A comparison of alcoholic pancreatitis in rat and man

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.

Alcohol and high fat induced chronic pancreatitis: TRPV4 antagonist reduces hypersensitivity

The pathogenesis of pain in chronic pancreatitis is poorly understood, and its treatment can be a major clinical challenge. Surgical and other invasive methods have variable outcomes that can be unsatisfactory. Therefore, there is a great need for further discovery of the pathogenesis of pancreatitis pain and new therapeutic targets. Human and animal studies indicate a critical role for oxidative stress and activation of transient receptor potential (TRP) cation channel subfamily members TRPV1 and TRPA1 on pancreatic nociceptors in sensitization mechanisms that result in pain. However, the in vivo role of transient receptor potential cation channel subfamily V member 4 (TRPV4) in chronic pancreatitis needs further evaluation. The present study characterized a rat alcohol/high fat diet (AHF)-induced chronic pancreatitis model with hypersensitivity, fibrotic pathology, and fat vacuolization consistent with the clinical syndrome. The rats with AHF-induced pancreatitis develop referred visceral pain-like behaviors, i.e. decreased hindpaw mechanical thresholds and shortened abdominal and hindpaw withdrawal latency to heat. In this study, oxidative stress was characterized as well as the role of TRPV4 in chronic visceral hypersensitivity. Lipid peroxidase and oxidative stress were indicated by increased plasma thiobarbituric acid reactive substances (TBARS) and diminished pancreatic manganese superoxide dismutase (MnSOD). The secondary sensitization associated with AHF-induced pancreatitis was effectively alleviated by the TRPV4 antagonist, HC 067047. Similarity of the results to those with the peripherally restricted μ-opiate receptor agonist, loperamide, suggested TRPV4 channel activated peripheral sensitization. This study using a reliable model that provides pre-clinical correlates of human chronic pancreatitis provides further evidence that TRPV4 channel is a potential therapeutic target for treatment of pancreatitis pain.

Pharmacological attenuation of chronic alcoholic pancreatitis induced hypersensitivity in rats

AIM

To characterize an alcohol and high fat diet induced chronic pancreatitis rat model that mimics poor human dietary choices.

METHODS

Experimental rats were fed a modified Lieber-DeCarli alcohol (6%) and high-fat (65%) diet (AHF) for 10 wk while control animals received a regular rodent chow diet. Weekly behavioral tests determined mechanical and heat sensitivity. In week 10 a fasting glucose tolerance test was performed, measuring blood glucose levels before and after a 2 g/kg bodyweight intraperitoneal (i.p.) injection of glucose. Post mortem histological analysis was performed by staining pancreas and liver tissue sections with hematoxylin and eosin. Pancreas sections were also stained with Sirius red and fast green to quantify collagen content. Insulin-expressing cells were identified immunohistochemically in separate sections. Tissue staining density was quantified using Image J software. After mechanical and heat sensitivity became stable (weeks 6-10) in the AHF-fed animals, three different drugs were tested for their efficacy in attenuating pancreatitis associated hypersensitivity: a Group II metabotropic glutamate receptor specific agonist (2R,4R)-4-Aminopyrrolidine-2,4-dicarboxylate (APDC, 3 mg/kg, ip; Tocris, Bristol, United Kingdom), nociceptin (20, 60, 200 nmol/kg, ip; Tocris), and morphine sulfate (3 mg/kg, μ-opioid receptor agonist; Baxter Healthcare, Deerfield, IL, United States).

RESULTS

Histological analysis of pancreas and liver determined that unlike control rats, AHF fed animals had pancreatic fibrosis, acinar and beta cell atrophy, with steatosis in both organs. Fat vacuolization was significantly increased in AHF fed rats (6.4% ± 1.1% in controls vs 23.8% ± 4.2%, P < 0.05). Rats fed the AHF diet had reduced fasting glucose tolerance in week 10 when peak blood glucose levels reached significantly higher concentrations than controls (127.4 ± 9.2 mg/dL in controls vs 161.0 ± 8.6 mg/dL, P < 0.05). This concurred with a 3.5 fold higher incidence of single and small 2-10 cell insulin-positive cell clusters (P < 0.05). Insulin expressing islet of Langerhans cells appeared hypertrophied while islet number and area measurements were not different from controls. Weekly behavioral tests determined that mechanical and heat sensitivities were significantly increased by 4 wk on AHF diet compared to controls. Hypersensitivity was attenuated with efficacy similar to morphine with single dose treatment of either metabotropic glutamate receptor 2/3 agonist APDC, or nociceptin, the endogenous ligand for opioid-receptor-like 1 receptor.

