Schisandrin C alleviates depressive-like behaviors by modulating the AKT/CREB/BDNF pathway, the serotonin pathway of tryptophan metabolism, and the gut microbiota composition

Abstract

Background Schisandrin C (SCC), a bioactive lignan compound derived from Schisandra chinensis (S. chinensis), has been demonstrated to promote intestinal health. However, the antidepressant activity of SCC and its impact on the gut‒brain axis have not been reported. Purpose This study aimed to investigate the antidepressant effects of SCC and elucidate its molecular mechanisms through modulation of the microbiota‒gut‒brain axis. Methods Artificial intelligence (AI)-based target protein prediction, network pharmacology analysis, and experimental validation using intestinal cells, Caenorhabditis elegans, and mice models were conducted. Targeted metabolomics, gut microbiota analyses, and molecular biology techniques were employed for mechanistic elucidation. Results SCC treatment effectively suppressed depressive-like behaviors in mice subjected to chronic unpredictable mild stress (CUMS). SCC upregulated brain-derived neurotrophic factor (BDNF) expression in the brain by regulating the AKT/CREB/BDNF signaling pathway. Additionally, integrated network pharmacology, molecular docking, and metabolomics analyses revealed that SCC significantly increased brain serotonin levels by inhibiting monoamine oxidase (MAO) activity. Furthermore, SCC increased the abundance of Akkermansia and Bifidobacterium, as observed both in the synthetic microbial community in vitro and in the gut microbiota in vivo. Additionally, SCC effectively alleviated intestinal barrier dysfunction and reduced intestinal inflammation in vitro in intestinal cells, in vivo in C. elegans infected with Bacteroides fragilis, and in vivo in the CUMS-induced mice model. Conclusion SCC improves depressive-like behaviors by modulating the microbiota‒gut‒brain axis. These findings underscore the potential of SCC as an effective therapeutic agent for depression.