Effect of electroacupuncture on metabolic alterations in the hippocampus and dorsal raphe nucleus of Wistar Kyoto rats

Depression is underpinned by a complex pathogenesis that involves the hippocampus and dorsal raphe nucleus (DRN) of the central nervous system. Although electroacupuncture (EA) is proven to be safe and effective for alleviating depression symptoms and causes minimal side effects its underlying therapeutic mechanism remains unclear. In this study, we performed targeted metabolomics to identify metabolite alterations in the hippocampus and DRN of Wistar Kyoto (WKY) rats and elucidate the role and potential mechanism of action of EA. Our results indicated that 3 weeks of consecutive EA significantly ameliorated depression-like behavior in WKY rats. Targeted metabolomics revealed 42 differentially expressed metabolites (DEMs) in the hippocampus and 97 DEMs in the DRN between Wistar and WKY rats. In addition, we observed 19 hippocampal DEMs and 41 DRN DEMs between WKY and EA-treated rats. Subsequent pathway analyses indicated that these DEMs were primarily enriched in amino acid-related metabolic pathways. Moreover, six DEMs were found to be significantly associated with at least one depression-like behavior, indicating their involvement in the pathogenesis of depression. EA intervention modulated the levels of 1-methylhistidine, 3-methylhistidine, carnosine, and riboflavin in depressed rats. Collectively, these findings demonstrate that disturbances in cerebral metabolites, especially amino acids, may be one of the causes underlying depression in WKY rats, and the therapeutic effect of EA is potentially mediated through the modulation of the levels of these metabolites.