The effects of somatostatin on the microperfusion of the pancreas during acute necrotizing pancreatitis in rats

BACKGROUND/AIMS: Autodigestion and impairment of microcirculation of the pancreas play an important role in the pathogenesis of acute pancreatitis. Somatostatin with the reducing effect on the hepato-splanchnic blood flow decreases exocrine pancreatic secretion. Microcirculatory changes are central to the pathogenesis of acute pancreatitis. However, little is known about the effects of somatostatin on the pancreatic tissue oxygen pressure and acinar cell injury during acute pancreatitis. The aim was to evaluate somatostatin by measuring its effect on the pancreatic tissue oxygen pressure and acinar injury in acute pancreatitis. METHODOLOGY: Acute necrotizing pancreatitis was induced in rats by standardized intraductal bile acid infusion and cerulein hyperstimulation. Serum trypsinogen activation peptide was measured to verify comparable disease severity. After the induction of acute necrotizing pancreatitis, animals randomly received either ringer lactate or somatostatin. Monitoring included cardiorespiratory parameters, hematocrit, amylase, pancreatic tissue oxygen pressure, and trypsinogen activation peptide levels. At the end of the experiments the pancreas was removed for evaluation of acinar cell injury. RESULTS: The two study groups were comparable with regard to mean arterial pressure, heart rate, arterial blood gases, hematocrit, and serum amylase. The induction of pancreatitis resulted in the significant decrease of pancreatic tissue oxygen pressure in both groups. The use of somatostatin did not increase pancreatic tissue oxygen pressure. There were no significant differences in plasma trypsinogen activation peptide and serum amylase levels in the animals of two treatment groups. Only somatostatin decreased pancreatic damage significantly. CONCLUSIONS: The use of somatostatin did not improve pancreatic microcirculation or trypsinogen activation peptide level in acute necrotizing pancreatitis; however, it reduced pancreatic damage. Therefore, it has a limited value in the treatment of the acute pancreatitis.     

Effect of microcirculatory perfusion on distribution of trypsinogen activation peptides in acute experimental pancreatitis

Extraintestinal trypsinogen activation peptides (TAP) have been shown to correlate with severity of acute pancreatitis in humans as well as in various animal models. Ischemia superimposed on experimental pancreatitis, however, increases acinar cell injury without increasing TAP in plasma. We speculated that TAP generated in the pancreas might not reach the circulation in necrotizing pancreatitis due to decreased pancreatic perfusion. To test the hypothesis that generation of TAP in plasma is related to pancreatic perfusion and that plasma TAP may therefore underestimate acinar cell injury in necrotizing disease, we correlated TAP in pancreatic tissue and body fluids with capillary pancreatic blood flow in necrotizing and edematous pancreatitis. The ratio between necrosis and TAP in tissue was similar in both models; the ratio between TAP in plasma and tissue, however, was significantly lower in necrotizing pancreatitis, indicating that a certain amount of TAP generated in the pancreas did not reach the circulation. Decreased pancreatic perfusion found in necrotizing pancreatitis was consistent with this finding. Our data suggest that TAP in tissue is most reliable to indicate severity of acute pancreatitis, whereas plasma TAP may underestimate pancreatic injury in necrotizing disease due to decreased pancreatic perfusion.     

Early bacterial infection of the pancreas and course of disease in cerulein-induced acute pancreatitis in rats

BACKGROUND: Bacterial infection of the pancreas aggravates the course of acute pancreatitis. Since bacterial translocation from the gut is likely to be an early event, in an animal model of pancreatitis, we investigated the effect of early bacterial supra-infection of the pancreas on the course of the disease. METHODS: Six hours after the induction of acute pancreatitis in male Wistar rats (n = 180) by supramaximal stimulation with cerulein (or placebo in a control group), the animals were operated and a suspension of Helicobacter pylori, Escherichia coli or saline were introduced either in the pancreatic duct or interstitium (12 groups of 15 rats each); after 24 h, animals were killed and the following parameters analysed: macroscopic and histologic appearance of the pancreas (score), wet-to-dry weight ratio, pancreas trypsinogen activation peptide level, serum amylase, interleukin-6 and phospholipase A2 activity. RESULTS: All parameters were increased in rats with cerulein-induced pancreatitis in comparison to placebo. Interstitial and intraductal application of bacteria increased the pancreatic damage. This effect was more evident with the application of E. coli in both cerulein and placebo groups. Application of E. coli but not of H. pylori determined pancreatic activation of trypsinogen, increased mortality and induced the production of interleukin-6. CONCLUSIONS: Bacterial invasion of the pancreas worsens the histologic and clinical picture of disease and induces a systemic inflammatory response.     

