leukotriene-b4 and Pancreatitis

We tested the hypothesis that leukotriene B4 (LTB4) mediates pancreatic inflammation in rats via activation of the transient receptor potential vanilloid 1 (TRPV1).. Leukotriene B4 or a vehicle was administered to adult rats via celiac axis injection after pretreatment with the TRPV1 antagonist, capsazepine, or vehicle, and the severity of subsequent pancreatitis was assessed by measuring pancreatic edema, myeloperoxidase (MPO) activity, and histological grading. In a second experiment, acute pancreatitis was induced by common pancreaticobiliary duct ligation. Six hours after surgery, pancreatic tissue levels of LTB4 were determined by enzyme-linked immunosorbent assay. Also, the effects of inhibition of LTB4 biosynthesis by pretreatment with the 5-lipoxygenase-activating peptide inhibitor, MK-886, were determined.. Celiac axis administration of LTB4 significantly increased pancreatic edema and MPO activity, and produced histological evidence of pancreatic edema, neutrophil infiltration, and necrosis. Capsazepine pretreatment significantly reduced all inflammatory parameters in LTB4-induced pancreatitis. Pancreatic tissue levels of LTB4 were significantly elevated in rats that underwent common pancreaticobiliary duct ligation compared with control rats. MK-886 pretreatment significantly inhibited pancreatic edema, histological damage, and pancreatic MPO concentrations.. Common pancreaticobiliary duct obstruction causes an increase in pancreatic LTB4 concentrations that in turn mediates activation of TRPV1 resulting in acute pancreatitis.

Topics: Animals; Capsaicin; Cholestasis; Disease Models, Animal; Indoles; Inflammation Mediators; Leukotriene B4; Ligation; Lipoxygenase Inhibitors; Male; Models, Biological; Pancreatitis; Peroxidase; Rats; Rats, Sprague-Dawley; TRPV Cation Channels

This study was designed to evaluate the protective effect of the cysteinyl leukotriene receptor antagonist montelukast against pancreatic injury during acute pancreatitis.. Acute pancreatitis was induced in rats by 20-μg/kg (intraperitoneal) cerulein given at 1-hour intervals within 4 hours. Montelukast was administered intraperitoneally at a dose of 10 mg/kg 15 minutes before the first cerulein injection. Six hours after the cerulein or saline injections, the animals were killed by decapitation. Blood samples were collected to analyze amylase, lipase, and the proinflammatory cytokines tumor necrosis factor α and interleukin 1β. Pancreas tissues were taken for the determination of tissue glutathione and malondialdehyde levels and Na,K-adenosine triphosphatase and myeloperoxidase activities. The extent of tissue injury was analyzed microscopically.. Acute pancreatitis caused significant decreases in tissue glutathione level and Na,K-adenosine triphosphatase activity, which were accompanied with significant increases in the pancreatic malondialdehyde level, myeloperoxidase activity, and plasma cytokine level. On the other hand, montelukast treatment reversed all these biochemical indices and histopathological alterations that were induced by cerulein.. These results suggest that cysteinyl leukotrienes may be involved in the pathogenesis of acute pancreatitis and that the cysteinyl leukotriene receptor antagonist, montelukast, might be of therapeutic value for treatment of acute pancreatitis.

Topics: Acetates; Acute Disease; Animals; Ceruletide; Cyclopropanes; Cytokines; Female; Glutathione; Leukotriene Antagonists; Leukotriene B4; Lipid Peroxidation; Male; Pancreas; Pancreatitis; Peroxidase; Quinolines; Rats; Rats, Sprague-Dawley; Receptors, Leukotriene; Sodium-Potassium-Exchanging ATPase; Sulfides

