Alisol A ameliorates vascular cognitive impairment via AMPK/NAMPT/SIRT1-mediated regulation of cholesterol and autophagy.

Abstract

Atherosclerosis-related vascular cognitive impairment (VCI) is associated with dysregulated cholesterol metabolism and impaired autophagy. Alisol A, a natural tetracyclic triterpenoid derived from the traditional ZeXieYin Formula, has demonstrated anti-atherosclerotic and neuroprotective effects. However, its role in modulating brain cholesterol homeostasis and mitophagy in VCI remains largely unexplored. Methods: To elucidate the mechanism of Alisol A and evaluate its translational relevance, we employed an Ldlr^-/- mouse model of VCI induced by a high-fat diet and left common carotid artery ligation. Alisol A was administered intragastrically, and cognitive function was assessed using the Morris water maze, Y-maze, and novel object recognition tests. To probe the role of NAMPT, pharmacological inhibition and lentiviral overexpression strategies were applied. Mechanistic investigations included Western blotting, immunofluorescence, and transmission electron microscopy to examine cholesterol metabolism, oxidative stress, mitophagy, and synaptic plasticity. Additionally, molecular docking, surface plasmon resonance, and lipidomic profiling were used to explore Alisol A-NAMPT binding and downstream regulatory pathways. Results: Alisol A significantly ameliorated cognitive impairment in Ldlr^-/- mice. Mechanistically, it restored cholesterol homeostasis by activating the AMPK/NAMPT/SIRT1 signaling axis, upregulated UCP2 to suppress oxidative stress, and inhibited glial activation, thereby preserving neuronal structure and function. Additionally, Alisol A reactivated mitophagic flux by enhancing PINK1/PARKIN signaling and facilitating the clearance of damaged mitochondria, ultimately improving mitochondrial function. NAMPT was identified as a key molecular target mediating these neuroprotective effects. Conclusion: Alisol A confers neuroprotection in VCI by regulating cholesterol metabolism, attenuating oxidative stress, and restoring mitophagy via NAMPT-mediated signaling. These findings highlight its therapeutic potential in atherosclerosis-related cognitive decline.