequently, we employed optogenetic (Opt) techniques to modulate left PFC glutamatergic neurons. Finally, we inhibited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) expression in the left PFC to elucidate the essential function of SNARE complex assembly with chaperone molecules in orchestrating synaptic vesicle release. tDCS treatment improved working memory deficits in early-stage AD mice. This was accompanied by increased cerebral blood flow, enhanced neuronal excitability, amelioration of neurochemical metabolic disorders, and reduced amyloid β-protein (Aβ) deposition in the left PFC. Opt stimulation of PFC glutamatergic neurons similarly improved working memory, indicating the association between tDCS’s therapeutic effects and synaptic plasticity of excitatory neurons. Crucially, tDCS facilitated synaptic vesicle fusion and release, evidenced by increased vesicle numbers, enhanced release probability, improved synaptic transmission efficacy, and upregulation of the SNARE complex, Snap25, and Syt1. Inhibiting SNARE expression in the left PFC attenuated the tDCS-induced improvements in synaptic vesicle release and working memory. These findings collectively demonstrate that left PFC-targeted tDCS modulates interactions between the SNARE complex and chaperone molecules, thereby promoting synaptic vesicle fusion and release. This mechanism underlies the amelioration of early AD-like working memory impairment by tDCS.

Cognitive frailty (CF), characterized by concurrent cognitive and motor decline, is a major challenge to healthy aging, yet effective interventions remain limited. Klotho, an anti-aging protein that declines with age, has been implicated in both hippocampal function and skeletal muscle homeostasis. In this study, we investigated whether aerobic exercise combined with multisensory stimulation training (CT) ameliorates age-related CF through systemic Klotho signaling. A 16-month-old mouse model of age-related CF was assigned to aerobic training, multisensory stimulation, or combined training, and behavioral, electrophysiological, histological, and molecular assessments were performed. To examine the mechanistic role of Klotho, dual-route shRNA delivery was used to inhibit systemic Klotho expression. CT significantly improved cognitive and motor performance compared with either intervention alone. CT also increased hippocampal dendritic spine density and long-term potentiation, reduced collagen deposition in gastrocnemius muscle, and upregulated Klotho, FGF19, and FGFR1 expression in both hippocampus and muscle, accompanied by elevated serum Klotho levels. Klotho knockdown attenuated these beneficial effects, reduced PSD95 and GluN2B expression, and increased MuRF3 and TNF-α levels. These findings suggest that CT alleviates cognitive frailty and that systemic Klotho is a key mediator linking hippocampal synaptic function and skeletal muscle homeostasis.