Pancreatic cancer has an abysmal prognosis. Targets for early detection, prevention and therapy are desperately needed. Inflammatory pathways have an important impact on tumour growth and progression. Expression of BLT2 (the second leukotriene B(4) receptor) was investigated by real-time RT-PCR and immunohistochemistry. Cell proliferation was studied after stable transfection with BLT2, after treatment with siRNA and Compound A as an agonist. BLT2 is expressed in all pancreatic cancer cell lines. Results from real-time RT-PCR revealed significant overexpression of BLT2 in malignant intraductal papillary mucinous neoplasias (IPMNs) and pancreatic adenocarcinoma. Intense staining was evident in IPMNs, infiltrating tumour cells and advanced pancreatic intraepithelial neoplasias (PanINs) but not in normal ductal cells. Overexpression of BLT2 as well as stimulation of Colo357, Panc-1 and AsPC1 cells with Compound A caused a significant increase in tumour cell proliferation, an effect reversed after siRNA treatment. This study demonstrates for the first time the expression of BLT2 in the pancreas and overexpression in pancreatic cancers and malignant IPMNs in particular. Upregulation of BLT2 is already evident in precursor lesions (PanINs, IPMNs). Overexpression of this receptor leads to significant growth stimulation. Therefore, we suggest BLT2 as a new target for chemoprevention and therapy for pancreatic cancer.

Topics: Base Sequence; Cell Line, Tumor; Cell Proliferation; DNA Primers; Humans; Immunohistochemistry; Leukotriene B4; Ligands; Pancreatic Neoplasms; Pancreatitis; Receptors, Leukotriene B4; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering

Melatonin has been used to treat experimental pancreatitis, although not all the drug's therapeutic mechanisms of melatonin have been defined. Prostaglandins (PGs) are proinflammatory mediators that exert their effects mainly locally during inflammatory diseases. The present study was undertaken to examine whether treatment with melatonin influences local PG production. An acute pancreatitis model in male Sprague-Dawley rats (225-275 g) was established by continuously infusing caerulein (15 mg/kg/hr). Mean arterial pressure and pancreatic perfusion were monitored continuously. Melatonin was delivered via the intraperitoneal route at doses of either 2 or 10 mg/kg, 30 min after caerulein injection. Malondialdehyde and glutathione levels of the pancreas and liver and the trypsinogen activation peptide levels in the serum were measured at the end of the experiment (8 hr after infusion of caerulein). Intraperitoneal injection of melatonin (2 and 10 mg/kg) reduced the reduction in systemic arterial pressure and decreased pancreatic perfusion in the rat model of caerulein pancreatitis. Moreover, melatonin treatment changed local PG production toward control level. Higher dose of melatonin was somewhat more effective in preventing the caerulein-induced alterations than was the lower dose.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Blood Pressure; Ceruletide; Dinoprostone; Glutathione; Leukotriene B4; Male; Malondialdehyde; Melatonin; Microdialysis; Oligopeptides; Pancreas; Pancreatitis; Prostaglandins; Rats; Rats, Sprague-Dawley; Regional Blood Flow

This work studied the effects of hydrocortisone treatment in experimental acute pancreatitis on cytokines, phospholipase A2, and breakdown products of arachidonic acid and survival. Edematous and necrotizing pancreatitis were induced in Wistar rats by cerulein hyperstimulation and retrograde intraductal infusion of sodium taurocholate, respectively. Hydrocortisone (10 mg/kg) was administered intravenously 10 minutes after induction of acute pancreatitis. Serum was assayed for phospholipase A2; interleukin (IL) 1beta, IL-6, IL-10, thromboxane B2; Prostaglandin E2; and leukotriene B4 at five different time points. A significant release of inflammatory mediators was seen only in the severe model. Hydrocortisone powerfully suppressed arachidonic acid breakdown products and only mildly attenuated the systemic increase of phospholipase A2 and pro- and antiinflammatory cytokines. The mortality rate after 72 hr in the severe model was 86%. Hydrocortisone treatment reduced mortality to 13% (P = 0.001; Fisher's exact test). Hydrocortisone seems to be effective in the treatment of the early systemic inflammatory response syndrome associated with severe acute pancreatitis.

Topics: Acute Disease; Animals; Anti-Inflammatory Agents; Cytokines; Dinoprostone; Disease Models, Animal; Female; Hydrocortisone; Leukotriene B4; Pancreatitis; Rats; Rats, Wistar; Systemic Inflammatory Response Syndrome; Thromboxane B2

The role of 5-lipoxygenase metabolites of arachidonic acid in the inflammatory response associated with experimental acute pancreatitis has been evaluated. For this purpose, an experimental necrohemorrhagic pancreatitis was induced in rats by intraductal administration of 5% sodium taurocholate. Neutrophil infiltration was detected in pancreas at 1 and 3 h after the induction of pancreatitis. This was concomitant with increased levels of leukotriene B4 and peptide leukotrienes (C4, D4 and E4). In lung, similar increases in neutrophil infiltration were detected but only 3 h after acute pancreatitis induction, and no changes in leukotriene B4 nor peptide leukotrienes were apparent at this time. These results suggest that after induction of acute pancreatitis, 5-lipoxygenase metabolites could play a role in the inflammatory response in the pancreas, but they are not involved in the inflammatory response in lung.