CONCLUSION

The AHF diet induces a chronic alcoholic pancreatitis in rats with measurable features resembling clinical patients with chronic pancreatitis and type 3c diabetes mellitus.

Acute alcohol-induced pancreatic injury is similar with intravenous and intragastric routes of alcohol administration

OBJECTIVES

Five percent of alcoholics develop an acute pancreatitis (AP). The mechanism leading to pancreatic injury is not yet understood. Microcirculatory disorders seem to play a pivotal role. The objective of this study was to compare alcoholic pancreatic injury in response to intravenous and intragastric routes of alcohol administration.

METHODS

Alcohol was applied in rats intravenously (IV) or gastric via a surgical implanted feeding tube (IG). Serum alcohol concentration was maintained between 1.5‰ and 2.5‰. Four subgroups (n = 6/group) were examined in the IV/IG arm and compared with healthy controls. Pancreatic microcirculation, enzyme levels, and morphological damage were assessed after 3, 6, 12, and 24 hours.

RESULTS

Microcirculatory analysis showed significantly disturbed pancreatic perfusion and increased adherent leukocytes in IV and IG animals. In IV and IG groups, serum amylase was increased without morphological signs of AP compared with healthy controls.

CONCLUSIONS

Alcohol application does not induce AP in rodents, but impairs pancreatic microcirculation irrespectively of the application route. Intravenous application is commonly used and shows no disadvantages compared with the physiological intragastric application form. Therefore, the intravenous route offers a valid model, which mimics the physiological process for further studies of the influence of acute alcohol intoxication on the pancreas.

Animal models of pancreatitis: Can it be translated to human pain study?

Chronic pancreatitis affects many individuals around the world, and the study of the underlying mechanisms leading to better treatment possibilities are important tasks. Therefore, animal models are needed to illustrate the basic study of pancreatitis. Recently, animal models of acute and chronic pancreatitis have been thoroughly reviewed, but few reviews address the important aspect on the translation of animal studies to human studies. It is well known that pancreatitis is associated with epigastric pain, but the understanding regarding to mechanisms and appropriate treatment of this pain is still unclear. Using animal models to study pancreatitis associated visceral pain is difficult, however, these types of models are a unique way to reveal the mechanisms behind pancreatitis associated visceral pain. In this review, the animal models of acute, chronic and un-common pancreatitis are briefly outlined and animal models related to pancreatitis associated visceral pain are also addressed.

Animal models for investigating chronic pancreatitis

Chronic pancreatitis is defined as a continuous or recurrent inflammatory disease of the pancreas characterized by progressive and irreversible morphological changes. It typically causes pain and permanent impairment of pancreatic function. In chronic pancreatitis areas of focal necrosis are followed by perilobular and intralobular fibrosis of the parenchyma, by stone formation in the pancreatic duct, calcifications in the parenchyma as well as the formation of pseudocysts. Late in the course of the disease a progressive loss of endocrine and exocrine function occurs. Despite advances in understanding the pathogenesis no causal treatment for chronic pancreatitis is presently available. Thus, there is a need for well characterized animal models for further investigations that allow translation to the human situation. This review summarizes existing experimental models and distinguishes them according to the type of pathological stimulus used for induction of pancreatitis. There is a special focus on pancreatic duct ligation, repetitive overstimulation with caerulein and chronic alcohol feeding. Secondly, attention is drawn to genetic models that have recently been generated and which mimic features of chronic pancreatitis in man. Each technique will be supplemented with data on the pathophysiological background of the model and their limitations will be discussed.

Transient stasis of pancreatic fluid flow together with mild injury of the pancreatic duct cause chronic pancreatitis

BACKGROUND

Little is known about the etiopathogenesis of chronic pancreatitis, due mainly to the lack of simple animal models suitable to study inflammatory and fibrogenetic processes in the pancreas.

AIMS

The purpose of this study was to examine whether transient congestion of pancreatic fluid flow alone or slight ductal injury alone is sufficient, or where both are required, to induce chronic pancreatic injury.

