Gastrodin combined with donepezil alleviates cognitive dysfunction in Alzheimer’s disease mice by improving mitochondrial function through AMPK/PGC-1α/SIRT3 axis

Objective This study aims to explore whether gastrodin (Gas) combined with donepezil (Don) has a neuroprotective effect on Alzheimer’s disease (AD) mice by regulating the AMPK/PGC-1α/SIRT3 signaling axis. Methods HT22 cells were transfected with SIRT3 siRNA or control siRNA. Cells were then treated with the AMPK inhibitor, Don, Gas, or their combination. Subsequently, HT22 cells were treated with Amyloid beta 1–42 (Aβ 1–42) to induce an in vitro AD model. Cell viability was detected by CCK8 assay. DCFH-DA fluorescent probe was used to evaluate cell reactive oxygen species (ROS). Adenosine triphosphate (ATP) content was detected by luciferase chemiluminescence method. Cell membrane potential was measured by flow cytometry. For in vivo experiments, WT mice and APP/PS1 mice were treated with Don, Gas or a combination of drugs. Morris water maze test, Y-maze test and novel object recognition test were used to evaluate the cognitive impairment of mice. The pathological changes of hippocampus were detected by HE staining, and the expression of Aβ protein in hippocampus and cortex was detected by IHC. In addition, the protein and mRNA expressions of APP, Tau, and AMPK/PGC-1α/SIRT3 signaling axis were determined by Western blot and RT-QPCR. Results Gas combined with Don significantly improved cognitive dysfunction, reduced Aβ plaque deposition in the cortex and hippocampus, up-regulated AMPK/PGC-1α/SIRT3 axis, and inhibited the abnormal phosphorylation of Tau and APP in APP/PS1 mice compared with the model group and the Don group ( p < 0.05). In vitro cell experiments confirmed that the combination of the two drugs could improve cell viability, inhibit cell apoptosis, restore ATP level, reduce ROS accumulation, stabilize mitochondrial membrane potential, and improve mitochondrial function ( p < 0.05). Molecular experiments and complementary experiments showed that Gas combined with Don activated AMPK/PGC-1α/SIRT3 signaling axis ( p < 0.05). Silencing SIRT3 or inhibiting AMPK could reverse the protective effect of the combined regimen ( p < 0.05). Conclusion Gas combined with Don can maintain mitochondrial homeostasis through AMPK/PGC-1α/SIRT3 pathway, alleviate AD-relaated pathological damage, and exert neuroprotection.