Network pharmacology strategy to investigate the pharmacological effects of Suanzaoren Decoction on insomnia

Abstract Suanzaoren Decoction (SZRD) is an ancient prescription used in the treatment of insomnia. This study aimed to investigate the components and targets of SZRD in treating insomnia. First, the compounds of five herbs in SZRD were collected from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), and the putative targets for treating insomnia were obtained from DrugBank to construct the herb-compound-target- disease network. A protein-protein interaction (PPI) network was constructed in the STRING database, and then Gene Ontology functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed to predict the mechanism of action of intersection target. Finally, 30 mice were divided into five groups: control, model, and quercetin groups (100, 50, 25 mg/kg). The sleep latency and duration of pentobarbital-induced sleeping were measured. The production of interleukin-6 (IL-6) and γ-aminobutyric acid (γ-GABA) was detected by using an enzyme-linked immunosorbent assay kit (ELISA), and Gamma-aminobutyric acid type a receptor subunit alpha1 (GABRA1) was tested by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). A total of 152 active ingredients, including 80 putative targets of SZRD, were obtained. The main active compounds included quercetin and kaempferol, and the key targets involved IL-6 and nitric oxide synthase 3 (NOS3). The results of pathway enrichment analysis indicated that the putative targets of SZRD mainly participated in Neuroactive ligand-receptor interaction. The experiment of P-chlorophenylalanine (PCPA)-induced insomnia model showed that quercetin obviously shortened the sleep latency and prolonged the sleep duration of the insomnia model. The production of IL-6, γ-GABA, and GABRA1 mRNA was significantly increased in mice treated with quercetin. This study predicted the active ingredients and potential targets of SZRD on insomnia on the basis of a systematic network pharmacology approach and illustrated that SZRD might exert hypnotic effects via regulating IL-6, γ-GABA, and GABRA1

Effect of quercetin and role of nitric oxide pathway in chloroquine-induced scratching

Abstract Nitric oxide (NO) is an abundant mediator which is demonstrated to be involved in pruritus. Assuming that the increased NO also mediates chloroquine-induced pruritus, which is a frequent complication seen in the chronic chloroquine treatment, the current study aimed to investigate the effect of quercetin and the role of NO in chloroquine-induced pruritus in C57BL/6 mice. Model was created with subcutaneous chloroquine (400µg/site) injection to the nape of the mice. Effect of quercetin and role of NO were investigated with administration of quercetin, and co-administration with L-NAME, 7-NI and L-arginine before chloroquine injection. Locomotor activity was assessed by activity cage and number of the scratching bouts after chloroquine injection was recorded for 30 minutes. Our results show that quercetin significantly reduced scratching bouts at the doses of 10, 20, 40 and 80 mg/kg. Locomotor activity was decreased at the 40 and 80 mg/kg doses of quercetin. Additionally, decrease of the number of scratching bouts by quercetin prevented by L-arginine treatment, while L-NAME and 7-NI enhanced the anti-pruritic effect of sub-effective doses of quercetin. Therefore, our study demonstrated that acute injection of quercetin significantly diminished chloroquine-induced scratching behavior, and this effect is partly mediated by inhibition of neuronal nitric oxide synthase enzyme.