Xiaoyaosan improves depression-like behaviours in mice with post-stroke depression by modulating gut microbiota and microbial metabolism and regulating P2X7R/NLRP3 inflammasome.

Background: Post-stroke depression (PSD) represents the most prevalent complication of stroke and has been reported to be associated with an imbalance in the gut microbiota. Clinically, Xiaoyaosan (XYS) alleviates depressive symptoms in patients with PSD. However, the existing literature does not provide sufficient evidence to ascertain whether XYS can alleviate these symptoms by modulating gut microbiota.

Purpose: This study aims to investigate the potential mechanism of XYS to improve depression-like behavior in mice with PSD by regulating intestinal flora and microbial metabolism.

Study Design: The authors assessed the effect of XYS on the behaviour of PSD mice and evaluated the effects of XYS on structure and metabolism of gut microbiota, the protein expression levels of P2X7 and NLRP3, and associated inflammatory factors in PSD mice. In addition, by performing faecal microbiota transplantation (FMT) on PSD mice with faecal bacteria treated with XYS, the authors further clarified the relationship between intestinal flora disorder, the onset of PSD, and the intervention effect of XYS.

Methods: To investigate the ameliorative effect of XYS on behavioural abnormalities and clarify the important role of intestinal flora regulation in the improvement of PSD by XYS in diseased mice, the authors employed various methodologies, including the PSD model, behavioural tests, haematoxylin and eosin staining, ultrastructural morphology, enzyme-linked immunosorbent assay, western blotting, 16S rRNA sequencing, metabolomic analyses, and FMT.

Results: Oral administration of XYS effectively alleviated depression-like behaviours in PSD mice and repaired the damaged colonic mucosa. XYS inhibited inflammatory factors in serum and hippocampus and regulated the protein expression levels of P2X7 and NLRP3 in the colon and hippocampus of PSD mice. Moreover, XYS restored the gut microbiota and modulated intestinal metabolites in PSD mice. It effectively reduced the abundances of microbes including Ligullacoccus, Streptococcus, and Staphylococcus, while significantly increased the abundances of microbes including Faecalibaculum, Allobaculum, and Monolobus. Furthermore, XYS effectively regulated intestinal metabolites such as methylparaben, valproic acid (Depakene), and disulfiram. More importantly, faecal transplants from the PSD models reproduced depression-like behaviours in normal mice, while XYS-FMT effectively alleviated depression-like behaviours in PSD mice.

Conclusion: Our findings indicate that XYS improves depression-like behaviours in mice with PSD by modulating the gut microbiota and microbial metabolism, and regulating the P2X7R/NLRP3 inflammasome.