Study on the antidepressive effects and mechanism of raw and fried Ziziphi Spinosae Semen via metabolomics and gut microbiota analysis

Ziziphi Spinosae Semen (ZSS) and fried ZSS (FZSS) have been used for treating insomnia and depression in China. However, the potential influence of chemical variations on their efficacy remains unclear. This study demonstrated that compared with ZSS, FZSS exhibited an increase in the content of seven compounds, while the fatty oil content decreased. Both ZSS and FZSS exhibited antidepressive effects in a chronic unpredictable mild stress rat model, indicating a synergistic regulation of deficiencies in 5-hydroxytryptamine in the brain and the hyperactivation of severe peripheral inflammation. ZSS demonstrated a superior modulatory effect compared with FZSS, as indicated by integrated pharmacodynamic index, metabolic profile, and relative distance value. The potential mechanism underlying their antidepressive effects involved the modulation of gut microbiota structure to alleviate excessive inflammatory responses and imbalanced tryptophan metabolism. Correlation analysis indicated that the higher fatty oil contents should be comprehensively considered as the main reason for ZSS's superior antidepressive effects, achieved through the regulation of pyroglutamic acid levels.