Morphologic effects of ethionine on the pancreas of the Chinese hamster. A light and electron microscopic study of degenerative changes

Animal models of gastrointestinal and liver diseases. Animal models of acute and chronic pancreatitis

Animal models of pancreatitis are useful for elucidating the pathogenesis of pancreatitis and developing and testing novel interventions. In this review, we aim to summarize the most commonly used animal models, overview their pathophysiology, and discuss their strengths and limitations. We will also briefly describe common animal study procedures and refer readers to more detailed protocols in the literature. Although animal models include pigs, dogs, opossums, and other animals, we will mainly focus on rodent models because of their popularity. Autoimmune pancreatitis and genetically engineered animal models will be reviewed elsewhere.

Investigation of protective effect of L-carnitine on L-asparaginase-induced acute pancreatic injury in male Balb/c mice

INTRODUCTION

The present analysis deals with the biochemical and histopathological effects of L-carnitine in mice with L-asparaginase (ASNase)-induced experimental acute pancreatic injury (API).

METHODS

A total of 32 male Balb/c mice were divided into four groups as follows. Group I (control) was injected with single saline via the intraperitoneal route. Group II received 500 mg/kg of L-carnitine daily with the injected volume of 62.5-75 μl for 25-30 g mice using a Hamilton microinjector applied for 5 days. Group III received a single 10,000 IU Escherichia coli ASNase/kg body weight dose of ASNase at a dose of 500 mg/kg. Group IV received 500 mg/kg of L-carnitine daily and a single dose of 500 mg/kg of ASNase and were decapitated on the fifth day following the injection. Blood and pancreatic tissue samples were obtained for evaluation of histopathological structure and levels of malondialdehyde (MDA), reduced glutathione (GSH), total sialic acid (TSA), glucose, amylase and triglyceride.

RESULTS

In group III, compared to group IV and group I it was determined that levels of GSH and amylase were significantly lower while levels of MDA, TSA, glucose and triglyceride were higher. Levels of GSH, MDA, TSA, glucose, triglyceride and amylase, especially in group IV, approached that of group I. As a result, L-carnitine for ASNase-induced API mice may be protective against pancreatic tissue degeneration and oxidative stress or lipid peroxidation.

Octreotide prevents L-asparaginase-induced pancreatic injury in rats

OBJECTIVE

L-asparaginase (ASNase) is one of the most effective chemotherapeutic means for inducing remission in acute lymphoblastic leukemia. However, because of unknown risk factors, severe pancreatitis sometimes occurs in patients receiving ASNase. We assessed the effect of ASNase on pancreatic acinar cells and then investigated the preventive effects of octreotide against ASNase-induced pancreatic injury in rats.

MATERIALS AND METHODS

Rats received intraperitoneal injections of an Escherichia coli ASNase solution (200, 500, or 1000 IU/kg) or normal saline as a control every 24 hours for 5 days. Octreotide (3 microg/kg) was injected subcutaneously with ASNase (1000 IU/kg) every 8 hours for 5 days. Rats were sacrificed 24 hours after the last injection of ASNase or normal saline.

RESULTS

Only the rats given 1000 IU/kg ASNase had significantly increased levels of pancreatic amylase (1962 +/- 152 vs 2179 +/- 84 IU/L, p < 0.01), trypsin (27.3 +/- 3.6 vs 41.1 +/- 22.8 IU/L, p < 0.05), and pancreatic secretory trypsin inhibitor (0.03 +/- 0.09 vs 0.27 +/- 0.10 ng/mL, p < 0.01) as compared to the control group. In addition, the acinar cells showed histological damage; however, octreotide injection provided protection against histological damage and the pancreatic enzymes remained within normal limits.

CONCLUSIONS

Although ASNase by itself did not cause pancreatitis, it did cause increased levels of pancreatic enzymes and histological damage to the pancreas associated with pancreatic injury or pre-pancreatitis. Prior treatment with octreotide prevented the development of ASNase-induced pancreatic injury.

Acute pancreatitis: animal models and recent advances in basic research

Acute pancreatitis (AP) is characterized by edema, acinar cell necrosis, hemorrhage, and severe inflammation of the pancreas. Patients with AP present with elevated blood and urine levels of pancreatic digestive enzymes, such as amylase and lipase. Severe AP may lead to systemic inflammatory response syndrome and multiorgan dysfunction syndrome, which account for the high mortality rate of AP. Although most (>80%) cases of AP are associated with gallstones and alcoholism, some are idiopathic. Although the pathogenesis of AP has not yet been elucidated, a common feature is the premature activation of trypsinogen within pancreatic tissues, which triggers autodigestion of the gland. Recent advances in basic research suggest that etiologic factors including cyclooxygenase-2, substance P, and angiotensin II may have novel roles in this disease. Basic research data obtained thus far have been based on animal models of AP ranging from mild edematous pancreatitis to severe necrotizing pancreatitis. In view of this, an adequate selection of experimental animal models is of paramount importance. Notwithstanding these animal models, it should be emphasized that none of these models mimic the clinical situation where varying degrees of severity usually occur. In this review, commonly used animal models of AP will be critically evaluated. A discussion of recent advances in our knowledge about AP risk factors is also included.

