To provide experimental basis and theoretical guidance for further research on the molecular mechanism of notoginsenoside R_1(NGR_1) in the treatment of depression, the present study analyzed the potential mechanism of NGR_1 in the treatment of depression through network pharmacology and verified it by molecular docking and animal experiments. PharmMapper, SwissTargetPrediction, and GeneCards were used to predict the related targets of both NGR_1 and depression to obtain the potential targets of NGR_1 in the treatment of depression. The database for annotation, visualization and integrated discovery(DAVID) was used for GO functional annotation and KEGG pathway enrichment analysis to screen the possible mechanisms of NGR_1 exerting antidepressant effect. Cytoscape 3.9.0 was adopted to construct a protein-protein interaction(PPI) network, and the topological analysis was performed to obtain the core targets. The binding activity of NGR_1 to core targets was tested by molecular docking. The depression model was prepared by injecting lipopolysaccharide(LPS) into the lateral ventricle in mice, and intervened with NGR_1. The antidepressant effect of NGR_1 was detected by behavioral tests and RT-qPCR. The results showed that by network pharmacology, 56 common targets of NGR_1 and depression were predicted, and GO enrichment analysis determined 13 related biological processes, mainly involving G protein-coupled receptor signaling pathway, positive regulation of transcription from RNA polymerase Ⅱ promoter, cytokine-mediated signaling pathway, gene expression, apoptosis, cell proliferation, and signal transduction. In addition, KEGG pathway enrichment analysis identified ten potential pathways, including neuroactive ligand-receptor interaction signaling pathway, lipid and atherosclerosis signaling pathway, cAMP signaling pathway, PI3 K-AKT signaling pathway, and lipid and atherosclerosis signaling pathway. PPI analysis revealed that the core targets included CASP3, VEGFA, IGF1, STAT3, MAPK1, PPARG, MTOR, MAPK14, NR3 C1 and AR, and molecular docking demonstrated that NGR_1 had desirable binding activity to these target proteins. In animal experiments, the results showed that NGR_1 improved the disease behavior of depressed mice, significantly inhibited the neuroinflammatory response(reducing the mRNA expression of Iba-1, TNF-α, IL-1β, and IL-6), and regulated the mRNA expression of lipid and atherosclerosis signaling pathway-related targets(CASP3, STAT3, MAPK1 and MAPK14). This indicated that the antidepressant mechanism of NGR_1 may be related to the regulation of lipid and atherosclerosis signaling pathway. In conclusion, network pharmacology was used to reveal the core targets and pathways of NGR_1, and some of them were verified in animal experiments, which provided the basis for in-depth exploration on the mechanism of NGR_1 in the treatment of depression.
Keywords: depression; molecular docking; network pharmacology; neuroinflammation; notoginsenoside R_1.