Transgenic expression of pancreatic secretory trypsin inhibitor-I ameliorates secretagogue-induced pancreatitis in mice

BACKGROUND & AIMS: Endogenous trypsin inhibitors are believed to inhibit protease activity if trypsin becomes inadvertently activated within the acinar cell. However, this action remains unproven, and the role of endogenous pancreatic trypsin inhibitors in acute pancreatitis is unknown. In this study, we tested whether increased levels of pancreatic secretory trypsin inhibitor-I (PSTI-I) in mice could prevent secretagogue-induced pancreatitis. METHODS: Rat PSTI-I expression was targeted to pancreatic acinar cells in transgenic mice by creating a minigene driven by the rat elastase I enhancer/promoter. Secretagogue-induced pancreatitis was achieved by 12 hourly intraperitoneal injections of caerulein. The severity of pancreatitis was assessed by measurements of serum amylase, histologic grading, and pancreas wet weight-to-body weight ratio. Trypsinogen activation and trypsin activity were measured in pancreatic extracts. RESULTS: Targeted expression of PSTI-I to the pancreas increased endogenous trypsin inhibitor capacity by 190% (P <.01) in transgenic vs. nontransgenic mice. Caerulein administration to nontransgenic mice produced histologic evidence of acute pancreatitis, and significantly elevated serum amylase and pancreas weight ratio. In caerulein-treated transgenic mice, the histologic severity of pancreatitis was significantly reduced. There was no difference in trypsinogen activation peptide levels between caerulein-treated transgenic and nontransgenic mice. However, trypsin activity was significantly lower in transgenic mice receiving caerulein compared with nontransgenic mice. CONCLUSIONS: These data demonstrate that the severity of secretagogue-induced pancreatitis is significantly ameliorated in mice with higher pancreatic levels of trypsin inhibitor. We propose that PSTI-I prevents pancreatitis by inhibiting the activity of trypsin, rather than by reducing trypsinogen activation.     

Activation of proteases in cerulein-induced pancreatitis

The activation of zymogen proteases and lysosomal enzyme cathepsin B in the pancreas was investigated in cerulein-induced pancreatitis in rats. Acute pancreatitis was induced by two intraperitoneal injections of 40 micrograms/kg of body weight of cerulein at intervals of 1 h. After the first cerulein injection, the active trypsin and elastase contents in the pancreas tissues significantly increased, and reached the highest level at 3 h after the first injection, followed by peaks at 5 h in the serum amylase and lipase levels and the pancreas wet weight. Cathepsin B contents in pancreas tissues showed a parallel increase with active zymogen enzymes during the first 3 h of pancreatitis. These findings may suggest that the intracellular activation of trypsinogen is an important step in the development of cerulein-induced acute pancreatitis and that cathepsin B plays a role in the activation of trypsinogen in pancreatic acinar cells.     

Trypsin-based laboratory methods and carboxypeptidase activation peptide in acute pancreatitis

Acute pancreatitis is a common disease varying widely in severity. At present, there is no "gold standard" for the diagnosis of acute pancreatitis. Currently, the diagnosis of acute pancreatitis is based on measurements of serum amylase and/or lipase activity, which are considered unsatisfactory due to their low level of accuracy. Early identification of acute pancreatitis and especially detection of patients with a severe form of the disease is of utmost importance. Premature intrapancreatic activation of trypsinogen is a crucial early event in the pathophysiology of acute pancreatitis. The conversion of trypsinogen to active trypsin is mediated by the release of its activation peptide (TAP). The active trypsin is then able to activate other pancreatic zymogens (i.e. procarboxypeptidase) leading to tissue damage and eventually to autodigestion of the pancreas. To improve the laboratory diagnostics of AP, new methods have been developed to measure this primary pancreatic proteolytic insult. Here we review the current knowledge and clinical implications of trypsin based laboratory methods and carboxypeptidase activation peptide (CAPAP) in the diagnosis and severity assessment of acute pancreatitis.     

