Electroacupuncture alleviates comorbid obesity and depression via the gut-brain axis: orchestrating SCFA-producing bacteria and hippocampal synaptic plasticity.

INTRODUCTIONComorbid obesity and depression (COMBD) represents a complex metabolic-neuropsychiatric challenge with limited therapeutic options. While Electroacupuncture (EA) is effective for both metabolic and mood disorders, the systemic mechanisms-particularly the interplay between the gut microbiome and hippocampal plasticity-remain elusive.

METHODSWe established a COMBD rat model using a high-fat diet combined with chronic unpredictable mild stress (CUMS). An integrated multi-omics approach comprising 16S rDNA sequencing, LC-MS/MS serum metabolomics, and hippocampal transcriptomics was utilized to decipher the therapeutic mechanisms of EA.

RESULTSEA treatment significantly attenuated body weight gain and reversed depressive-like behaviors. Crucially, EA restructured the dysbiotic gut microbiota, specifically increasing the abundance of short-chain fatty acid (SCFA)-producing bacteria. This microbial restoration was strongly correlated with a reprogrammed serum metabolic profile. In the hippocampus, transcriptomic analysis identified Cd74 as a pivotal upstream regulator modulated by EA. Furthermore, EA mitigated hippocampal oxidative stress and restored synaptic plasticity, evidenced by increased dendritic spine density and upregulated synaptic protein expression.

CONCLUSIONOur findings suggest that EA ameliorates COMBD via a coordinated "Microbiota-Metabolism-Brain" axis. Specifically, EA creates a neuroprotective milieu by promoting beneficial SCFA-producing bacteria and regulating metabolic signals, which subsequently targets hippocampal Cd74 to restore synaptic plasticity. This study provides a novel mechanistic basis for the clinical application of EA in treating complex metabolic-mood comorbidities.