Xinnaoxin capsule alleviates neuropathological changes and cognitive deficits in Alzheimer's disease mouse model induced by D-galactose and aluminum chloride via reducing neuroinflammation and protecting synaptic proteins

Ethnopharmacological relevance: Originally formulated to mitigate high-altitude sickness, Xinnaoxin capsules (XNX) are composed of three traditional Chinese medicines (Rhodiola rosea L., Lycium barbarum L. and Hippophae rhamnoides) with properties of anti-hypoxia, anti-fatigue, and anti-aging. Emerging evidence now suggests that XNX may also offer therapeutic benefits in Alzheimer's disease (AD), highlighting its potential significance in the development of novel AD treatments.

Aim of the study: This study aims to investigate whether XNX improves AD-related behavioral and cognitive deficits by enhancing antioxidant defenses, reducing peripheral and neuroinflammation, and protecting neurons.

Materials and methods: The AD mouse model was established using D-galactose and aluminum chloride. Spatial memory and anxiety-like behaviors were assessed via the Morris water maze and open field tests to evaluate the therapeutic effects of XNX. Biochemical markers in hippocampal tissue and serum were measured using ELISA kits, while serum chemical composition was analyzed by LC-MS. Histopathological changes and amyloid-β deposition in the hippocampus were examined through hematoxylin-eosin (HE) staining and immunofluorescence. Additionally, hippocampal expression of apoptotic proteins Bax and Caspase-3, anti-apoptotic protein Bcl-2, and synaptic proteins PSD-95 and Syn were assessed via Western blot.

Results: Behavioral tests demonstrated that XNX significantly improved spatial learning and memory abilities, as well as reduced anxiety-like behaviors in AD mice. XNX also modulated inflammatory cytokines and oxidative stress markers in hippocampal tissue and serum, while reducing amyloid-β deposition. Further LC-MS analysis of serum revealed a marked upregulation of compounds such as adenosine following treatment, with key metabolic pathways affected, including linoleic acid metabolism and phenylalanine, tyrosine, and tryptophan biosynthesis. HE staining and immunofluorescence indicated that XNX ameliorated neuronal damage and decreased amyloid-β accumulation. Western blot analysis confirmed that XNX inhibited neuronal apoptosis and preserved synaptic proteins in the hippocampus.

Conclusion: XNX mitigates AD-induced behavioral and cognitive deficits by enhancing antioxidant defenses, reducing peripheral and neuroinflammation, and protecting neurons. Our findings provide valuable data and a theoretical foundation for the potential therapeutic application of XNX in AD treatment and its further development.