Xuefu Zhuyu Capsule alleviates depression in post-stroke depression model rats <i>via</i> modulation of the gut microbiota–gut–brain axis

Xuefu Zhuyu Capsule (XFZY) demonstrated potential in alleviating post-stroke depression (PSD), a condition whose underlying mechanisms may involve the gut-brain axis. This study aimed to explore the therapeutic effects of XFZY on PSD and its possible modulation of the gut microbiota-gut-brain axis in a rat model. Wistar rats were randomly assigned to sham, PSD, three XFZY dose (0.216, 0.432, 0.864 g/kg), and fluoxetine (1.80 mg/kg) groups (n = 12 per group). The PSD model was established using transient middle cerebral artery occlusion (t-MCAO) combined with chronic unpredictable mild stress (CUMS), followed by 28 days of XFZY administration. In a separate experiment, gut microbiota was depleted via antibiotic cocktails, with rats divided into sham, PSD, XFZY medium Dose (XFM), pseudo-germ-free (PGF) and PGF + XFM (PGFX) groups. Behavioral tests indicated that XFZY ameliorated depressive-like behaviors, with the medium dose (0.432 g/kg) showing the most significant effect. Histological analysis using hematoxylin and eosin (H&E) and Nissl staining revealed that XFZY alleviated colonic and neuronal damage. Furthermore, 16S rRNA sequencing and gas chromatography revealed that XFZY modulated gut microbiota composition, increased species richness, and elevated levels of short-chain fatty acids such as acetic acid, propionic acid, and butyric acid. Enzyme-Linked Immunosorbent Assay (ELISA) results showed that XFZY reduced pro-inflammatory cytokines - interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), while immunohistochemistry indicated enhanced intestinal barrier function and reduced neuroinflammation. Furthermore, after depletion of gut microbiota using antibiotic cocktails, these therapeutic effects of XFZY were abolished. In summary, XFZY may alleviate PSD by modulating the gut microbiota and regulating the gut-brain axis, offering a promising direction for future therapeutic research.