METHODS

Three different models of pancreatitis were tested in rats induced by retrograde intraductal infusion of 40 μl/100 g body weight of 0.01% agarose (group A), 40 μl/100 g body weight of 0.1% sodium taurocholate (group T), or a mixture of the two solutions (group M). Histological alterations of the pancreas were examined by hematoxylin-eosin staining, changes in type IV collagen structure were studied by immunostaining, and the gelatinolytic activity of latent and active matrix metalloproteinase-2 (MMP-2) was analyzed by zymography.

RESULTS

In group A and T rats, histological alterations of the pancreas and the gelatinolytic activity of MMP-2 returned to baseline levels by day 14, and immunoreactivity for type IV collagen appeared as continuous lines along the basement membrane. In group M rats, however, acinar damage, fibrosis and fatty degeneration were observed even on day 56, and type IV collagen was detected as discontinuous lines until day 56. MMP-2 was significantly elevated from day 5 to day 42.

CONCLUSIONS

Co-existence of transient stasis of pancreatic fluid flow, together with mild damage to the pancreatic duct and acinar cells, exert synergistic effects on the development of persistent pancreatic injury with continuous disorganization of type IV collagen in the basement membrane of the ducts.

Risk factors for sporadic pancreatic endocrine tumors: a case-control study of prospectively evaluated patients

OBJECTIVES

Pancreatic endocrine tumors (PETs) are heterogeneous tumors with increasing prevalence. Little is known about the molecular pathogenesis and risk factors for the occurrence of sporadic PETs. The aim of this study was to identify the risk factors associated with the occurrence of sporadic PETs.

METHODS

A case-control study comprising 162 sporadic PETs and 648 controls was undertaken. Subjects were interviewed using a specific questionnaire on demographics and potential risk factors, including smoking, alcohol, height, weight, medical history, and family history of cancer. A multiple hierarchical logistic regression analysis was performed with a stepwise variable- selection procedure.

RESULTS

A first-degree family history of any cancer was a significant risk factor (odds ratio (OR) 2.2; 95% confidence interval (CI): 1.5-3.2). Among the different cancer sites, first-degree family history of pancreatic adenocarcinoma was more frequent in PETs than in controls (4.3 vs. 1.2%; P=0.01). A high alcohol intake (OR 4.8; 95% CI: 2.4-9.5), history of chronic pancreatitis (CP) (OR 8.6; 95% CI: 1.4-51), and recent-onset diabetes (OR 40.1; 95% CI: 4.8-328.9) were all independent risk factors. The history of diabetes was also associated with metastatic disease at the time of diagnosis.

CONCLUSIONS

This case-control study identified family history of any cancer (and to a less extent of pancreatic adenocarcinoma), CP, high alcohol intake, and recent-onset diabetes as risk factors for PET, thus suggesting a possible partial overlap with risk factors for exocrine pancreatic carcinogenesis.

A new model of chronic pancreatitis in rats

This study was designed to examine whether continuous pancreatic ductal hypertension (PDH) plays an important role in the onset and development of chronic pancreatitis (CP). Pancreatic, biliary, and duodenal cannulas were implanted in male Wistar rats. PDH was induced by vertically raising the free end of the pancreatic duct cannula to exert a hydrostatic pressure and maintained for 2 wk. PDH was gradually increased, but when the pancreatic juice (PJ) flow was interrupted, PDH was decreased to restore PJ flow. The induction of PDH resulted in a marked reduction of amylase activity in PJ and an increase in serum amylase activity. At 2 wk after persistent PDH, pancreatic exocrine function was markedly decreased in response to a bolus injection of secretin (100 pmol/kg) compared with the control group. Histological examination revealed interlobular as well as intralobular fibrosis in the form of nodular pancreatitis at 2 wk after the induction of PDH. Immunohistochemistry revealed the expression of fibronectin and collagen types I and III. Quantitative real-time RT-PCR showed an increase in transforming growth factor-beta(1) mRNA expression in the pancreas during PDH. The present results suggest that PDH plays an important role in the onset and development of CP. Furthermore, our animal model seems useful for investigating the mechanisms of CP in rats.

Rapid adaptation of pancreatic exocrine function to short-term alcohol feeding in rats

BACKGROUND

Chronic alcohol consumption increases the risk of pancreatitis in humans. Functional hyperstimulation/hypersecretion of the pancreas during chronic alcohol consumption appears to precede the onset of pancreatitis, and may contribute to the increased susceptibility to pancreatitis in alcoholics. However, the origin, nature and timing of hyperstimulation/hypersecretion are unknown.

