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 microg/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.

Infliximab: a new therapeutic agent in acute pancreatitis?

PURPOSE: Tumor necrosis factor alpha (TNF-alpha) has a central role in the pathogenesis of acute pancreatitis and related systemic complications. The aim of this study is to investigate the therapeutic effectiveness of monoclonal TNF antibody (infliximab) in acute edematous and severe necrotizing pancreatitis models in rats. METHODS: One hundred rats were randomly divided into 10 groups. Acute edematous pancreatitis (AEP) was induced by injection of cerulein 20 microg/kg 4 times subcutaneously at hourly intervals. Severe necrotizing pancreatitis (SNP) was induced by retrograde injection of 3% taurocholate into the common biliopancreatic duct. Infliximab 8 mg/kg was given via intravenous infusion. Serum amylase activity, pancreatic histopathology, myeloperoxidase enzyme activity (MPO), and pulmonary changes were assessed. RESULTS: Infliximab treatment significantly decreased serum amylase activity (11939 +/- 1914 U/L versus 3458 +/- 915 U/L, P < 0.001) and histopathologic score (4.1 +/- 0.5 versus 1.5 +/- 0.3, P < 0.001) in AEP. It also suppressed neutrophil infiltration and MPO activity of the pancreatic tissue. In SNP, infliximab treatment was found to decrease pathologic score (9.4 +/- 1.2 versus 3.6 +/- 0.8, P < 0.001) and serum amylase activity (20442 +/- 2375 versus 8990 +/- 1730, P < 0.01). It ameliorated both parenchymal and fatty tissue necrosis of the pancreas. Infliximab also alleviated alveolar edema and acute respiratory distress syndrome like pulmonary complications, but the difference was not significant. CONCLUSIONS: Chimeric TNF antibody, infliximab, should be evaluated for treatment of acute pancreatitis.

Effects of pentoxifylline on alcohol-induced gastric injury and acid secretion in rats.

We aimed to evaluate the protective effects of pentoxifylline on alcohol-induced gastric injury, its relation with nitric oxide and prostaglandin synthesis, as well as gastric acidity in rats. Acute gastric mucosal injury was induced by intragastric infusion of 2 ml 98% alcohol. Pentoxifylline was given at 100 mg/kg intraperitoneally. Indomethacin and N(G)-nitro-L arginine were used to inhibit prostaglandin and nitric oxide synthesis, respectively. Macroscopic and microscopic gastric injuries were evaluated. Gastric pH, tissue malondialdehyde levels, oxidized and reduced glutathion (GSSG/GSH) levels, and effects of pentoxifylline on gastric acid output were measured. Pentoxifylline pretreatment significantly reduced macroscopic and microscopic gastric injury. Malondialdehyde level was lower in pentoxifylline treated rats (351.1 +/- 94.1 nmol/g vs 624.3 +/- 234.2 nmol/g). Pentoxifylline has a protective role on alcohol-induced gastric mucosal injury in rats. This effect is not related to synthesis of prostaglandins and changes in gastric acidity but does seem to be related to nitric oxide-mediated pathways. In contrast, pentoxifylline increases gastric acid output significantly.

Effects of methimazole pretreatment on cerulein induced acute pancreatitis in rats.

BACKGROUND: Many interrelationships exist between the thyroid gland and the gastrointestinal tract. Several past and recent studies have shown that the thyroid gland profoundly influences the structure and function of the exocrine pancreas in the rat. In the present study we investigated the effect of methimazole (METZ), an antithyroid drug, on cerulein induced acute pancreatitis (AP) in rats. METHODS: Rats were divided into 3 groups (10-12 weeks age, 200-250 g weight, n: 10). Group B was made hypothyroid with methimazole 5 mg/kg daily for 10 days and the others were untreated euthyroid groups. After 10 days, acute pancreatitis was induced with four doses of 20 microg/kg body weight of cerulein administered s.c at hourly intervals in group A and B while the control group C was given 4 doses of I ml saline. Pancreas wet weight (mg), plasma amylase activity (IU/l) and pancreatic histology were used as endpoints to quantify the severity of the AP. RESULTS: Plasma tri-iodothyronine (T3) (ng/dl) and thyroxine (T4) (microg/dl) levels were significantly reduced after METZ treatment for 10 days (p < 0.01). METZ pretreatment reduced significantly the cerulein induced increase in pancreatic weight (1,205 +/- 12 mg in METZ treated AP group versus 1,617 +/- 14 mg in AP group, p < 0.05) and the rise in amylase activity (7,078 +/- 816 IU/l in METZ treated AP group versus 8,611 +/- 830 IU/l in AP group p < 0.05). CONCLUSION: METZ reduces the severity of cerulein induced AP in rats. This effect might be through its antithyroid property.

Effect of omeprazole on plasma zinc levels after oral zinc administration.

BACKGROUND: The intestines are the major site of zinc absorption and excretion. Reduced gastric acid secretion and elevated gastric pH is an important factor affecting intestinal mineral absorption. METHODS: Gastric pH and volume, and basal and maximal acid outputs were measured in 14 healthy volunteers. Plasma zinc levels were then measured at baseline and 1, 2, 3 and 4 hours after oral administration of 300 mg zinc sulfate. The experiment was repeated after omeprazole administration (60 mg/day orally) for 7 days. RESULTS: Omeprazole administration significantly increased fasting gastric pH (5.5 versus 2.4; p < 0.001). Mean basal gastric acid output (1.6 vs 8.0 mEq/h; p < 0.001) and maximal acid output (20.6 vs 106.6 mEq/h; p < 0.001) decreased after omeprazole administration. Zinc absorption decreased after omeprazole administration (141 [34] mg/dL/h) compared with pre-omeprazole values (245 [35]; p < 0.01). CONCLUSION: Suppression of gastric acid secretion by omeprazole reduces intestinal absorption of zinc.