Objective The study was designed to investigate the intestinal mucosa barrier function changes in rats with severe acute pancreatitis (SAP),and the intervention effect of epigallocatechin-3-gallate(EGCG) injection and its mechanisms of protection on intestinal mucosa barrier function injury of SAP with the purpose of providing evidence for preventing and curing intestinal mucosa barrier function injury of SAP in clinical practice.Methods A total of 80 healthy male Sprauge-Dawley (SD) rats were randomly divided into a normal group (Normal),a sham-operation group (Sham),a SAP model group (Model),and a EGCG treated group (EGCG),with 24 rats (except 8 rats in the normal group) in each group.The latter three groups each had three subgroups at three time points:6,12,24hours.Rats with SAP were prepared with retrograde cholangiopancreatic duct infusion in 5％ sodium taurocholate.The dynamic changes of the indexes of intestinal mucosa barrier function injury and Pancreas injury were observed at various time points in each group,including the levels of Plasma diamine oxidase (DAO) and serum amylase and malondialdehyde (MDA),nitric oxide(NO),inducible nitric oxide synthase(iNOS)in gut.Results 1.The levels of serum amylase [(3158.64 ± 218.25)μ/L,(4277.24 ± 231.35)μ/L,(5842.76 ± 248.18)μ/L] and plasma DAO concentration [(4.23 ± 0.51) μ/L,(5.13 ± 0.32)μ/L,(7.83 ± 0.76) μ/L] in the Model group were significantly higher at 6 h,12 h,24 h postoperation than the Normal group[serum amylase:(2074.11 ± 101.56)μ/L,DAO:(2.32 ± 0.48) μ/L] and Sham group [serum amylase:(1885.27 ± 103.89) μ/L,(1778.57 ± 98.94) μ/L,(1935.24 ± 105.87) μ/L].The levels of serum amylase [(2576.70 ± 123.43) μ/L,(2783.77 ± 155.53) μ/L,(2902.32 ±176.25) μ/L] and plasma DAO concentration (3.59 ± 0.57) μ/L,(3.98 ± 0.67) μ/L,(6.44 ± 0.71) μ/L in the EGCG group were lower than the Model group,but higher than the Normal group and the Sham group.Compared with the Normal group and the Sham group,the concentration of MDA and NO [MDA:(2.28±0.35) μmol/g,(3.02 ± 0.41) μmol/g,(3.78 ± 0.48) μmol/g ; NO:(16.80 ± 0.60) μmol/g,(18.23 ± 0.78) μmol/g,(20.14±0.82) μ,mol/g] significantly increased in the Model group at 6h,12 h,and 24 h postoperation.The concentration of MDA and NO (1.67±0.14) μmol/g,(1.75±0.16) μmol/g,(1.84±0.22) μmol/g; NO:(9.09±0.31) μmol/g,(9.32±0.44)μmol/g,(10.15±0.52)μmol/g were lower in the EGCG group in all times than the Model group.Compared with the Normal group (0.10) and the Sham group (0.25).The expression ofiNOS was significantly increased in the Model group(1.86).The expression of iNOS was lower in the EGCG group (0.66) in all times than the Model group,but higher than the Normal group and the sham group (P＜0.05).Conclusion Conclusion EGCG can protect the damages of intestinal mucosa barrier function in SAP rats,probably through reducing free radicals,and the iNOS expression.