Shugan granule contributes to the improvement of depression-like behaviors in chronic restraint stress-stimulated rats by altering gut microbiota.

AIM

The investigation aims to evaluate the potential effect of Shugan Granule (SGKL) on the gut, brain, and behaviors in rats exposed to chronic restraint stress (CRS).

METHODS

The fecal microbiota and metabolite changes were studied in rats exposed to CRS and treated with SGKL (0.1 mg/kg/day). Depressive behaviors of these rats were determined through an open-field experiment, forced swimming test, sucrose preference, and weighing. Moreover, LPS-stimulated microglia and CRS-stimulated rats were treated with SGKL to investigate the regulation between SGKL and the PI3K/Akt/pathway, which is inhibited by LY294002, a PI3K inhibitor.

RESULTS

(i) SGKL improved the altered behaviors in CRS-stimulated rats; (ii) SGKL ameliorated the CRS-induced neuronal degeneration and tangled nerve fiber and also contributed to the recovery of intestinal barrier injury in these rats; (iii) SGKL inhibited the hippocampus elevations of TNF-α, IL-1β, and IL-6 in response to CRS modeling; (iv) based on the principal coordinates analysis (PCoA), SGKL altered α-diversity indices and shifted β-diversity in CRS-stimulated rats; (v) at the genus level, SGKL decreased the CRS-enhanced abundance of Bacteroides; (vi) Butyricimonas and Candidatus Arthromitus were enriched in SGKL-treated rats; (vii) altered gut microbiota and metabolites were correlated with behaviors, inflammation, and PI3K/Akt/mTOR pathway; (viii) SGKL increased the LPS-decreased phosphorylation of the PI3K/Akt/mTOR pathway in microglia and inhibited the LPS-induced microglial activation; (ix) PI3K/Akt/mTOR pathway inactivation reversed the SGKL effects in CRS rats.

CONCLUSION

SGKL targets the PI3K/Akt/mTOR pathway by altering gut microbiota and metabolites, which ameliorates altered behavior and inflammation in the hippocampus.