A novel Mediterranean diet-inspired supplement reduces hippocampal amyloid deposits and microglial activation through the modulation of the microbiota gut-brain axis in 5xFAD mice.

Neurosyn240 supplementation significantly reduced hippocampal amyloid-β deposits in 5xFAD mice.

• Male and female 5xFAD transgenic mice (n=16 per sex) were randomly assigned to receive either a standard control diet or a diet supplemented with Neurosyn240 for 12 weeks.
• Reduction in amyloid deposits was statistically significant (p<0.05) as assessed by immunofluorescence staining.
• Decreased amyloid deposition was associated with decreased lithocholic acid (LCA) concentrations.
• Hippocampal RNA sequencing highlighted the upregulation of genes involved in promoting amyloid beta clearance mechanisms.

Neurosyn240 supplementation significantly reduced Iba-1 positive microglia in the hippocampus of 5xFAD mice.

• Reduction in Iba-1 positive microglia was statistically significant (p<0.05) as assessed by immunofluorescence staining.
• Decreased microglial activation was associated with increased circulating serotonin levels.
• Statistical analyses were performed using two-way ANOVA to examine the main effects of diet and sex and their interaction.

Neurosyn240 significantly shifted gut microbiome composition in 5xFAD mice.

• Gut microbiota composition was profiled using 16S rRNA amplicon sequencing.
• The shift in gut microbiome composition was associated with downstream changes in circulating metabolites.
• Both male and female mice (n=16 per sex) were included in the analysis, allowing examination of sex-diet interactions.

Neurosyn240 supplementation increased circulating serotonin levels and decreased kynurenine concentrations in 5xFAD mice.

• Serum metabolites were quantified via targeted metabolomics.
• Increased serotonin was specifically associated with the reduction in Iba-1 positive microglia.
• Decreased kynurenine was among the metabolic changes associated with the shifted gut microbiome composition.
• These changes suggest modulation of the tryptophan metabolic pathway.

Neurosyn240 supplementation decreased circulating bile acid concentrations, including TCA, HDCA, TDCA, CDCA, and LCA.

• Five specific bile acids were identified as decreased: taurocholic acid (TCA), hyodeoxycholic acid (HDCA), taurodeoxycholic acid (TDCA), chenodeoxycholic acid (CDCA), and lithocholic acid (LCA).
• Decreased LCA was specifically associated with reduced hippocampal amyloid deposits.
• Bile acid changes were identified via targeted metabolomics of serum samples.

Hippocampal RNA sequencing revealed upregulation of genes involved in amyloid beta clearance mechanisms following Neurosyn240 supplementation.

• Hippocampal gene expression was analysed through both qPCR and RNA sequencing.
• Gene expression changes were consistent with the observed reduction in amyloid deposits.
• Two-way ANOVA was used to examine main effects of diet and sex and their interaction on gene expression outcomes.

The study employed a multi-omics approach in a transgenic mouse model of Alzheimer's disease to investigate microbiota-gut-brain axis mechanisms.

• The 5xFAD transgenic mouse model was used as a model of AD neuropathology.
• Multi-omics approach included 16S rRNA amplicon sequencing, targeted metabolomics, qPCR, and RNA sequencing.
• Both sexes were included (n=16 per sex, 32 total per diet group) and 12-week dietary intervention was employed.
• Neuropathological markers were evaluated using immunofluorescence staining for amyloid-β deposition and Iba-1 positive microglia.