Study On The Mechanism Of Forsythiae Fructus In The Prevention And Treatment Of Chemotherapy-induced Nausea And Vomiting Based On NLRP3 Inflammasome

IVObjective:To explore the effect and mechanism of Forsythiae Fructus in preventing and treating chemotherapy-induced nausea and vomiting(CINV)based on the NLRP3 inflammasome.Methods:1.Preparing lyophilized powder of Forsythiae Fructus,and the content of forsythin and forsythiaside A in Forsythiae Fructus and lyophilized powder of Forsythiae Fructus were determined by high performance liquid chromatography(HPLC).2.Wistar male rats were randomly divided into five groups: blank control group,Forsythiae Fructus normal control group,cisplatin model group,positive drug treatment group and Forsythiae Fructus treatment group.These group were given(intragastric administration,i.g.)distilled water,Forsythiae Fructus(1.75 g crude drug/kg),distilled wate,dexamethasone(0.47 mg/kg),Forsythiae Fructus(1.75 g crude drug/kg)respectively every12 h(at 8:00 AM and 8:00 PM)for 6 consecutive days.At 9:00 AM on day3(after i.g.),rats were injected intraperitoneally(i.p.)with 6 mg/kg cisplatin to establish the rat pica models except the blank control group and the normal control group of Forsythiae Fructus.The general condition of rats was observed every 24 hours,and the consumption of kaolin(as an index of nausea and vomiting),food intake and body weight of rats in each group were measured every day at 7:00 AM.The histopathological changes of gastric antrum and ileum were observed by HE staining,the contents of reactive oxygen species(ROS),interleukin-1β(IL-1β)and interleukin-18(IL-18)in serum were determined by enzyme linked immunosorbent assay(ELISA),the protein expression levels of NLRP3,ASC,caspase-1 and IL-1β in gastric antrum and ileum,and the co-localization of the NLRP3 with ASC or caspase-1 were detected by western blot and immunofluorescence respectively.Results:1.The contents of forsythin and forsythiaside A in Forsythiae Fructus was0.21% and 2.70% respectively,which in lyophilized powder of Forsythiae Fructus was 0.28% and 2.62% respectively.2.The consumption of kaolin in the cisplatin model group were significantly increased compared with the blank control group,indicating that the rat pica models were successfully constructed.Inflammatory pathological changes were observed in gastrointestinal mucosa in cisplatin model group.The levels of ROS,IL-1β and IL-18 in serum were significantly increased of model group(P<0.05,P<0.01).The protein expression levels of NLRP3,ASC,caspase-1 and IL-1β in gastric antrum and ileum were significantly increased(P<0.05,P < 0.01,P < 0.001),and the co-localization of the NLRP3 with ASC or caspase-1 were enhanced(P<0.05).Compared with the model group,Forsythiae Fructus significantly reduced the kaolin intake and ameliorated the gastrointestinal histopathological injury in rats treated with cisplatin,it significantly decreased the serum levels of ROS,IL-1β and IL-18,downregulated protein expression of NLRP3,ASC,caspase-1 and IL-1βin the rat gastric antrum and ileal tissue,and strongly weakened the colocalization of NLRP3 with ASC or caspase-1 in gastrointestinal tissue of the model group(P<0.05,P<0.01).Conclusion:Forsythiae Fructus can significantly inhibit rat pica behavior induced by cisplatin,suggesting that it has a preventive and therapeutic effect on CINV,and its mechanism may be related to the inhibition of the activation of NLRP3 inflammasome.