Chaihu Shugan San alleviates depression-like behavior in rats exposed to chronic unpredictable mild stress by targeting α2δ-1-NR1 complex in hypothalamus

OBJECTIVE: Chaihu Shugan San (CSS) is a classical traditional Chinese medicine formula widely used in improving depression. The purpose of this study was to investigate the molecular mechanisms underlying the antidepressant effects of CSS. METHODS: Behavioral experiments and ELISA were employed to assess depressive-like behaviors and measure serum ACTH and CORT levels in chronic unpredictable mild stress (CUMS) rats. Western blotting, immunofluorescence, and Co-Immunoprecipitation were used to analyze α2δ-1 and NMDAR subunit NR1 expression and interactions in the hypothalamus. Cacna2d1 gene knockout and a disruptive peptide (α2δ-1 Tat) were applied in vitro to investigate the α2δ-1-NR1 complex. KEY FINDINGS: CSS ameliorated depressive-like behaviors in CUMS rats and decreased serum levels of ACTH and CORT. CSS reversed the upregulated expression of α2δ-1 and NR1 in the hypothalamus of CUMS rats, weakening the α2δ-1-NR1 complex binding. When the Cacna2d1 gene was knocked out or the α2δ-1-NR1 complex was disrupted with α2δ-1 Tat peptide, CSS-containing serum failed to significantly enhance NR1 expression in PC12 cells. CONCLUSION: CSS ameliorates depressive-like behaviors in CUMS rats by interfering with the α2δ-1-NR1 complex, reducing the expression levels of α2δ-1 and NR1 in the hypothalamus, and consequently inhibiting the excessive excitability of the hypothalamic-pituitary-adrenal axis.