Induction Of Experimental Pancreatitis Research Articles

Effectiveness of interleukin-1 receptor antagonist (Anakinra) on cerulein-induced experimental acute pancreatitis in rats

Aim. Acute pancreatitis (AP) is defined as an inflammatory disease of the pancreas. The purpose of this study was to examine the effectiveness of Anakinra on cerulein-induced experimental pancreatitis rat model by using the results of biochemical and histopathological findings. Materials and methods. Cerulein was administered to induce AP in rats. Group 1 was the sham group. Subcutancerulein was injected to the rats in group 2 for experimental pancreatitis group. In groups 3 and 4, 100 and 50 mg/kg intraperitoneal Anakinra were injected after the induction of experimental pancreatitis by subcutaneous cerulein in rats, respectively. Lastly, in group 5, rats were injected with intraperitoneal saline and subcutan cerulean for placebo group. The following parameters were evaluated: histopathological score of pancreatitis, apoptotic index, amylase, lipase, TNF-α levels, IL-1β and the leukocyte count. Results. When the results of serum amylase, lipase, TNF-α and IL-1β levels, the leukocyte count, histopathologic scores and apoptotic indices of control group compared to the results of other groups, the differences exhibited statistical significance (all p < 0.05). On the other hand, when the results of fourth group compared with the results of third group, the data demonstrated statistical insignificance (p > 0.05). However, no any significant differences were found between the results of fourth and fifth groups (p > 0.05). Conclusion. In the light of these results, cerulein is an appropriate agent for experimental AP rat model and Anakinra has a favorable therapeutic effect on acute experimental pancreatitis model. Moreover, Anakinra significantly decreases cerulein-related pancreatic tissue injury and pancreatic apoptosis.

Phenotypic changes in mouse pancreatic stellate cell Ca2+ signaling events following activation in culture and in a disease model of pancreatitis

The specific characteristics of intracellular Ca 2+ signaling and the downstream consequences of these events were investigated in mouse pancreatic stellate cells (PSC) in culture and in situ using multiphoton microscopy in pancreatic lobules. PSC undergo a phenotypic transformation from a quiescent state to a myofibroblast-like phenotype in culture. This is believed to parallel the induction of an activated state observed in pancreatic disease such as chronic pancreatitis and pancreatic cancer. By day 7 in culture, the complement of cell surface receptors coupled to intracellular Ca 2+ signaling was shown to be markedly altered. Specifically, protease-activated receptors (PAR) 1 and 2, responsive to thrombin and trypsin, respectively, and platelet-derived growth factor (PDGF) receptors were expressed only in activated PSC (aPSC). PAR-1, ATP, and PDGF receptor activation resulted in prominent nuclear Ca 2+ signals. Nuclear Ca 2+ signals and aPSC proliferation were abolished by expression of parvalbumin targeted to the nucleus. In pancreatic lobules, PSC responded to agonists consistent with the presence of only quiescent PSC. aPSC were observed following induction of experimental pancreatitis. In contrast, in a mouse model of pancreatic disease harboring elevated K-Ras activity in acinar cells, aPSC were present under control conditions and their number greatly increased following induction of pancreatitis. These data are consistent with nuclear Ca 2+ signaling generated by agents such as trypsin and thrombin, likely present in the pancreas in disease states, resulting in proliferation of "primed" aPSC to contribute to the severity of pancreatic disease.

HMGB1 targeted immunotherapy provides unique protection against the local and systemic effects of acute pancreatitis

Introduction: HMGB1 is a novel pro-inflammatory cytokine that contributes to sepsis associated lethality. Therapies directed against HMGB1, including ethyl pyruvate, improve outcomes in experimental sepsis. This benefit is maintained even with delayed administration of therapy. We have recently demonstrated that HMGB1 is elevated for up to 3 days after the induction of experimental pancreatitis. We hypothesized that HMGB1 targeted therapy would improve outcomes in acute pancreatitis. Methods: Pancreatitis was induced using intraperitoneal (IP) L-Arginine at a dose of 500mg/100g body weight, in adult male sprague dawley rats (n = 30). The animals were divided into 3 groups; Control - treatment with normal saline IP (n = 10), Treatment 1 - treatment with Ethyl Pyruvate IP 100mg/kg (n = 10) and Treatment 2 - 24hr delayed treatment with Ethyl Pyruvate IP 100mg/kg (n = 10). All animals were sacrificed at 72hrs. Pancreas and serum were analysed for HMGB1 expression. Histological specimens of pancreas and lung were assessed as well as broncho-alveolar lavage protein content. Results; There was a 50% reduction in HMGB1 in the pancreas and serum of the treated groups. Reduced HMGB1 expression correlated with improved pancreatic histological scoring as well as improved bronchoalveolar lavage protein concentration. These beneficial effects were maintained even when the commencement of therapy was delayed for 24hrs. Conclusion: These results show for the first time the unique potential of HMGB1 directed therapy in the treatment of pancreatitis. Its delayed temporal kinetics make it an unprecedented target of anti-inflammatory therapeutics.

