NF-κB-iNOS-COX2-TNF α inflammatory signaling pathway plays an important role in methotrexate induced small intestinal injury in rats.

Although methotrexate is widely used in clinics as an anticancer agent, it's utility is limited by its gastrointestinal toxicity, the mechanism of which is unclear. The role of NFκB inflammatory pathway in MTX induced mucositis was investigated in the present study. GI injury was induced in adult Wistar rats by the administration of 3 consecutive i.p . injections of MTX. On the fourth day, the rats were sacrificed and the small intestine was removed; A piece was used for light microscopy, immunohistochemistry, immunofluorescence studies . The mucosa was collected and used for the analysis of protein and mRNA expressions of NFκB and its target genes by the western blot, RT-PCR respectively. MTX treatment resulted in NFκB activation and nuclear translocation as evidenced by immunofluorescence, immunohistochemistry , and western blot. NFκB mRNA was also increased. There was increased protein and mRNA expressions of NFκB target genes, TNF-α, iNOS, COX-2, PLA2, HO-1, HSP70, MMPs 2 and 9 . Aminoguanidine pretreatment (30mg/ 50mg /kg body wt.) attenuated MTX induced activation of NFκB and its proinflammatory target genes and improved MTX induced morphological changes. Aminoguanidine has protective effects against MTX induced gastrointestinal mucositis in rats.