OBJECTIVETo observe the changes in intestinal mucosal permeability in rats with methotrexate (MTX)-induced small intestinal damage and investigate the protective effects of curcumin.

METHODSThe experiment was carried out using 4 groups of rats, namely the normal control group, enteritis model group, sulfasalazine (SASP) group and curcumin group. With the exception of the rats in the normal control group, all rats were subjected to intraperitoneal MTX injection to induce enteritis and received subsequent daily intragastric administration of SASP (100 mg/kg), curcumin (100 mg/kg), or normal saline for 5 days. The disease activity index (DAI), colonic mucosal damage index (CMDI) and histological score (HS) of the rats were evaluated. The levels of diamine oxidase (DAO) and D-lactate were assessed using spectrophotometric assay, and myeloperoxidase (MPO) activity and intracellular adhesion molecule-1 (ICAM-1) protein expression were measured by biochemical and immunohistochemical methods, respectively.

RESULTSCompared with the normal control group, the rats in the model group showed significantly increased DAI, CMDI and HS and levels of DAO, D-lactate, ICAM-1 and MPO. Curcumin treatment resulted in significantly decreased DAI, CMDI, HS and lowered activities of D-lactate, ICAM-1 and MPO in comparison with the model group (P<0.01).

CONCLUSIONMTX induces increased mucosal permeability of the small intestines in rats, and curcumin may offer protective effects against MTX-induced rat enteritis by lowering the intestinal mucosal permeability.