Abstract: Objective To explore the effect of 5-aminosalicylic acid (5-ASA)combined with antrum mucosal protein-18 (AMP-18)on the expression of myeloperoxidase (MPO),nuclear factor-kB(NF-kB)and epidermal growth factor (EGF)in trinitrobenzene sulphonic acid (TNBS)in-duced colitis rats.Methods 40 male sprague-dawley (SD)rats were randomly divided into group A,B,C and D.After the production of colitis,10 rats in each group were given the following topical treatments respectively:group A,normal saline;group B,5-ASA at the dose of 100 mg/kg;group C,AMP-18 at the dose of 10 mg/kg;group D,5-ASA and AMP-18.Animals were sacrificed at the 4th and 8th day after topical treatment.The macroscopic and histological changes of the colon were e-valuated and scored.MPO activity of the mucosa was detected by biochemical methods.Expressions of serum EGF and tissue NF-kB were detected by ELISA and immunohistochemistry respectively.Re-sults Compared with group A,macroscopic and histological scores and MPO activity in group B,C and D significantly decreased (P <0.05 ).Expressions of serum EGF were significantly higher in group B,C and D than in group A (P <0.01),while the expressions of tissue NF-kB significantly decreased (P <0 .0 5 ).The combination ofAMP -1 8 with 5 -ASA showed a better effect than single use of AMP -1 8 or 5 -ASA .Conclusion Topical treatment with 5 -ASA and AMP -1 8 shows a positive effect in treating TNBS-induced colitis rats,and combined treatment is better than single treatment.The mechanism is related to decreasing of content of colonic MPO,down-regulation of NF-kB and up-expression of EGF.