Cholecystokinin fails to promote pancreatic regeneration in diabetic rats following the induction of experimental pancreatitis

The aim of the present study was to investigate the spontaneous and cholecystokinin-octapeptide (CCK-8)-promoted laboratory changes and morphological alterations in rats with arginine (Arg)-induced pancreatitis in which diabetes had been induced with streptozotocin (STZ). Male Wistar rats were used in our experiments. Pancreatitis was induced by arginine, diabetes by STZ and regeneration was promoted by CCK-8. The serum amylase, glucose and insulin levels, the pancreatic contents of protein, DNA, amylase, trypsinogen and lipase, the pancreatic weight/body- weight ratio (pw/bw) and the plasma glucagon level were examined 1, 3, 7, 14 and 28 days after pancreatitis induction. Pancreatic tissue samples were examined by light microscopy and immunostaining on paraffin-embedded sections. The insulin and glucagon-containing cells were visualized by using monoclonal antibodies. The administration of low doses of CCK-8 accelerated the processes of regeneration following Arg-induced pancreatitis, but in rats that were also diabetic, pancreatic regeneration was not observed. The administration of low doses of CCK-8 seems to reduce the pancreatic β -cell number and function in diabetic rats. The pancreatic endocrine function was further deteriorated by simultaneous Arg-induced pancreatitis. The diabetic state appeared to shift the normal pancreatic enzyme content (decreased amylase and increased trypsinogen) in this study.

Cytokines and acute pancreatitis

Cytokines have been shown to play a pivotal role in multiple organ dysfunction, a major cause of death in severe acute pancreatitis. Moreover, the two-hit hypothesis of the cytokine-induced systemic inflammatory response syndrome explains the variable individual response to severe acute pancreatitis and the impact of secondary events such as sepsis or therapeutic intervention. Many experimental anti-cytokine therapies have been administered following induction of experimental pancreatitis, and have proved to be therapeutic. Patients with severe pancreatitis present early because of pain. Clearly then a window for therapeutic intervention is available between onset of symptoms and peak pro-inflammatory cytokine expression. It is this fundamental observation that convinces many in the field that the treatment of AP will be one of the first clinical successes for novel drugs or therapy that seek to modulate the inflammatory response.

Experimental models of acute pancreatitis and their relevance to human disease.

There are no experimental models which mimic the most common causes of human acute pancreatitis, i.e. gallstones and alcohol abuse. However, existing models can reproduce the morphology and physiological derangements of certain phases of the illness. Current models have been useful in elucidating the earliest events involved in the initiation and progression of pancreatitis. However, very few animal studies demonstrate effective therapeutic intervention when treatment is given after the induction of experimental pancreatitis. Since immediate intervention is unachievable in human disease, most experimental therapies have not been successfully applied to clinical disease.

Characterization of a rat pancreatic secretory protein associated with pancreatitis

A new protein was purified from the pancreatic juice of rats with acute pancreatitis. That protein, not detectable in control animals, was called "pancreatitis-associated protein." It was first observed 6 hours after induction of experimental pancreatitis with taurocholate or cerulein, reached maximal levels of 45 micrograms/mg protein in zymogen granules and 1.8 micrograms/mg protein in pancreatic tissue during the acute phase (48 hours), and disappeared during recovery (day 5). It was never detected in spleen, liver, kidney, heart, or lung. The detection limit of the assay system was 12 ng/mg protein, so that pancreatitis-associated protein levels increased at least 100-fold in pancreatic tissue during the acute phase. The molecular weight (12,000) and isoelectric point (8.2) were determined by two-dimensional gel electrophoresis. Subcellular fractionation and immunoelectron microscopy showed that the protein was synthesized on the rough endoplasmic reticulum and stored in zymogen granules before being secreted, similar to other pancreatic secretory proteins. Immunoblotting and two-dimensional gel electrophoresis revealed that the same protein was synthesized upon induction of pancreatitis by cerulein infusion, by retrograde injection of bile acids, or pancreatitis induced by pancreatic surgery. The pancreatitis-associated protein is therefore an acute-phase protein that differs from other proteins of that family because of its exocrine nature.

Splenic and gastro-duodenal vein occlusion—influence on the pancreatic gland and on the outcome of experimental pancreatitis

The observation that splenic vein thrombosis results in pancreatic changes similar to haemorrhagic pancreatitis initiated the present investigation. The influence of splenic and/or gastroduodenal vein occlusion on the pancreatic gland was evaluated and compared to that obtained after induction of experimental pancreatitis (EP). The influence of splenic vein occlusion on EP was also investigated. An approximately 4-fold increase in serum amylase activity was obtained after simultaneous ligation of the splenic and gastroduodenal veins. This increase was comparable to that obtained after EP. On the other hand, amylase activity in ascites was considerably lower after vein occlusion than after EP. Splenic vein occlusion in rats with EP more moderately increased the amylase activity but did not influence mortality rate 24 h postoperatively. Venous thromboses were observed in all groups with occluded veins but not in rats with EP. Vein occlusion alone did not result in fat necroses. Although occlusion of the splenic and gastroduodenal veins results in macromorphologic and biochemical changes resembling those in EP, the microscopic findings of the two conditions differ. Thus, the results do not support the hypothesis that pancreatic vein thromboses are of etiologic significance for the development of acute haemorrhagic pancreatitis.

