Linggui Zhugan decoction as a potential medicine for neuroprotection in Alzheimer's disease via AMPK pathway

Alzheimer's disease (AD) is a degenerative dementia illness that causes atrophy of the temporal and frontal lobes of the cerebral cortex. Linggui Zhugan (LGZG), a classic Chinese herbal formula, was initially recognized as a safe and effective treatment of cardiovascular diseases for long history. This study intended to assess the effects and the molecular mechanism of LGZG on AD progress. C57BL/6 mice were divided into six groups: normal mice, amyloid precursor protein/presenilin 1 (APP/PS1) mice (model group), positive control group (model mice treated with donepezil), high, medium and low LGZG group (model mice treated with 7g/kg/d, 3.5g/kg/d or 1.75g/kg/d LGZG respectively). Water maze results showed that the escape latency and path length of high and medium LGZG groups declined compared to the model mice, the decline degree was dose-dependent. The hippocampal slices of six groups were analyzed by Nissl-staining, Perls' iron staining and immunofluorescence assay. The results indicated LGZG could restore morphological anomalies and alleviate iron deposition of AD mice, and the GXP4 positive cells increased significantly. The MDA, Fe2+ and GSH were measured by biochemical testing, whose results illustrated that LGZG could normalize MDA, Fe2+ and GSH levels in AD model compared to un-treated APP/PS1 model. The higher dose of LGZG the mice received, the more intensive effects on those levels of molecules. Western blot results showed that LGZG could affect NeuN, AMPK, p53, SLC7A11 and GPX4 levels in the hippocampus of AD model, which was all proteins related to AMPK pathway. In conclusion, LGZG has a neuroprotective effect on AD through AMPK pathway by alleviating oxidative stress and ferroptosis.