Icariin, astragaloside IV and puerarin mixture salvages synaptic loss by enhancing mitochondrial biogenesis: A multi-target strategy for Alzheimer’s disease therapy

OBJECTIVE: This study aimed to elucidate the potential mechanism by which the Icariin, astragaloside IV and puerarin (Ying-Huang-Ge, YHG) mixture regulates mitochondrial-synaptic homeostasis in Alzheimer's disease (AD) MOD mice through the Glycogen Synthase Kinase-3β (GSK-3β)/Peroxisome Proliferator-Activated Receptor γ Coactivator-1α (PGC-1α) signaling axis. METHODS: Thirty 5-month-old male APP/PS1 mice were randomly divided into the MOD group, the YHG treatment group (YHG), and the Donepezil treatment group (DNP) (n = 10 per group). Ten age-matched male C57BL/6 J mice served as the CON group. Following two months of continuous administration, cognitive function was assessed using the Morris Water Maze (MWM) and Novel Object Recognition (NOR) tests. Dendritic spine density in the hippocampal CA1 region was evaluated via Golgi staining, and ultrastructural changes were examined using transmission electron microscopy (TEM). Hippocampal levels of adenosine triphosphate (ATP), malondialdehyde (MDA), and superoxide dismutase (SOD) were measured using biochemical assay kits. Protein expression levels of GSK-3β, p-GSK-3β (Ser9), PGC-1α, mitochondrial functional proteins (NRF-1, TFAM), and synaptic plasticity-related proteins (PSD95, SYN) were determined by Western blot. RESULTS: Compared with the CON group, the MOD group exhibited significantly impaired learning and memory capabilities, reduced dendritic spine density in the hippocampal CA1 region, and disrupted synaptic ultrastructure. Mitochondria displayed pathological changes, including swelling and vacuolization. Furthermore, ATP and SOD levels were significantly decreased, while MDA content was elevated. Western blot analysis revealed increased total GSK-3β expression and significantly decreased expression of p-GSK-3β (Ser9), PGC-1α, downstream mitochondrial biogenesis proteins (NRF-1, TFAM), and synaptic proteins (PSD95, SYN). Intervention with YHG significantly ameliorated these cognitive deficits, mitigated pathological damage to mitochondria and synapses, and reversed the abnormal molecular expression profiles. CONCLUSION: The YHG ameliorates cognitive dysfunction and attenuates synaptic impairment in APP/PS1 mice. The underlying mechanism may involve the inhibition of GSK-3β activity, which subsequently activates PGC-1α-mediated mitochondrial biogenesis, enhances mitochondrial quality, and mitigates oxidative stress, ultimately leading to the restoration of synaptic structural integrity.