Canine left ventricular function during experimental pancreatitis

Left ventricular contractility following induction of experimental pancreatitis (EP) was studied. Contractility was evaluated by analyzing the left ventricular end systolic pressure-diameter relationship ( Σ ES). Σ ES is independent of large changes in preload, afterload, and heart rate, but sensitive to changes in ventricular contractility. Following injection of 100,000 IU trypsin in 4% taurocholate into the pancreas to induce EP, seven of eight dogs survived 5 hr. These dogs exhibited an initial significant reduction in mean arterial pressure (MABP) which stabilized at 90% of control at 3–5 hr post-EP. Cardiac output (CO) dropped slowly after EP induction (from 3.08 ± 0.43 to 2.22 ± 0.22 liters/min) associated with no significant change in peripheral resistance. Stroke work and stroke volume were markedly depressed reflecting the changes in MABP and CO. No consistent changes in + dP/dt or − dP/dt were observed. The ratio of endo/epicardial blood flow was unchanged as was blood Ca 2+ levels throughout the experiment. Ventricular contractility as reflected by Σ ES tended to improve (from 49.7 to 69.6 mm Hg/mm at 4 hr following EP). Therefore, it was concluded that these animals exhibited no loss of ventricular contractility during EP.

Pancreatic Secretory Proteins in Sera from Rats before and after Induction of Experimental Pancreatitis

This study has traced the behavior of rat anionic trypsin-like immunoreactivity and pancreatic secretory trypsin inhibitor (PSTI) immunoreactivity in the serum of rats undergoing bile-pancreatic duct infusions of buffered solutions with and without the addition of the bile salt taurocholate. Enzymatic analysis of alpha-amylase was also done. A mild pancreatic inflammation followed infusion of buffer alone, as determined by gross inspection of the pancreas and the behavior of serum levels of the above proteins. Animals infused with buffer and 4% taurocholate had major inflammatory changes, including gross hemorrhage into the gland, and marked elevations in serum levels of the three proteins studied. Graphic analysis of the serum levels revealed distinct sharp rises in the serum levels of all three proteins in the taurocholate group. In the buffered saline group only an initial sharp rise was present, followed by a prolonged decrease back towards base-line values. The immunoreactive trypsin in the taurocholate group was present in three fractions with different molecular weights: trypsin in complex with protease inhibitors, trypsinogen, and trypsinogen, and degradation products. PSTI immunoreactivity showed the molecular size of free inhibitor and that of degradation products. The presence of trypsin in complex with protease inhibitors indicates the formation of active trypsin during acute pancreatitis, which is further supported by the presence of degradation products of trypsin and PSTI.

Alcohol and Acute Pancreatitis

The effect of chronic alcohol pretreatment and various pancreatobiliary secretions on the severity of experimental pancreatitis was studied in the rat. 95 rats were pretreated with ethanol (20% w/v, 1.1 ml/100 g body weight) five times weekly for 10 to 12 weeks by gastric intubation. 88 rats served as controls. Pancreatic lesions were produced by retograde injection of different pancreatobiliary secretions into the pancreatic ducts. The secretions were collected from both normal and chronically alcohol-fed rats, and each was used for induction of experimental pancreatitis in the control and alcohol pretreated rats. Bile obtained from normal rats was no more toxic to the pancreas than 0.9% saline solution, while bile obtained from the chronically alcohol-fed rats caused significantly more serious lesions to the pancreas than did normal rat bile. Bile-pancreatic juice (mixture of secretions at papilla of Vater) of normal and chronically alcohol-fed rats was as toxic as the bile of the alcohol-fed rats. Alcohol pretreatment had no significant effect on the severity of pancreatitis when control and alcohol-fed groups separately or the whole material according to pretreatment was examined. These results suggest that the metabolic effects of ethanol on the pancreas as such do not sensitize the pancreas to acute pancreatitis. An exogenous mechanism is required. The reflux of toxic alcoholic bile into the pancreas might act as an induction factor in acute alcohol pancreatitis.

Influence of acute pancreatitis on central hemodynamic, regional blood flow distribution and arteriovenous shunting in the dog.

Circulatory dearrangement during acute pancreatitis has been studied with the aid of differently sized (15 and 50 <i>µ</i>m) and labelled microspheres, intracardially infused before and 7 h after induction of experimental pancreatitis. A drop of arterial pressure (–26%), cardiac output (–65%) and left ventricular work (–87%) was registered together with a rise of resistance in systemic (+87%) and pulmonary (+188%) vessels. The fractions of cardiac output were increased to the heart (+64%), brain (+51%), liver (+194%), stomach (+112%), small intestine (+49%) and pancreas (+37%). Systemic arteriovenous shunting of small compared to large microspheres to the lung was markedly reduced and there was no shunting through the preportal area. The circulatory dearrangement was similar to that of a 30% acute blood volume withdrawal, and might be explained by the extensive plasma loss (–45%).