Leukotriene receptor antagonism in experimental acute pancreatitis in rats

Objectives Acute pancreatitis is a multifactorial disease caused by activation of several inflammatory mediators. Leukotrienes, beside other mediators, may be involved in acute pancreatitis. The aim of this study was to investigate the effects of 'zafirlukast', a leukotriene receptor antagonist, in acute pancreatitis and its relation with prostaglandin synthesis. Methods Eighty rats were randomly divided into eight groups. Acute pancreatitis was induced by subcutaneous injection of cerulein (20 mug/kg), four times at 1-h intervals. Zafirlukast (20 mg/kg) was applied intraperitoneally as a pretreatment. Prostaglandin synthesis was inhibited by low-dose indomethacin (5 mg/kg subcutaneously). Pancreatic histopathology, serum amylase activity and pancreatic myeloperoxidase activity were determined to assess the severity of pancreatitis. Results Zafirlukast pretreatment alone did not induce any inflammation and fatty necrosis in pancreatic tissue. However, it increased the histopathological score from 3.70 +/- 0.57 to 6.62 +/- 0.53 in rats with acute pancreatitis (P < 0.001). Fatty necrosis was especially prominent in the zafirlukast-treated acute pancreatitis group compared with the untreated group (2.62 +/- 0.26 versus 0.40 +/- 0.22, respectively; P< 0.001). Inhibition of prostaglandin synthesis by indomethacin partially suppressed the harmful effects of zafirlukast in acute pancreatitis. It decreased the pathological score (4.62 +/- 0.73) and fatty necrosis (1.50 +/- 0.32) in that group. Conclusion Interestingly, leukotriene receptor antagonism by zafirlukast increased the pancreatic histopathological score and fatty necrosis in rats with acute pancreatitis. Blocking of cysteinyl leukotriene receptors might cause an induction of mediator synthesis; via other pathways. Effects of leukotriene receptor antagonism on the pancreas must be evaluated extensively in further studies.