Role of serum pancreatic enzyme assays in diagnosis of pancreatic disease

The serum behavior of amylase, pancreatic isoamylase, lipase, trypsinogen, and elastase 1 was studied in 145 patients with pancreatic disease and in 66 patients with abdominal pain of nonpancreatic origin, for the purpose of evaluating the relative diagnostic utility of their assays. In 34 patients with acute pancreatitis, serum lipase, trypsinogen, and elastase 1 were elevated in all 34, pancreatic isoamylase in 33 (97%) and amylase in 30 (88%). Ten of these acute pancreatitis patients were followed sequentially for seven days: the variations in their serum enzyme levels were parallel, although the lipase, trypsinogen, and particularly the elastase 1 elevations persisted longer than did those of amylase and pancreatic isoamylase. Among the patients with chronic pancreatitis, either in painful relapse (N=19) or with pancreatic cysts (N=15), the respective percentages of enzymes elevations were: 79 and 80% for elastase 1, 68 and 67% for trypsinogen, 63 and 73% for pancreatic isoamylase, 58 and 60% for lipase, 53 and 60% for amylase. In the 52 chronic pancreatitis patients studied during clinical remission, serum enzyme behavior varied greatly, and a majority of the assays (60%) were normal; even in the case of severe pancreatic exocrine insufficiency, normal as well as abnormally high and low enzyme values were seen. Highly variable enzyme behavior was also seen in the 40 patients with pancreatic cancer, and elastase I was the most frequently (35%) elevated enzyme in this group as well. Among the patients with abdominal pain of nonpancreatic origin, abnormally high enzyme levels were present in percentages ranging from 6% for lipase to 21% for trypsinogen. These data indicate that serum pancreatic enzyme assays are of value in establishing the diagnosis of acute pancreatitis and a relapse or cystic complication of chronic pancreatitis. In the case of pancreatic cancer or of chronic pancreatitis in clinical remission, the diagnostic role of the studied enzymes is rather limited.Partially supported by the Italian Ministry of Public Education Funds in 1985.     

On the protective mechanisms of nitric oxide in acute pancreatitis

Background—Ectopic proteaseactivation, microcirculatory changes, and leucocyte activation are themain events in the pathogenesis of acute pancreatitis. Nitric oxide(NO) is known to be a key mediator in the normal and inflamed pancreas.
Aims—To investigate the targets onwhich NO exerts its effect in caerulein induced pancreatitis.
Methods—Acute pancreatitis wasinduced in rats which additionally received either the NO synthasesubstrate, L-arginine; the NO donor, sodium nitroprusside;or the NO synthase inhibitor, N-nitro-L-arginine methylester (L-NAME). At six hours, pancreatic injury (oedema,leucocyte content, ectopic trypsinogen activation) was analysed andpancreatic oxygenation and perfusion were determined. A directinfluence of NO on amylase secretion and trypsinogen activation wasevaluated separately in vitro.
Results—Both NO donors reduced thegrade of inflammation. L-NAME increased the severity ofinflammation, while decreasing pancreatic tissue oxygenation. Althoughneither amylase secretion nor intracellular trypsinogen activation incaerulein stimulated pancreatic acini was influenced by either NOdonors or inhibitors, both NO donors decreased intrapancreatictrypsinogen activation peptide (TAP) and pancreatic oedema in vivo, andL-NAME increased TAP.
Conclusions—NO protects againstinjury caused by pancreatitis in the intact animal but has nodiscernible effect on isolated acini. It is likely that in pancreatitisNO acts indirectly via microcirculatory changes, including inhibitionof leucocyte activation and preservation of capillary perfusion.

Keywords:acute pancreatitis; nitric oxide; microcirculation; leucocytes; pancreatic secretion

     

