Gut microbiota and gut tissue metabolites involved in development and prevention of depression.

Depression is a prevalent, life-threatening, and highly recurrent psychiatric illness. Several studies have shown that depression is associated with endogenous metabolites and the gut microbiota. However, it is unclear whether metabolites in different gut tissues play a role in the pathogenesis of depression and whether the gut microbiota has an impact on depression. Here, we investigated the metabolic signatures in the jejunum, ileum, and colorectum using metabolomics and explored the influence of the gut microbiota on both the development of chronic variable stress (CVS)-induced depression rat model and variations in gut tissue metabolites using a gnotobiotic rat model. The results showed that CVS induced disturbances in gut metabolites (29 differential metabolites) and had different effects on the different segments. When CVS rats were treated with antibiotics, depression-like ethological disorders disappeared, and the decreased catecholamine levels almost normalized. The depression recovery was attributed to the influence of antibiotics on the gut microbiota, especially inhibiting Clostridiaceae (F1), Candidatus arthromitus (G2), Lactobacillus (G6), and elevating Pseudomonadaceae (F6). Moreover, 16 of 29 varied metabolites in CVS rats were reversed with antibiotic treatment. Among them, 12 increased metabolites were decreased, suggesting a trigger for depression. However, four decreased metabolites were increased, indicating a potential therapeutic effect on depression. Based on the Pearson's correlation analysis, hypoxanthine, 3-hydroxypristanic acid, threonic acid, and L-carnitine were strongly associated with F6, F1, G2, and G6, which are involved in the development and prevention of depression. These findings provide a possibility for further exploration of the pathogenesis and prevention of depression.