Establishment and Characterization of an Aβ-Related Alzheimer's Disease-like Tree Shrew Model Following...

Alzheimer's disease (AD) is characterized by cognitive decline and amyloid-β (Aβ)-related pathology. Non-rodent models that capture selected aspects of human AD remain limited. We established and characterized a human APP-driven, Aβ-related AD-like tree shrew model following AAV-mediated delivery of triple-mutant human amyloid precursor protein (hAPP-SLA) carrying the Swedish, Austrian, and London mutations by bilateral stereotaxic injection directed at CA1 coordinates. Adult tree shrews received bilateral AAV-hAPP-SLA injections directed at CA1 coordinates and were evaluated by bioluminescence imaging, behavioral testing, PCR, RT-qPCR, Western blotting, ELISA, and histopathology. Vector-associated reporter signals remained detectable for 6 months. The experimental group showed exogenous hAPP expression and reduced endogenous tsAPP expression, increased relative hippocampal Aβ₄₂ protein level, enhanced 4G8-reactive APP/Aβ-related signals, elevated total Aβ immunoreactivity, increased serum Aβ₄₂/Aβ₄₀ ratio, cytoarchitectural alterations, reduced Nissl staining, and Thioflavin S-reactive aggregate-associated signals. AT8 (Ser202/Thr205), GFAP, and Iba-1 immunoreactivity increased, whereas Synaptophysin and PSD-95 immunoreactivity was reduced. These changes were accompanied by reduced short-delay recognition-related performance and reduced social approach and social novelty preference. Aged tree shrews showed partly overlapping alterations. This model provides a non-rodent platform for studying human APP-driven Aβ-related pathology.