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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., (© 2022 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

• GRb1 activated mitophagy to reduce ROS and decrease astrocytic pyroptosis. • GRb1 enhanced synaptic plasticity by inhibiting astrocytic pyroptosis. • An increase in synaptic plasticity improved depression-like behavior. Astrocytes play a vital role in offering functional support for neurons, which are related to the pathogenic mechanism of depression. Ginsenoside Rb1 (GRb1) is demonstrated with antidepressant-like activities. We aimed to investigate whether GRb1 can inhibit mitophagy-mediated astrocytic pyroptosis to protect neurons in depression. Model rats were subjected to chronic unpredictable mild stress (CUMS) for determining the in vivo antidepressant activity of GRb1. The mitophagy-mediated antipyroptosis role of GRb1 was assessed in lipopolysaccharide (LPS) + ATP-stimulated astrocytes. The mechanism by which GRb1 protects synaptic plasticity was investigated using hippocampal neurons incubated in an astrocyte medium. The rat depressive-like behaviors were determined through sucrose preference, forced swimming, and the open-field tests. Escitalopram was used in the anti-depression control of GRb1. Cyclosporin A (CsA), a mitophagy inhibitor, and interleukin (IL)-1β were used to reverse the role of GRb1 in mitophagy and pyroptosis, respectively. GRb1 inhibited LPS-induced inflammation and activation in the astrocytes and repressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. Also, GRb1 repressed LPS + ATP-promoted astrocytic pyroptosis. During GRb1 treatment, the activation of mitophagy with a decrease in ROS was observed in LPS + ATPs-stimulated astrocytes. CsA enhanced GRb1-decreased ROS and promoted astrocytic pyroptosis. The GRb1-treated astrocyte medium suppressed neuron death and increased neuron viability and synaptic density. Escitalopram and GRb1 improved the depressive-like behaviors of the rats. GRb1 activated mitophagy and inhibited astrocytic activation and pyroptosis in rats with depression. It also reduced impairments in synaptic structures and increased synaptic density in depressive-like rats. IL-1β increased astrocytic pyroptosis and reversed GRb1-enhanced synaptic plasticity in the rats exposed to CUMS. There were no statistical changes in depressive-like behaviors between GRb1 and Escitalopram groups. GRb1 modulates mitophagy and the NF-κB pathway to inhibit astrocytic pyroptosis, thereby maintaining neurological homeostasis by repressing inflammation and enhancing synaptic plasticity. [Display omitted] [ABSTRACT FROM AUTHOR]