Sphincter of Oddi dysfunction produces acute pancreatitis in the possum

BACKGROUND: Sphincter of Oddi dysfunction has been implicated as a cause of various forms of acute pancreatitis. However, there is no direct evidence to show that sphincter of Oddi dysfunction can cause obstruction of trans-sphincteric flow resulting in acute pancreatitis. AIMS: To determine if induced sphincter of Oddi spasm can produce trans-sphincteric obstruction and, in combination with stimulated pancreatic secretion, induce acute pancreatitis. METHODS: In anaesthetised possums, the pancreatic duct was ligated and pancreatic exocrine secretion stimulated by cholecystokinin octapeptide/secretin to induce acute pancreatitis. In separate animals, carbachol was applied topically to the sphincter of Oddi to cause transient sphincter obstruction. Sphincter of Oddi motility, trans-sphincteric flow, pancreatic duct pressure, pancreatic exocrine secretion, plasma amylase levels, and pancreatic tissue damage (histology score) were studied and compared with variables in ligation models. RESULTS: Acute pancreatitis developed following stimulation of pancreatic exocrine secretion with peptides after pancreatic duct ligation (p<0.05). Neither pancreatic duct ligation nor stimulation of pancreatic exocrine secretion with cholecystokinin octapeptide/secretin alone resulted in acute pancreatitis. Topical carbachol stimulated sphincter of Oddi motility abolished trans-sphincteric flow, and increased pancreatic exocrine secretion (p<0.05) and pancreatic duct pressure to levels comparable with pancreatic duct ligation (p<0.001). Carbachol application (with or without combined peptide stimulation) elevated plasma amylase levels (p<0.01) and produced pancreatic tissue damage (p<0.05). Decompression of pancreatic duct ameliorated these effects (p<0.05). CONCLUSION: Induced sphincter of Oddi dysfunction when coupled with stimulated pancreatic secretion causes acute pancreatitis. This may be an important pathophysiological mechanism causing various forms of acute pancreatitis.     

Pseudomonas pneumonia-mediated sepsis induces expression of pancreatitis-associated protein-I in rat pancreas

Severe impairment of exocrine pancreatic secretion has recently been demonstrated in a clinical study in sepsis and septic shock patients. The purpose of this study was to further evaluate involvement of the pancreas in the acute phase reaction in sepsis. Using a normotensive rat model of Pseudomonas pneumonia-induced sepsis, we assessed the expression of PAP-I, amylase and trypsinogen mRNA, PAPI protein levels, and cytokine expression in the pancreas by Northern and Western blot analysis and RT-M PCR, respectively. Presence of several well-established features of pancreatitis in sepsis-induced animals were examined by biochemical and histopathological methods as well as by a determination of both water and myeloperoxidase content. Sepsis resulted in an up-regulation of PAP-I gene expression and increase in its protein level in pancreas while the mRNA levels of amylase and trypsinogen were down-regulated. Differences in the pancreatic cytokine expression, serum amylase and serum lipase levels, the occurrence of pancreatic edema as well as the severity of inflammatory infiltration and necrosis were not significantly different between sham and pneumonia groups. Acinar cells showed increased vacuolization in pneumonia animals 24 hours after the treatment. These findings demonstrate that the pancreas is actively involved in the acute phase reaction in sepsis of remote origin. This involvement occurs without concomitant biochemical and histopathologic alterations observed in pancreatitis. Taken all together, these features are indicative of a sepsis-specific dysfunction of the pancreas.     

Effects of melatonin on acute necrotizing pancreatitis in rats

The aim of this study was to investigate the influence of melatonin on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. The induction of ANP resulted in significant increases in mortality rate, pancreatic necrosis and increased serum activity of amylase, alanine aspartate transferase (ALT), interleukin 6 (IL-6), lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, serum concentration of urea, tissue activity of myeloperoxidase (MPO) and malondialdehyde (MDA) in the pancreas and lung, and significant decrease of concentrations of calcium, blood pressure, urine output and pO (2). Melatonin inhibited the changes in blood pressure, urine output, pO (2), serum concentration of urea, and calcium, tissue activity of MPO and MDA in the pancreas and lung, LDH level in BAL fluid, and partially reduced serum activity of IL-6. Melatonin did not change serum activity of amylase, ALT, pancreatic damage and the mortality rate. The use of melatonin has a limited value on the course of ANP. It may be useful as a supportive treatment during ANP.     

Studies on Serum Amylase in Normal Man and in Acute Pancreatitis

Summary: Studies on serum amylase in normal man and in acute pancreatitis. I. L MacGregor and D. Zakim, Aust. N.Z. J. Med. 1976, 6, pp. 551–556.
Amylase isoenzymes in serum, urine, saliva, jejunal juice, and pancreatic tissue were separated by isoelectric focusing. Isoamylase patterns obtained indicated that the majority of amylase activity in normal serum is of salivary gland origin. Pancreatic amylase is characteristically predominant in acute pancreatitis. The increased renal clearance of amylase in acute pancreatitis may be partly due to the increased proportion of the smaller molecular weight pancreatic amylase. However, a demonstrated increase in the renal clearance of salivary amylase in acute pancreatitis suggests a renal cause also. Autopsy pancreas samples devoid of TAME (p-tosyl arginine methyl ester) esterase activity (e.g. trypsin and plasma enzymes such as thrombin and pi asm in) had isoenzyme patterns different to those samples with free proteolytic activity. Incubation of TAME esterase free pancreas with trypsin caused conversion of the former isoamylase
pattern to one with the predominant isoenzymes focusing coincident with the predominant peak in serum from acute pancreatitis, jejunal aspirate, and TAME esterase positive autopsy pancreas. Such conversion suggests that pancreatic amylase is synthesized in a form different from that found in the intestinal lumen and serum.     