METHODS

Male Wistar rats were pair-fed ethanol liquid diet for 15-18 days (including one 9-day dose ramp-up phase) or regular liquid diets before placement of pancreatic, biliary, duodenal and venous catheters. Basal and stimulated pancreatic secretions were measured with or without acute alcohol infusion. Pancreatic secretion was stimulated with intravenous bethanechol, 2-deoxy-D-glucose (2-DG), cholecystokinin (CCK), octapeptide (CCK-8), intraduodenal meal, or vehicle.

RESULTS

Acute alcohol potentiated 2-DG stimulated pancreatic secretion (184%, p < 0.05), whereas the response to CCK was unchanged, and the response to bethanechol was decreased (78%, p < 0.05). Short-term alcohol exposure lessened the exaggerated protein secretory response to 2-DG seen in acute alcohol exposure rats and increased the protein response to bethanechol (141%, p < 0.05), CCK (187%, p < 0.05) and meal (217%, p < 0.05).

CONCLUSION

The pancreas is sensitive to acute alcohol ingestion with inhibition of acinar cell function. Rapid adaptation occurs with short-term alcohol feeding, resulting in an exaggerated response to cholinergic input at the acinar cells, plus disinhibition of CCK and meal-stimulated pancreatic secretion. The central response to 2-DG and CCK are similar to area postrema lesions. Adaptation appears to be in response to alcohol-associated inhibition of the neurohormonal stimulatory pathway and compensatory upregulation at the acinar cell level.

Animal models and their results in gastrointestinal alcohol research

Alcohol-induced diseases of the gastrointestinal tract play an important role in clinical gastroenterology. However, the precise pathophysiological mechanisms are still largely unknown. Alcohol research depends essentially on animal models due to the fact that controlled experimental studies of ethanol-induced diseases in humans are unethical. Animal models have already been successfully applied to disclose and analyze molecular mechanisms in alcohol-induced diseases, partially by using knockout technology. Because of a lack of transferability of some animal models to the human condition, results have to be interpreted cautiously. For some alcohol-related diseases like chronic alcoholic pancreatitis, the ideal animal model does not yet exist. Here we provide an overview of the most commonly used animal models in gastrointestinal alcohol research. We will also briefly discuss the findings based on animal models as well as the current concepts of pathophysiological mechanisms involved in acute and chronic alcoholic damage of the esophagus, stomach, small and large intestine, pancreas and liver.

Alcoholic pancreatitis

Without doubt, alcohol consumption is one of the most important considerations in adults with acute or chronic pancreatitis. Understanding chronic pancreatitis as a complex disorder in which complimentary factors are required for recurrent acute and late chronic pancreatitis to develop in subsets of patients is critical for the early diagnosis and management of these individuals. Recent pathophysiological and genetic findings represent the beginning of major diagnostic and treatment breakthroughs that are likely to continue for the foreseeable future. The information provided in this article should provide the physician with a fresh perspective and remind the clinician of the importance of an accurate and complete history, and the need to document the actual alcohol consumption, pattern of drinking, and raise appropriate concerns if signs of alcoholism are detected. If alcohol-associated pancreatitis is detected, then limitation of pancreatic damage, limitation of progression, or preventative intervention should become the major concern.

Theories, mechanisms, and models of alcoholic chronic pancreatitis

Alcoholic chronic pancreatitis is a severe, disabling, chronic inflammatory condition of the pancreas that is seen in fewer than 5% of alcoholics. The severity and unpredictability of this condition has lead to several theories on the mechanism causing chronic pancreatitis based on careful clinical observation. Hypothetical mechanisms were applied to various animal models. Finally, following multiple lines of evidence, there is a convergence of thought and development of some new models that are quite instructive. Taken together, chronic alcohol consumption by rats results in multiple effects on the pancreas that increase the risk of acute pancreatitis, including ongoing acinar cell injury that lowers the threshold for hyperstimulation-induced acute pancreatitis, neurohormonal injury, and adaptation that results in acinar cell hyperstimulation, increased susceptibility to viral mediated acute pancreatitis, and possibly other factors. After acute pancreatitis initiates the inflammatory process, the chronic inflammation and fibrosis of alcoholic chronic pancreatitis are driven by diet, the acinar cell stress response to continued alcohol that may be potentiated by toxic alcohol metabolites, hypoxia, hyperstimulation, and partial duct obstruction; plus the effects of proinflammatory immunocytes and cytokines; and by stellate cell-mediated fibrosis driven by anti-inflammatory cytokines, alcohol, and alcohol metabolites. The factors determining which alcoholic will develop alcoholic chronic pancreatitis likely involve genetic factors, dietary factors, and susceptibility to pancreatic injury through several mechanisms ranging from trauma to gallstones to viruses.

