Multi-omics analysis reveals mechanisms of FMT in Enhancing antidepressant effects of SSRIs.

Objective: This study explores the behavioral and molecular biological impacts of Fecal Microbiota Transplantation (FMT) on depressive mice unresponsive to treatment with Selective Serotonin Reuptake Inhibitors (SSRIs).

Methods: Healthy male C57BL/6 mice were used to establish a depression model through chronic restraint stress, treated with fluoxetine, and categorized into Response and Non-response groups. An FMT treatment was added to the Non-response group. Behavioral tests were conducted to assess symptoms of depression. The gut microbiome, plasma metabolites, and hippocampal tissue gene expression and function changes were analyzed using 16S rRNA gene sequencing, LC-MS, and RNA sequencing.

Results: FMT significantly improved the depressive symptoms in SSRIs-resistant mice. There was a partial restoration in the diversity and structure of the gut microbiota in the FMT group. Compared to the Non-response group, significant changes were noted in the metabolomic profiles of the FMT group, identifying various differential metabolites. Functional annotations indicated that these metabolites are involved in multiple metabolic pathways. In the Non-response group, certain gene expression levels were significantly restored. GO and KEGG enrichment analyses revealed that these differential genes mainly involve cytokine activity, receptor signaling regulation, and NOD-like receptor signaling pathways. Joint analysis suggested that FMT may exert its effects through an increase in the abundance of g__Paraprevotella, leading to decreased baicalin content and increased Tal2 expression.

Conclusion: FMT has potential in improving depressive symptoms unresponsive to SSRIs treatment. Its mechanism may be related to the modulation of the gut microbiota and its metabolites, subsequently affecting gene expression.