Mechanism and role of trypsinogen activation in acute pancreatitis

In healthy subjects, the 3 known pancreatic trypsinogens, which are endopeptidases belonging to the chymotrypsin superfamily, are activated by enterokinase and partial autoactivation in the duodenum. The premature activation of trypsinogen in the pancreatic interstitium, with the subsequent activation of other pancreatic zymogens, is believed to lead to the autodigestion of the gland, this being the first event in acute pancreatitis. The mechanisms that lead to trypsinogen, activation in acute pancreatitis are largely unknown. However, ischemia, hypercalcemia and the activation of cathepsin B (by cholecystokinin) are thought to be of importance. The easiest and most reliable way to assess trypsinogen activation is the measurement of the activation peptide, TAP, in urine, plasma, pancreatic tissue or ascitic fluid. In the animal model of acute pancreatitis, TAP in ascites and pancreatic tissue has been shown to correlate with the presence and extent of necroses. It has proven to be a good marker for the severity of pancreatitis and is a useful marker in examining the pathophysiology and possible treatment modalities in the animal model of acute pancreatitis. Studies on TAP in human acute pancreatitis were most commonly focused on urinary TAP. Within a 48-hour time frame after the onset of the disease, TAP was a good predictor of the severity of acute pancreatitis. The main advantage over other markers, such as CRP, is that TAP is the earliest marker of necrosis to be increased. Also, increased levels of TAP in ascitic fluid were shown to correlate well with pancreatic necroses. In our experience, plasma TAP was found to have a "diagnostic window" within the first 3 days predicting pancreatic necroses. Positive TAP gave a very good positive prediction and a high specificity towards the development of pancreatic necroses, but did not differ between necrotizing pancreatitis with systemic complications or uncomplicated necrotizing pancreatitis. We therefore think that plasma TAP is a very good marker for local complication in acute pancreatitis and its routine measurements may help to identify patients at a high risk within the first days of the disease.     

Cytoprotective effects of prostaglandins and a new potent protease inhibitor in acute pancreatitis.

The redistribution of cathepsin B, a lysosomal enzyme, from the lysosomal pellet to the zymogen pellet in the subcellular fractionation, the colocalization of cathepsin B with digestive enzyme, and increased cellular, lysosomal, and mitochondrial fragility within acinar cells have been found during the early stages of caerulein-induced acute pancreatitis in rats. In the present study, the authors investigated the protective effects of prostaglandin E1 and E2, a combined therapy of these prostaglandins, and a new, synthetic, low molecular weight protease inhibitor, ONO3307, on the exocrine pancreas in this noninvasive model of experimental pancreatitis in vivo and in vitro. Prostaglandin E2, but not E1, prevented hyperamylasemia, congestion of amylase and trypsinogen in the acinar cells, redistribution of cathepsin B, and amylase and lactate dehydrogenase discharge from the dispersed acini. It also prevented cathepsin B leakage from the lysosomes and malate dehydrogenase leakage from the mitochondria in an almost dose-dependent manner, particularly at the dose of 100 micrograms/kg/hr continuous infusion. Furthermore, the combined therapy of prostaglandin E2 with ONO3307 strongly inhibited all the parameters tested in this study. This combination therapy seems to be the most effective against secretagogue-induced pancreatic injuries. These results indicate that cellular and subcellular organellar fragility seem to be closely involved in the pathogenesis of acute pancreatitis. Prostaglandin E2 seems to have important cytoprotective effects on the biologic membranes, such as a stabilizer of lysosomal or mitochondrial membranes. In addition, these findings also suggest the crucial roles of some unknown proteases in the etiology of acute pancreatitis, and indicate the clinical effectiveness of prostaglandins and this type of low molecular weight protease inhibitor for acute pancreatitis.     