Ethanol inhibits the motility of rabbit sphincter of Oddi in vitro

AIM: The role of the sphincter of Oddi (SO) in ethanol (ETOH)-induced pancreatitis is controversial. Our aim was to characterise the effect of ETOH on basal and stimulated SO motility.

METHODS: SOs removed from white rabbits were placed in an organ bath (Krebs solution, pH7.4, 37 °C). The effects of 2 mL/L, 4 mL/L, 6 mL/L and 8 mL/L of ETOH on the contractile responses of the sphincter were determined. SOs were stimulated with either 0.1 μmol/L carbachol, 1 μmol/L erythromycin or 0.1 μmol/L cholecystokinin (CCK).

RESULTS: ETOH at a dose of 4 mL/L significantly decreased the baseline contractile amplitude from 11.98 ± 0.05 mN to 11.19 ± 0.07 mN. However, no significant changes in the contractile frequency were observed. ETOH (0.6%) significantly decreased both the baseline amplitude and the frequency compared to the control group (10.50 ± 0.01 mN, 12.13 ± 0.10 mN and 3.53 ± 0.13 c/min, 5.5 ± 0.13 cycles(c)/min, respectively). Moreover, 0.8% of ETOH resulted in complete relaxation of the SO. Carbachol (0.1 μmol/L) or erythromycin (1 μmol/L) stimulated the baseline amplitudes (by 82% and 75%, respectively) and the contractile frequencies (by 150% and 106%, respectively). In the carbachol or erythromycin-stimulated groups 2-6 mL/L of ETOH significantly inhibited both the amplitude and the frequency. Interestingly, a 4-5 min administration of 6 mL/L ETOH suddenly and completely relaxed the SO. CCK (0.1 μmol/L) stimulated the baseline amplitude from 12.37 ± 0.05 mN to 27.40 ± 1.82 mN within 1.60 ± 0.24 min. After this peak, the amplitude decreased to 17.17 ± 0.22 mN and remained constant during the experiment. The frequency peaked at 12.8 ± 0.2 c/min, after which the constant frequency was 9.43 ± 0.24 c/min throughout the rest of the experiment. ETOH at a dose of 4 mL/L significantly decreased the amplitude from 16.13 ± 0.23 mN to 14.93 ± 0.19 mN. However, no significant changes in the contractile frequency were observed. ETOH at a dose of 6 mL/L inhibited both the amplitudes and the frequencies in the CCK-stimulated group, while 8 mL/L of ETOH completely relaxed the SO.

CONCLUSION: ETOH strongly inhibits the basal, carbachol, erythromycin, and CCK-stimulated rabbit SO motility. Therefore, it is possible that during alcohol-intake the relaxed SO opens the way for pancreatic fluid to flow out into the duodenum in rabbits. This relaxation of the SO may protect the pancreas against alcohol-induced damage.

Chronic alcohol-induced alterations in the pancreatic secretory control mechanisms

Chronic alcohol ingestion appears to increase susceptibility of the pancreas to pancreatitis through multiple mechanisms. The aim of the current study was to determine the effect of chronic low- and high-dose alcohol consumption on the neurohormonal control of the exocrine pancreas in rats. Male Wistar rats were fed Lieber DeCarli liquid control-, low-, and high-dose alcohol diets for 3 months. Pancreatic exocrine secretion was measured under basal and 2-deoxy-D-glucose (2-DG)-, CCK-, bethanechol-, or meal-stimulated conditions while on chronic alcohol diets and after 2-DG or CCK stimulation during alcohol withdrawal in awake rats. Chronic alcohol ingestion was associated with a dose-related inhibition of basal pancreatic protein secretion, which was reversed upon alcohol withdrawal. Low-dose alcohol feeding had no effect on bethanechol-stimulated pancreatic secretion but altered 2-DG-stimulated pancreatic secretion. In chronic high-dose alcohol rats, meal- and bethanechol-stimulated protein secretion was significantly potentiated during early and late phases. The response to CCK appeared to be disinhibited, whereas the response to 2-DG was uniformly blunted. Upon withdrawal of low-dose alcohol, the response to 2-DG was potentiated, whereas with the withdrawal of high-dose alcohol, the response to CCK was potentiated. Adaptation to chronic alcohol consumption differs depending on the alcohol dose. The most significant effects were seen after high-dose alcohol withdrawal, with apparent loss of central inhibitory regulation combined with exaggerated response at the acinar cell level. This combination of factors could increase susceptibility to acute alcoholic pancreatitis through a hyperstimulation mechanism.

