The effect of antioxidant therapy on colonic inflammation in the rat

Under normal physiological conditions, chemical and antioxidant defenses pr otect tissues from the damaging effects of reactive oxygen metabolites (ROM ). It has been proposed that ROMs are involved in the development of tissue injury in many inflammatory diseases and also in patients with colitis. In the present study we aimed to investigate the effects of antioxidant thera py on the extent of colonic inflammation and ROM levels in the injured tiss ues in a trinitrobenzene sulfonic acid-induced colitis model in the rat. Sp rague-Dawley rats were pretreated with the antioxidants superoxide dismutas e (30,000 U/kg s.c.) or catalase (400,000 U/kg s.c.) prior to induction of colitis and they were decapitated 24 h (acute group) or 6 days (chronic gro up) after the induction of colitis (each group consists of eight to ten rat s). Pretreatment with the antioxidants reduced the macroscopic damage score significantly in both acute and chronic groups compared with untreated col itis groups, whereas they reduced the microscopic damage score and colonic wet weight only in the chronic group. The chemiluminescence assay - a techn ique to assess the presence of reactive oxygen species in the tissues - val ues of the groups pretreated with the antioxidants showed a tendency to dec rease compared with the untreated colitis group, but they were not statisti cally significant. Based on these findings, pretreatment with the antioxida nts superoxide dismutase or catalase has beneficial effects on the extent o f colonic inflammation, particularly in the chronic period, and this may su pport the importance of antioxidant therapy to reduce the severity of infla mmatory bowel disease in humans.