Topics: Acute Disease; Animals; Disease Models, Animal; Leukotriene B4; Leukotrienes; Lipase; Lung; Male; Neutrophils; Pancreas; Pancreatitis; Peroxidase; Rats; Rats, Wistar; Taurocholic Acid

In the present investigation we studied the concerted role of superoxide anion, platelet activating factor (PAF) and leukotriene B4 (LTB4) in the mechanism that results in polymorphonuclear leucocyte accumulation induced by oxygen free radicals in rat pancreas. This was done by comparing the effects of a PAF antagonist (BN-52021), a LTB4 inhibitor (MK-886) and superoxide dismutase (SOD) in a experimental rat model of inflammation elicited by the oxygen free radicals induced via infusion of xanthine/xanthine oxidase. Also, the effect of independent LTB4 infusion has been studied. The results show that increases in polymorphonuclear cell infiltration (evaluated by tissue histology), myeloperoxidase and LTB4 levels induced in pancreas by infusion of xanthine/xanthine oxidase were abolished by the administration of either the PAF antagonist, the LTB4 inhibitor, or SOD. The fact that BN-52021 could prevent neutrophil recruitment and LTB4 synthesis suggests that PAF is a necessary step for subsequent LTB4 synthesis and polymorphonuclear leucocyte accumulation.

Topics: Animals; Diterpenes; Free Radicals; Ginkgolides; Indoles; Lactones; Leukotriene B4; Lipase; Male; Neutrophils; Pancreas; Pancreatitis; Peroxidase; Platelet Activating Factor; Rats; Rats, Wistar; Superoxide Dismutase; Superoxides; Xanthine; Xanthine Oxidase; Xanthines

The role of nitric oxide in lipoxygenase metabolism after a process of ischemia-reperfusion in pancreas transplantation has been evaluated in this study. Sprague-Dawley rats were randomized into three groups, as follows: Group I--Control animals not surgically manipulated; Group II.--Pancreas transplantation, after 12 h of organ preservation; Group III.--Same as II but with administration of NG-nitro-L-arginine methyl esther (a nitric oxide synthase inhibitor) (10 mg/Kg) prior to organ revascularization. The results show post-transplantation increases in leukotriene B4 and 12-hydroxyeicosatraenoic acid levels in pancreatic tissue. Nitric oxide synthase inhibition reversed the increases in 12-hydroxyeicosatetraenoic acid, but was unable to modify leukotriene B4 increases suggesting the existence of a direct effect of nitric oxide on the 12-lipoxygenase metabolism in pancreas transplantation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Acute Disease; Animals; Arachidonate 12-Lipoxygenase; Enzyme Activation; Enzyme Inhibitors; Free Radicals; Gene Expression Regulation; Ischemia; Leukotriene B4; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Organ Preservation; Pancreas; Pancreas Transplantation; Pancreatitis; Rats; Rats, Sprague-Dawley; Reperfusion Injury

The implication of different eicosanoids and oxygen free radicals in the development of pancreatic injury after an ischemia-reperfusion process has been evaluated. For this purpose we have compared the effect of allopurinol and indomethacin administration on the pancreatic levels of eicosanoids in a rat model of pancreatic ischemia-reperfusion. After 60 min of pancreatic ischemia and 2 h of reperfusion, significant increases in 6-keto-PGF1 alpha, PGE2, and LTB4 in pancreas tissue were detected. Allopurinol before the ischemic period reduced 6-keto-PGF1 alpha, PGE2, and LTB4 levels to the range of basal values, while prior indomethacin treatment significantly reduced 6-keto-PGF1 alpha and PGE2 levels, with LTB4 remaining unmodified. Increased postischemic plasma lipases were also significantly reduced by allopurinol to the range of sham-operated animals whereas indomethacin did not modify these levels. The data suggest a role for lipoxygenase metabolites in the development of pancreatic injury and the importance of the enzyme xanthine oxidase as an inductor of eicosanoid biosynthesis.

