Effects of melatonin on the oxidative damage and pancreatic antioxidant defenses in cerulein-induced acute pancreatitis in rats

BACKGROUND: Oxidative stress is recognized as a pivotal effector of several pathogenic processes, including acute pancreatitis. Reactive oxygen species not just cause damage on the main cellular components, but also influence the expression of antioxidant system genes. Antioxidant molecules, such as melatonin, could be good candidates for the treatment of this multidimensional disease. The present study was to evaluate the chemopreventive effect of melatonin in a rat model of cerukin-induced acute pancreatitis. METHODS: Four subcutaneous injections of cerukin (20 mu g/kg body weight) were given to Wistar rats at two hours intervals; melatonin was injected intraperitoneally (25 mg/kg body weight) 30 minutes before each injection of cerulein. Lipid peroxidation, protein oxidation (carbonyl groups), total antioxidant status, and glutathione peroxidase activity were determined in pancreatic tissue using commercial kits. RESULTS: The chemopreventive administration of melatonin caused a reduction in lipid peroxidation and protein oxidation due to injections of cerulein. Additionally, melatonin treatment was also able to revert glutathione peroxidase activity and total antioxidant status near to control levels, suggesting that melatonin could prevent from oxidative phenomena in the pancreas, such as lipid peroxidation and protein oxidation, and could stimulate, directly or indirectly, the expression of antioxidant enzymes. CONCLUSION: Melatonin, a polyvalent antioxidant, protected the pancreatic damage via the decrease of oxidative stress and increase of the activities of antioxidant enzymes in cerulein-induced acute pancreatitis.