RESUMEN
Acute pancreatitis [AP] is a complex disease associated with significant complications and a high rate of mortality. The aim of this work was to study the effect of the antioxidant melatonin on cerulein-induced pancreatitis in adult male albino rats. Thirty two adult male albino rats were used and randomly divided into four groups: first group [control]; second group [melatonin treated]; third group [cerulein treated] and fourth group [melatonin and cerulein treated group]. At sacrifice, blood samples were drawn for biochemical study and pancreas specimens were prepared for histological, and histochemical study. Melatonin reduced serum amylase and lipase activities, which were highly significantly elevated in cerulein induced pancreatitis. Histologically there was wide separation between pancreatic lobules, the acinar cells showed degeneration and vacuolation and lost their zymogen granules. There was dilatation and congestion of blood vessels, interstitial hemorrhage and cellular infiltration. Ultrastructurally, there was disorganized dilated rough endoplasmic reticulum [RER], marked decrease in zymogen granules, mitochondrial damage and cytoplasmic vacuoles. Immunohistochemically, pancreatic sections of cerulein treated rats showed a strong immune reaction for transforming growth factor-beta [TGF-beta] and vascular endothelial growth factor [VEGF]. Melatonin improved the biochemical, histological, and histochemical picture of pancreas. In conclusion, melatonin was found to be effective in cerulein-induced acute pancreatitis by preventing oxidative stress so prevents other pathological mechanisms of AP from being developed inside acinar cells