Acute pancreatitis： Etiology and common pathogenesis

Acute pancreatitis is an inflammatory disease of the pancreas. The etiology and pathogenesis of acute pancreatitis have been intensively investigated for centuries worldwide. Many causes of acute pancreatitis have been discovered, but the pathogenetic theories are controversial. The most common cause of acute pancreatitis is gallstone impacting the distal common bile-pancreatic duct. The majority of investigators accept that the main factors for acute billiary pancreatitis are pancreatic hyperstimulation and bile-pancreatic duct obstruction which increase pancreatic duct pressure and active trypsin reflux.Acute pancreatitis occurs when intracellular protective mechanisms to prevent trypsinogen activation or reduce trypsin activity are overwhelmed. However, little is known about the other acute pancreatitis. We hypothesize that acute biliary pancreatitis and other causes of acute pancreatitis possess a common pathogenesis. Pancreatic hyperstimulation and pancreatic duct obstruction increase pancreatic duct pressure, active trypsin reflux, and subsequent unregulated activation of trypsin within pancreatic acinar cells. Enzyme activation within the pancreas leads to auto-digestion of the gland and local inflammation. Once the hypothesis is confirmed, traditional therapeutic strategies against acute pancreatitis may be improved. Decompression of pancreatic duct pressure should be advocated in the treatment of acute pancreatitits which may greatly improve its outcome.     

A proinflammatory, antiapoptotic phenotype underlies the susceptibility to acute pancreatitis in cystic fibrosis transmembrane regulator (-/-) mice

BACKGROUND & AIMS: Cystic fibrosis transmembrane regulator (CFTR) gene mutations are associated with pancreatic insufficiency and pancreatitis. Chronic pancreatitis, including cystic fibrosis-related disease, may exist as a continuum between acute and chronic disease and may manifest as recurrent pain. We hypothesized that cftr(m1UNC) (-/-) mice, which have no evidence of chronic pancreatitis, are susceptible to developing acute pancreatitis. METHODS: We used a cerulein hyperstimulation model of acute pancreatitis and measured histological changes, tissue edema, neutrophil infiltration, inflammatory mediators' mRNA expression, apoptosis markers, and pancreatic trypsin and serum lipase activities. Additionally, we quantitated in vivo pancreatic secretion and pancreatic digestive enzymes. RESULTS: Multiple proinflammatory cytokine genes were constitutively overexpressed in cftr (-/-) pancreas compared with wild-type mice. During acute pancreatitis, cftr (-/-) mice developed more severe acute pancreatitis than wild-type, as indicated by greater pancreatic edema, neutrophil infiltration, mRNA expression of multiple inflammatory mediators, and less apoptotic cell death. In contrast to wild-type mice, cftr (-/-) mice had blunted increases in pancreatic trypsin and serum lipase activities, but similar percentages of pancreatic trypsinogen activation. Finally, cftr (-/-) mice had less in vivo pancreatic secretion in response to cholecystokinin octapeptide and reduced pancreatic digestive enzyme protein and mRNA levels, thus suggesting mild pancreatic insufficiency. CONCLUSIONS: A baseline proinflammatory state and an antiapoptotic phenotype may sensitize cftr (-/-) mice to developing more severe acute pancreatitis with an exuberant pancreatic inflammatory response. Cftr (-/-) mice have mild pancreatic insufficiency, which partially explains the blunted increase of pancreatic and serum digestive enzymes during acute pancreatitis. These findings may explain the susceptibility to acute pancreatitis in persons with classic and nonclassic cystic fibrosis.     

Does stress play a role in the development of severe pancreatitis in rats?

The purpose of this study was to investigate whether stress plays a role, morphologically and enzymatically, in the development of severe pancreatitis in rats. Acute hemorrhagic pancreatitis was induced by two intraperitoneal injections of cerulein (40 micrograms/kg body wt) at intervals of 1 h under water-immersion stress for 5 h, whereas water-immersion stress alone did not induce any morphologic and enzymatic changes in the pancreas. In this model, hemorrhagic pancreatitis developed continuously, and the serum amylase level and activation of zymogen proteases in pancreatic tissue were significantly higher than in cerulein-induced pancreatic tissue 5 h after the first cerulein injection. Furthermore, the effects of cerulein on the serum amylase level and activation of zymogen proteases were dose related. Even 5 micrograms/kg body wt of cerulein, which did not induce any evident edematous change in the pancreas, could activate the zymogen proteases of pancreatic tissue fairly well under water-immersion stress compared with pancreatitis induced by 40 micrograms/kg body wt of cerulein alone. These results indicate that stress accelerates the activation of zymogen proteases induced by cerulein and suggest the possibility that stress may play some role in the development of severe pancreatitis.     

