A perspective for alzheimer disease from gut microbiota-associated NMR-based fecal metabolomics: a study with 5XFAD mice

Alzheimer’s disease (AD), a neurodegenerative, irreversible, and progressive brain disorder, is characterized by memory loss and cognitive dysfunction. In neurodegeneration, gut microbiota and their metabolites have an impact on behavior and brain function. This study aimed to identify fecal candidate discriminant metabolites in 5XFAD mice assosciated with AD as compared to an age-matched wild-type (WT) healthy mice groups at three different time points (3, 6, and 9 month) using Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy. A total of 18 male mice (n = 9 for 5XFAD mice and n = 9 for WT, with three animals per age group) were used to determine the fecal candidate discriminant metabolites. As a result of the study, it was identified a total of 67 metabolites in fecal samples. Among these, 19 metabolites were found significantly up-regulated or down-regulated in 5XFAD mice compared to WT mice during the disease progress. According to the volcano plot analysis (FC ≥ 1.2 and p-value ≤ 0.05), the potential candidate discriminant metabolites were fumarate and malate in 3-month-old 5XFAD mice, 3-methylxanthine, glucose, cholate, phenylacetate, and trimethylamine N-oxide (TMAO) in 6-month-old 5XFAD mice and cholate and succinate in 9-month-old 5XFAD mice. These findings highlight the potential of fecal metabolomics as a non-invasive exploratory approach for understanding AD disease mechanisms and progression. Furthermore, to the best of our knowledge, this pilot study is the first to utilize NMR spectroscopy to investigate age-stratified cross-sectional changes in fecal metabolites in 5xFAD mice, thereby advancing our understanding of disease progression and potentially informing future therapeutic strategies.