Objective By means of animal study,investigated the gut barrier function in severe acute pancreatitis ( SAP),and role of inflammatory factors releasing,gut mucosa oxidative stress,cell apoptosis in it.Methods The animal experiment was done in the animal center of first people' s hospital,shanghai jiaotong university.Twenty four BALB/c mice were randomized ( random number) divided into two groups with twelve mice each group.The SAP group,mice received six intraperitoneal injections of cerulein at 1-hour intervals, the dose was 50μg/kg, then given one intraperitoneal injection of 10 mg/kg lipopolysaccharide ( LPS from E.Coli) for the induction of severe acute pancreatitis.The control ( sham operation) group,the mice received intraperitoneal injection of 2 ml normal saline for six times at 1-hour intervals.All the animals of each group were averaged to two batches,4 h and 8h after being operated respectively,to be anesthetized and adopted blood and tissue specimen.Then we observed the pathological change of pancreas and gut,scored it.We measured the blood value of diamine oxidase ( DAO),amylase and tumor necrosis factor-α (TNF-α).We detected content of malondialdehyde (MDA),superoxide dismutase (SOD),glutathione (GSH) and activity of xanthine oxidase (XO) in gut mucosa.We detected the casepase-3 activity and cell apopotosis by means of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) in gut mucosa,and conculated the apopotosis index (AI).Then using the PASW 18.0 software,we analyzed the data by anova and t-test,to make sure if the values were statistically different between the two groups and the mechanism of gut barrier dysfunction in panreatitis.Results At 4 h and 8 h after operation,the SAP-group-mice had significantly higher pancreas pathological score (P ＜0.01 ),blood amylase value ( P ＜ 0.05 ),gut pathological score and blood DAO and TNF-α value ( P ＜0.01 ),compared with the contral-group-mice.The gut mucosa MDA content and XO activity of mice in SAP group were significantly higher than which in control group ( P ＜ 0.01 ). The SAP-group-mice had significantly lower gut mucosa SOD content ( P ＜ 0.01 ) and GSH content ( P ＜ 0.05 ),compared with the contral-group-mice.The gut mucosa cells of mice in SAP group had significantly higher caspase-3 activity and apoptosis index than which in control group ( P ＜ 0.01 ).Conclusions In severe acute pancreatitis,inflammatory factors such as TNF-αwere waterfall-style released,induced gut mucosa suffer from ischemia-reperfusion injury,then serious oxidative stress developed in mucosa and activated caspase-3 pathway,inducing gut mucosa cells apoptose seriously,which was an important mechanism of gut barrier dysfunction.