Dose-dependent effect of continuous subcutaneous verapamil infusion on experimental acute pancreatitis in mice

Calcium antagonists may limit experimental tissue injury by membrane stabilization. We studied the effects of verapamil on pancreatic ultrastructure and zymogen extraction during diet-induced acute pancreatitis. Acute pancreatitis was induced in female Swiss-Webster mice by feeding a choline- and methionine-deficient diet (CD) supplemented with 1% ethionine (CDE). Varying doses of verapamil in normal saline were infused continuously at a rate of 0.5 microliter/hr for 96 hr through subcutaneously implanted osmotic pumps. The pancreata were examined blindly by light microscopy and by electron microscopy. Zymogen extracted from pancreatic tissue was measured and expressed per gram of protein. Mean histological scores, calculated according to a formula that incorporates the extent of necrosis, inflammation, acidophilia, and edema, were 14.1 +/- 4, 10.3 +/- 2, 9.9 +/- 4, 5.9 +/- 7, 12.5 +/- 4, and 12.7 +/- 4 for CDE-fed animals receiving 0, 0.14, 0.28, 0.56, 0.84, and 1.12 microM verapamil daily, respectively. Animals fed normal diet or CD had scores of 0 +/- 0. Histological scores were significantly lower in animals treated with 0.56 microns verapamil compared to animals who received no verapamil (p < 0.05) and was associated with reduced dissolution of the zymogen granule membrane on EM. Mean extracted trypsinogen and chymotrypsinogen content were reduced in the CD- and CDE-fed mice. The reduction in mean trypsinogen content reached statistical significance in CDE-fed mice treated with verapamil 0.56 microM daily. Mean chymotrypsinogen content was also significantly reduced CD-mice and in mice treated with 0.56 microns and 0.84 microM of verapamil daily. Increasing doses of verapamil protect against diet-induced pancreatitis in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of the cholecystokinin receptor antagonist L-364,718 on pancreatitis induced by a deficient in choline and supplemented with ethionine (CDE) diet in the rat

The role of cholecystokinin (CCK) in the development of a necrotizing acute pancreatitis induced by a diet deficient in choline and supplemented with ethionine (CDE) has been evaluated in the rat by using a potent CCK receptor antagonist L-364,718. Acute pancreatitis was induced by administration of CDE diet for 14 days. L-364,718 administration was carried out by subcutaneous injections at dose of 0.1 mg/kg/day. Pancreatic exocrine secretion (flow, protein, amylase and trypsin outputs) in resting and under infusion of 1.25 microgram/kg/h of CCK-8 were used to evaluate the pancreatic functionality. Others parameters (serum amylase, percentage fluid in pancreas, haematocrit and mortality) evaluated the severity of pancreatitis. L-364,718 slightly reduced the mortality and the increases of percentage of fluid accumulated in pancreas in CDE diet acute pancreatitis. Basal and CCK stimulated pancreatic secretion was significantly depressed 36 hours after L-364,718 treatment. A slight response to CCK was observed. Nevertheless it was lower than usually observed in control rats. Our results demonstrate that in the rat, chronic L-364,718 treatment did not completely restore pancreatic activity in acute pancreatitis induced by CDE diet. Hence CCK cannot be considered as the main factor involved in the development of this pancreatitis model.

4-Hyroxyaminoquinoline-1-oxide-induced ultrastructural changes in the guinea-pig exocrine pancreas

4-hydroxyaminoquinoline, a carcinogen was injected into guinea-pigs intravenously in a single dose of 22-5 mg/kg. The sequential morphological changes in the exocrine cells of the pancreas were studied by electron microscopy at selected intervals between 18 and 60 hr. The earliest alterations in the acinar cells comprised nucleolar segregation into granular and fibrillar components and minimal dilatation of endoplasmic reticulum. At later intervals all the cytoplasmic organelles appeared altered. The endoplasmic reticular channels were markedly dilated with depletion of membrane bound and free ribosomes. The mitochondria were swollen and irregular with disruption of limiting membranes and cristae. The zymogen granules were markedly reduced or completely absent. The hyaloplasm contained morphologically variable cytoplasmic degenerative bodies. In addition to the acinar cells, centriacinar and ductal epithelial cells showed similar changes.