The therapeutic potential of Ziziphi Spinosae Semen and Polygalae Radix in insomnia management: Insights from gut microbiota and serum metabolomics techniques

Ethnopharmacological relevance: Ziziphi Spinosae Semen and Polygalae Radix (ZSS-PR) constitute a traditional Chinese herbal combination with notable applications in clinical and experimental settings due to their evident sedative and calming effects. Aligned with traditional Chinese medicine principles, Ziziphi Spinosae Semen supports cardiovascular health, nourishes the liver, and induces mental tranquillity. Simultaneously, Polygalae Radix elicits calming effects, fosters clear thinking, and reinstates proper coordination between the heart and kidneys. ZSS-PR is commonly employed as a therapeutic intervention for various insomnia types, demonstrating distinct clinical efficacy. Our previous study findings provide evidence that ZSS-PR administration significantly reduces sleep onset latency, increases overall sleep duration, and improves abnormal neurotransmitter levels in a murine insomnia model. Aim of study: This investigation aimed to scrutinize the intrinsic regulatory mechanism of ZSS-PR in managing insomnia using gut microbiota and serum metabolomics techniques. Materials and methods: Mice were given DL-4-Chlorophenylalanine to induce insomnia and then treated with ZSSPR. The open-field test assessed the animals' spontaneous activity. Concentrations of neurotransmitters, endocrine hormones, and cytokines in the duodenum were measured using enzyme linked immunosorbent assay, and brain histopathology was evaluated with H&E staining. The impact of ZSS-PR on the metabolic profile was examined by liquid chromatography couped to high resolution mass spectrometry, and 16S rDNA sequencing was used to study the influence of ZSS-PR on the gut microbiota. Additionally, the content of short-chain fatty acids (SCFAs) was analyzed by GC-MS. Finally, correlation analysis investigated relationships between biochemical markers, metabolites, SCFAs, and gut microbiota. Results: ZSS-PR treatment significantly increased movement time and distance in mice with insomnia and improved pathological impairments in the cerebral cortex and hippocampus. It also restored abnormal levels of biochemical markers in the gut of insomnia-afflicted mice, including 5-hydroxytryptamine, dopamine, gastrin, melatonin, tumour necrosis factor-alpha, and interleukin-1 beta. Metabolomics findings showed that ZSS-PR had a significant restorative effect on 15 endogenous metabolites in mice with insomnia. Furthermore, ZSS-PR primarily influenced five metabolic pathways, such as phenylalanine, tyrosine, and tryptophan biosynthesis, glutamine, and glutamate metabolism. Additionally, gut microbiota analysis revealed notable alterations in both diversity and microbial composition after ZSS-PR treatment. These changes were primarily attributed to the relative abundances of microbiota, including Firmicutes, Bacteroidota, Fusobacteriota, Muribaculaceae_unclassified, and Ligilactobacillus. The results of SCFAs analysis demonstrated that ZSS-PR effectively restored abnormal levels of acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, and valeric acid in insomniac mice. Subsequent correlation analysis revealed that microbiota show obvious correlations with both biochemical markers and metabolites.