The Protective Effects Of Saponins From Platycodi Radix On Cisplatin-induced Intestinal Injury Via Endoplasmic Reticulum Stress Pathway

There are abundant triterpene saponins(Platycodon grandiflorum saponins,PGS)in Platycodon grandiflorum,which are isolated and found in Platycodon grandiflorum.This research group has proved that PGS has abundant pharmacological activities,especially its ability to antagonize the kidney damage caused by Cisplatin(CP).Studies have found that the side effects of CP mainly include nephrotoxicity,liver toxicity,gastrointestinal toxicity,ototoxicity,cardiotoxicity,and neurotoxicity.However,the protective effect of PGS on intestinal injury caused by CP is currently unknown.This study is based on the PERK-e IF2ɑ-ATF4 Endoplasmic Reticulum stress signaling pathway to establish CP-induced intestinal injury in vivo model and CP-induced rat small intestinal crypt epithelial cell line IEC-6 intestinal injury model.Two parts of the content are in-depth analysis of PGS.The protective effect of PD and PD on the intestinal tract,and reveal its potential molecular mechanism,mainly conducted three aspects of research work:1.Protective effect of PGS on intestinal injury induced by CP.(Animal experiment)CP-induced acute intestinal injury model in mice was established,and its protective effect was observed by pre-administering PGS.The experimental results showed that72 h after a single injection of CP,the small intestinal villi of the model group shrank,shedding,density and height decreased,diamine oxidase(DAO),malondialdehyde(MDA)levels increased sharply,and superoxide dismutation Enzyme(SOD)depletion,intestinal tight junction protein(ZO-1)and(Occludin)expression decreased.The intragastric administration of PGS at 15 and 30 mg/kg for 10 consecutive days significantly improved these symptoms.DAO and MDA levels were reduced,SOD activity was restored,and the expression of ZO-1 and Occludin in the small intestine of mice increased.Further mechanism studies have found that CP attacks the body’s oxidative system to cause a large accumulation of unfolded or misfolded proteins in the endoplasmic reticulum,activates the endoplasmic reticulum stress receptor PERK,and causes Endoplasmic Reticulum stress and cell apoptosis.Overall,our research shows that PGS inhibits oxidative stress and apoptosis by inhibiting the endoplasmic reticulum stress pathway,and strengthens the intestinal mechanical barrier,thereby exerting an intestinal protective effect.2.PD relieves CP-induced intestinal injury in mice by regulating the PERK-e IF2ɑ-ATF4 endoplasmic reticulum stress signaling pathway.(Animal experiment)PD is a representative saponin component in PGS.By analyzing the results of PGS on CP-induced intestinal injury,the intestinal injury model of PD was established to explore the in vivo molecular mechanism and protective effect of PD on CP-induced intestinal injury.The results showed that the decrease of serum tumor necrosis factor(TNF-ɑ)and the decrease of myeloperoxidase(MPO)expression in the duodenum showed that PD(2.5 mg/kg and 5 mg/kg)can partially inhibit CP Induced intestinal inflammation in mice.In addition,the increase of MDA level in mice and the decrease of SOD activity indicate the body’s redox imbalance,which may induce Endoplasmic Reticulum stress response.Western Blot results showed that PD significantly inhibited the expression of Endoplasmic Reticulum stress-related protein PERK,eukaryotic initiation factor 2α(e IF2ɑ)phosphorylation,activating transcription factor-4(ATF4),and C/EBP homologous protein(CHOP)reduce.Inflammation and oxidative stress in mice may induce endoplasmic reticulum stress.In this paper,by analyzing the expression of PERK-e IF2ɑ-ATF4 signaling pathway protein,the protective mechanism of PD on CP-induced intestinal injury in mice was deeply explored.3.The protective effect of PD on IEC-6 cell injury induced by CP.(Cell experiment)In this paper,we established an in vitro model of CP-induced IEC-6 cell intestinal injury to further prove the protective effect of PD on CP-induced intestinal injury,and explore the protective mechanism of PD on CP-induced IEC-6 cell Endoplasmic Reticulum stress.Analysis of MTT results showed that PD at doses of 2μM,4μM,and8μM could restore the cell viability of IEC-6 cells in a dose-dependent manner.PD can partially inhibit the excessive production of ROS caused by CP,reduce MDA levels,restore SOD activity,and show the antioxidant activity of PD.Flow cytometry and Western Blot results further clarify that PD inhibits CP-induced apoptosis of IEC-6 cells by reducing cytochrome,cl-caspase 9,cl-caspase 3,and increasing Bcl-2protein expression.In addition,the phosphorylation of PERK and e IF2ɑ,as well as the expression of ATF4 and CHOP after PD pretreatment,showed a significant reduction trend,suggesting that PD may protect the CP-induced intestine by regulating the PERK-e IF2ɑ-ATF4 pathway inhibiting the Endoplasmic Reticulum stress.and cell damage.In summary,the protective effect of PD on CP-induced IEC-6cell damage may be related to the reduction of the unfolded protein response caused by oxidative stress,the inhibition of Endoplasmic Reticulum stress,and the inhibition of intestinal cell apoptosis.In summary,the results of this study reveal that PD can improve CP-induced intestinal injury by reducing oxidative stress,inflammation,endoplasmic reticulum stress,apoptosis,and intestinal mechanical barrier damage caused by CP,which may and regulate the Endoplasmic Reticulum stress-mediated PERK-e IF2ɑ-ATF4 signaling pathway and its mediation of apoptosis are related.Therefore,PGS and PD may provide a theoretical basis for the development of clinically coordinated drugs to relieve gastrointestinal reactions caused by chemotherapy drugs in the future.