Topics: 6-Ketoprostaglandin F1 alpha; Allopurinol; Animals; Biomarkers; Cyclooxygenase Inhibitors; Dinoprostone; Free Radicals; Indomethacin; Ischemia; Leukotriene B4; Lipase; Lipoxygenase; Male; Oxidative Stress; Pancreas; Pancreatitis; Rats; Rats, Wistar; Reactive Oxygen Species; Reperfusion Injury; Xanthine Oxidase

Pancreatic production of lipid mediators of inflammation, including eicosanoids and platelet-activating factor (PAF), was examined in two models of pancreatitis in the rat. Chronic pancreatitis was induced by ligation of the pancreatic duct and acute pancreatitis by infusion of sodium taurocholate into the pancreatic duct. In the model of chronic pancreatitis, prostaglandin E2 (PGE2), PGD2, 6-keto PGF1 alpha, thromboxane B2 (TXB2), and PAF increased significantly in the pancreas in a similar fashion, whereas leukotriene B4 (LTB4) remained unchanged. BN52021, a PAF antagonist, reduced the accumulation of pancreatic TXB2, 6-keto PGF1 alpha, and PGD2, and did not affect PGE2. In the model of acute pancreatitis, LTB4 increased, whereas PGE2, TXB2, and 6-keto PGF1 alpha decreased significantly; PGD2 changed slightly; and PAF was undetectable. The present results indicate that mild chronic pancreatitis is accompanied by the production and accumulation of a wide spectrum of lipid mediators while LTB4 was the only lipid mediator detected at biologically active concentrations in the model of severe acute pancreatitis. It is suggested that various mediators are involved in establishing a balance between inflammation and the repair of the inflamed pancreatic tissue observed in mild chronic pancreatitis. While both eicosanoids and PAF are involved in such self-limiting responses to inflammatory challenge, PAF seems to play a central role in instigating the production of the various other mediators detected in the model of chronic pancreatitis. In the model of acute pancreatitis while the deficiency of various lipid mediators may render the pancreatic tissue more susceptible to acute damage, enhanced LTB4 appears to contribute to the destructive pathology observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Acute Disease; Animals; Chronic Disease; Dinoprostone; Diterpenes; Eicosanoids; Ginkgolides; Lactones; Leukotriene B4; Ligation; Male; Masoprocol; Pancreatic Ducts; Pancreatitis; Platelet Activating Factor; Prostaglandin D2; Rats; Rats, Sprague-Dawley; Taurocholic Acid; Thromboxane B2

Several studies have reported that prostanoids are involved in many of the physiopathological mechanisms underlying acute pancreatitis but their precise role in this disease remains to be established. The objective of this work is to evaluate the variation of local tissue production of prostanoids and lipoxygenase metabolites of arachidonic acid in acute pancreas inflammation induced by intraductal administration of 3.5% sodium taurocholate (0.1 ml/100 mg body weight) in rats. Pancreatic tissue levels of leukotriene B4 (LTB4), 15 hydroxyeicosatetraenoic acid (15-HETE), 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha), thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) were determined by HPLC-RIA techniques at 5 and 60 minutes after induction of acute pancreatitis (AP). Prostanoids increased significantly at 5 minutes and LTB4 and 15-HETE at 60 minutes. These data confirm that the prostanoid imbalance could be considered as an early specific response of the pancreas to the inflammatory events characteristic of induced AP while the altered levels of the lipoxygenase products (LTB4 and 15-HETE) would be more of a nonspecific organ response associated to the high cellular infiltration rate and necrosis observed in the late phases of acute pancreatitis.

Topics: 6-Ketoprostaglandin F1 alpha; Acute Disease; Animals; Dinoprostone; Hemorrhage; Hydroxyeicosatetraenoic Acids; Kinetics; Leukotriene B4; Lipoxygenase; Male; Pancreas; Pancreatitis; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Sprague-Dawley; Taurocholic Acid; Thromboxane B2

Topics: Acute Disease; Enzyme Precursors; Humans; Leukocytes; Leukotriene B4; Pancreas; Pancreatic Elastase; Pancreatitis; Tumor Necrosis Factor-alpha