Chemical Characteristics and Antidepressant Mechanism of Fresh and Stir-fried Ziziphi Spinosae Semen in Chronic Unpredictable Mild Stress Rats: Effects on Neurotransmitters, Inflammation and Gut Microbiota

Abstract This study utilized 60 rats subjected to chronic unpredictable mild stress (CUMS) for 21 days to investigate the chemical profiles, pharmacodynamic characteristics, and antidepressant effects of raw Ziziphi Spinosae Semen (ZSS) and stir-fried Ziziphi Spinosae Semen (FZSS). Behavioural assessments revealed that both ZSS and FZSS alleviated depression-like behaviours in CUMS rats, as evidenced by increased exploratory activity in the open field test, reduced immobility time in the forced swim test, and elevated sucrose preference (all P 0.01). ELISA results demonstrated that both treatments regulated HPA axis hormone levels, decreased pro-inflammatory cytokine concentrations, and restored neurotransmitter balance in the brain. Additionally, they upregulated the BDNF–TrkB-CREB signalling pathway and enhanced ERK1/2 phosphorylation in the hippocampus, with FZSS and a 1:1 mixture of raw and stir-fried ZSS exhibiting more pronounced effects. Furthermore, GC–MS was employed to SCFAs, and 16S rRNA gene sequencing was conducted to analyse gut microbiota diversity. These findings suggest that the frying process may enhance the antidepressant efficacy of ZSS, potentially through the enrichment of bioactive components present in the raw material, as well as the modulation of neurotransmitter homeostasis, anti-inflammatory responses, neurotrophic signalling pathways, and gut microbiota metabolic functions.