Integrating hippocampal metabolomics and network pharmacology deciphers the antidepressant mechanisms of Xiaoyaosan

Xiaoyaosan (XYS), a classic description, has a history of thousands of years for treating depression through invigorating the liver and strengthening the spleen, which have been verified both clinically and experimentally. However, explanation of its underlying mechanisms remains a great challenge. The mechanisms of XYS in treating depression were investigated, with emphasis on the important biomarkers, targets and pathways. In this study, taking the targeted organ of depression, hippocampus, as the object, a combination of GC-MS based metabolomics and network pharmacology was established to illustrate the abnormality of metabolic characteristics of hippocampus of depression rats and to demonstrate the antidepressant mechanisms of XYS. Hippocampal metabolomics demonstrated potential metabolites involving in the antidepressant effects of XYS, as well as the corresponding metabolic pathways. Network pharmacology screened the potential ingredients and the targets of XYS against depression. Metabolomics revealed that XYS significantly regulated the abnormal levels of lactic acid, glycerol, glutamine, glutamic acid, hypoxanthine, myo-inositol and cholesterol, which involved in the D-glutamine and D-glutamate metabolism, arginine biosynthesis and alanine, aspartate and glutamate metabolism. Network pharmacology showed that XYS exhibited anti-depression effects through paeoniflorin, quercetin, licochalcone a, naringenin, β-sitosterol, formononetin and kaempferol acting on interleukin-6 (IL6), mitogen-activated protein kinase 1 (MAPK1), signal transducer and activator of transcription 3 (STAT3) and transcription factor AP-1 (JUN). Based on hippocampal metabolomics and network pharmacology, this study proved that the actions of XYS in treating depression depend on multi-components, multi-targets and multi-pathways, the unique characteristics of TCMs.