Beneficial Effects of the Herbal Medicine Zuo Gui Wan in a Mice Model of Alzheimer's Disease via Drp1-Mediated Inhibition of Mitochondrial Fission and Activation of AMPK/PGC-1α-regulated Mitochondrial Bioenergetics.

Ethnopharmacological Relevance: Zuo Gui Wan (ZGW) is a well-known traditional Chinese medicine decoction used for approximately 400 years to treat age-related degenerative conditions, including cognitive impairment in older adults, osteoporosis, and general aging. However, the mechanism of action for ZGW remains unclear.

Aims Of The Study: This study aims to investigate the efficacy of ZGW in improving cognitive function in Alzheimer's disease (AD) animal models and to explore the underlying mechanisms, presenting a novel perspective in the field.

Materials And Methods: Six-month-old male APP/PS1 mice were divided into three groups that received either metformin (200 mg/kg daily) or ZGW (6 and 12 g/kg daily). High-performance liquid chromatography was conducted for ZGW's quality control. Cognitive function was assessed using the Morris water maze test. Neuronal loss, synaptic plasticity, and β-amyloid (Aβ) deposition were evaluated through Western blot or immunofluorescence staining. The underlying molecular mechanisms were investigated using ELISA, Western blot, qRT-PCR, co-immunoprecipitation assay, ATP assay, and cytochrome c oxidase assay.

Results: ZGW, administered in both low and high doses, significantly enhanced cognitive performance, notably decreased neuronal loss and Aβ deposition, and reduced levels of Aβ1-40/42. It also inhibited excessive mitochondrial division primarily by suppressing phosphorylated Drp1, especially at high doses of ZGW. Co-immunoprecipitation experiments further confirmed that ZGW inhibited the interaction between Aβ and p-Drp1. Furthermore, similar to the effects of the AMPK activator metformin, ZGW led to a marked increase in the mitochondrial DNA copy number and upregulated the AMPK/PGC-1α/NRF1/TFAM pathway. Improvements in mitochondrial function were evident from the increased ATP production, elevated expression of SOD2, and upregulated cytochrome c oxidase activity. Additionally, the excess byproduct of reactive oxygen species, 4-HNE, decreased in the group treated with ZGW.

Conclusion: This study provides compelling evidence that ZGW improves cognitive impairment in APP/PS1 mice by activating AMPK/PGC-1α-regulated mitochondrial bioenergetics and inhibiting Aβ-induced mitochondrial fragmentation, highlighting its potential as an effective therapeutic strategy for AD.