INDUCTION AND IMMUNOLOCALIZATION OF MANGANESE SUPEROXIDE-DISMUTASE INACUTE ACETIC ACID-INDUCED COLITIS IN THE RAT

Background and Aims: Oxygen radicals and reactive oxygen species play an important role in inflammatory episodes in the bowel. Nonetheless, little is known about the regulation of colonic superoxide dismutases and key antioxidant enzymes with cytoprotective and radical detoxifyin g properties. The aim of this study was to examine the regulation of m anganese superoxide dismutase (SOD) in acute acetic acid-induced colit is. Methods: Colitis was induced in adult rats by the rectal administr ation of 5% acetic acid. Total RNA and protein were isolated from the inflamed colon from 1 to 24 hours after the induction of colitis. MnSO D messenger RNA and protein levels were evaluated by Northern and West ern analyses, respectively. MnSOD protein was localized in cross secti ons of the colon by immunocytochemistry. Results: MnSOD messenger RNA levels showed a rapid 14-96-fold induction in response to acetic acid administration. Western analysis showed a 22-49-fold induction in MnSO D protein levels. Immunocytochemistry showed induction of MnSOD protei n, specifically in smooth muscle cells, epithelial cells at the base o f the glands, and myenteric plexus neurons. Conclusions: MnSOD messeng er RNA and protein levels are rapidly induced following the inflammato ry insult, implicating a role for MnSOD in the acute phase of colonic inflammation. We suggest that induction of MnSOD in specific cell type s may have a cytoprotective function.