Schisandra chinensis ameliorates depressive-like behaviors by regulating microbiota-gut-brain axis via its anti-inflammation activity.

The present study aimed to examine the antidepressant actions of the composition fractions of Schisandra chinensis using LPS-induced mice. Animals were treated with total extracts (SCE), lignans (SCL), polysaccharides (SCPS), and essential oil (SCVO), and then subjected to behavioral tests. The forced swimming test (FST) and tail suspension test (TST) were used as predictive animal models of antidepressant activity. Total extracts and lignans significantly decreased the duration of immobility in FST and TST. We found that treatment with SCE and SCL could significantly decrease the levels of pro-inflammatory cytokines both in the periphery and central nervous system (CNS). This was confirmed by the histopathological examination of the colon. The RT-PCR results demonstrated that SCE and SCL could greatly inhibit the TLR4/NF-κB/IKKα signaling pathway. In addition, the concentrations of Butyric acid and Propionic acid were upregulated by the administration, and the decreased diversity of intestinal microbiota and alterations of the relative proportions of Bacteroidetes and Firmicutes phylum members, Barnesiella and Lactobacillus genus members in LPS-induced mice were restored as well. All results suggested that lignans is the effective fraction of S.chinensis to ameliorating depressive disorders, which its anti-inflammation activity possibly involved in the bidirectional connection between gut microbiota and brain.