Premila Abraham

ABSTRACT

Aim: Methotrexate (MTX) is a structural analogue of folic acid and is widely used in the treatment of leukaemia and other malignancies, rheumatoid arthritis and other rheumatic disorders. Gastrointestinal mucositis is a frequent dose-limiting side effect of methotrexate (MTX) chemotherapy. The underlying mechanisms of the mucositis is not completely understood. In the present study we examined the effect of MTX treatment on iNOS gene expression, protein tyrosine nitration protein cysteine nitrosylation, and the activities of mitochondrial enzymes in the small intestinal mucosa of rats Methods: Gastrointestinal injury was induced in the rats by the administration of 3 consecutive i.p. injections of 7 mg /kg body wt. MTX .The small intestines were used for light microscopy and immunohistochemical localisation of iNOS, nitrotyrosine (NTy) and nitrocysteine (NCy). Mucosal scrapings were used for iNOS mRNA expression by RTPCR, iNOS protein, nitrotyrosine and protein cysteine adducts formation by western blot and assay of key mitochondrial enzymes. Results: MTX treatment resulted in moderate to severe damage to the small intestines. iNOS mRNA expression , iNOS protein, NTy protein adduct and NCy adducts were increased in the MTX treated rat intestines.