Suppression of transforming growth factor beta signalling aborts caerulein induced pancreatitis and eliminates restricted stimulation at high caerulein concentrations

BACKGROUND: Transforming growth factors betas (TGF-betas) are implicated in pancreatic tissue repair but their role in acute pancreatitis is not known. To determine whether endogenous TGF-betas modulate the course of caerulein induced acute pancreatitis, caerulein was administered to wild-type (FVB-/-) and transgenic mice that are heterozygous (FVB+/-) for expression of a dominant negative type II TGF-beta receptor. METHODS: After 7 hourly supramaximal injections of caerulein, the pancreas was evaluated histologically and serum was assayed for amylase and lipase levels. Next, the effects of caerulein on amylase secretion were determined in mouse pancreatic acini, and cholecystokinin (CCK) receptor expression was assessed. RESULTS: The normal mouse pancreas was devoid of inflammatory cells whereas the pancreas from transgenic mice contained lymphocytic infiltrates. Caerulein injection in wild-type mice resulted in 6- and 36-fold increases in serum amylase and lipase levels, respectively, increased serum trypsinogen activation peptide (TAP) levels, gross oedema and a marked inflammatory response in the pancreas that consisted mainly of neutrophils and macrophages. By contrast, FVB+/- mice exhibited minimal alterations in response to caerulein with attenuated neutrophil-macrophage infiltrates. Moreover, acini from FVB+/- mice did not exhibit restricted stimulation at high caerulein concentrations, even though CCK receptor mRNA levels were not decreased. CONCLUSION: Our findings indicate that a functional TGF-beta signalling pathway may be required for caerulein to induce acute pancreatitis and for the CCK receptor to induce acinar cell damage at high ligand concentrations. Our results also support the concept that restricted stimulation at high caerulein concentrations contributes to the ability of caerulein to induce acute pancreatitis.     

Serum pancreatic enzyme behavior during the course of acute pancreatitis

The variations of serum levels of amylase, pancreatic isoamylase, lipase, trypsinogen, and elastase 1 were evaluated in 21 patients with acute pancreatitis. The patients were studied for a mean period of 7 consecutive days (range 5-12 days) after admission to the hospital. On the day of onset of acute pancreatitis, all enzyme levels were abnormally high; pancreatic isoamylase showed the greatest increase compared with its upper normal limit, whereas the increase increment for elastase 1 was the lowest. Subsequently, all enzyme levels except elastase 1 decreased in a parallel fashion. On the eighth day of the study only elastase 1 levels were above normal values in all patients examined, while abnormally high values of lipase were found in 85% of the patients, trypsinogen in 58% of the patients, pancreatic isoamylase in 43%, and total amylase in 23%. These results indicate that, for the early diagnosis of acute pancreatitis, the determination of any of these enzymes is equally efficient, but that elastase 1 is the most sensitive marker of acute pancreatic damage in later stages of the disease.     

Effects of thalidomide in experimental models of post-endoscopic retrograde cholangiopancreatography pancreatitis

BACKGROUND: Tumor necrosis factor-alpha (TNF-alpha) plays a central role in the pathogenesis of acute pancreatitis and related systemic complications. The authors hypothesized that it may also play an important role in the development of pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP). The aim of the study was to evaluate the effectiveness of thalidomide, an immunomodulator that exerts an inhibitory action on TNF-alpha by enhancing mRNA degradation, in reducing post-ERCP pancreatitis in a rat model. METHODS: A total of 200 mg/kg thalidomide was given intragastric once a day (total 8 days) before the experimental models of post-ERCP pancreatitis were established. After 24 h, histology and edema of pancreas, serum amylase, and TNF-alpha mRNA in the pancreatic tissue were evaluated. RESULTS: Intraductal contrast infusion caused increases in serum amylase, edema, histological grade, and TNF-alpha mRNA of pancreas. The prophylactic use of thalidomide significantly reduced serum amylase, pancreatic edema and the histologic grade of pancreatitis accompanied by a decrease in mRNA expression of TNF-alpha in the pancreatic tissue. CONCLUSIONS: Prophylactic intragastric administration of thalidomide provides a protective effect in post-ERCP pancreatitis. The mechanism of the protective effects of thalidomide seems to be the reduction of expression of TNF-alpha mRNA in pancreatic tissue.