Animal models in gastrointestinal alcohol research-a short appraisal of the different models and their results

Alcohol-related diseases of the gastrointestinal tract play an important role in clinical gastroenterology. However, the mechanisms and pathophysiology underlying the effects of ethanol on the organs of the digestive tract are not yet completely understood. Animal models represent an essential tool for investigating alcohol-related diseases because they give researchers the opportunity to use methods that cannot be used in humans, such as knockout technology. However, there is still a need for new animal models resembling the human condition, since for some alcohol-related diseases such as chronic alcoholic pancreatitis, the ideal animal model does not yet exist. In this chapter, we provide an overview of the most commonly used animal models in gastrointestinal alcohol research. We will also briefly discuss the current concepts of the pathophysiological mechanisms involved in acute and chronic alcoholic damage of the oesophagus, stomach, small and large intestine, pancreas and liver.

Animal models in alcoholic pancreatitis--what can we learn?

Although the majority of patients with chronic pancreatitis present a history of excessive alcohol consumption, the pathophysiology underlying chronic alcoholic pancreatitis remains poorly defined. Since experimental animal models represent helpful tools in understanding human disease, numerous laboratory studies have been designed to study the effects of alcohol on the pancreas. In the present article we summarize the existing animal models that have been used to investigate the effects of acute and chronic alcohol application on the development of morphological alterations and pancreatic injury. Despite considerable experimental effort, acute or chronic ethanol feeding alone failed to cause acute or chronic pancreatitis in animals. However, ethanol-feeding and the combination with other procedures has demonstrated several mechanisms that play a role in ethanol-induced pancreatic injury. Among these ethanol-induced alterations and mechanisms are the reduction of pancreatic blood-flow and microcirculation, damaging effects of ethanol metabolites, increased pancreatic acinar cell expression of digestive and lysosomal enzymes, increased glandular enzyme content, additional nutritional factors, pancreatic duct obstruction, and limitations of pancreatic regeneration. Although no satisfactory animal model for alcoholic pancreatitis has been developed, these animal models have provided insights in several factors that predispose the pancreas to development of pancreatic injury and contribute to alcoholic pancreatitis.

Pathogenesis of alcohol-induced chronic pancreatitis: facts, perceptions, and misperceptions

The pathogenesis of chronic pancreatitis secondary to chronic alcoholism is not fully understood. A major hurdle in the understanding of the pathogenesis is the inability to study early lesions of the pancreas and the sequential changes. Facts are few; observations are many. Each new hypothesis argues against all previous hypotheses; however, clinical chronic pancreatitis is initiated by one or more of the mechanisms. Good experimental models for alcoholic pancreatitis are not available, limiting the ability to study the pathogenesis. Additional studies on genetic markers and immunologic mechanisms might explain acinar cell injury, which seems to be the earliest lesion in most, if not all, types of chronic pancreatitis. Opie's common channel and obstruction regurgitation theories seem unrelated to chronic pancreatitis. Although biochemical changes of the pancreatic secretion in alcoholic patients promote protein-plug formation, evidence is too weak to consider protein plug as the earliest change. The theory of necrosis of the acinar cell by some unknown mechanism, subsequently leading to fibrosis, is gaining support; however, it is clear that the pathogenesis of alcoholic pancreatitis is not yet fully understood.

Repetitive self-limited acute pancreatitis induces pancreatic fibrogenesis in the mouse

The role of repetitive acute injury in the pathogenesis of chronic pancreatitis remains unknown. To determine if repetitive injury induced by pancreatic hyperstimulation would reproduce the characteristic features of human chronic pancreatitis, acute reversible pancreatic injury was induced in mice by twice weekly cerulein treatment, 50 microg/kg/hr x 6 hr, for 10 weeks. Procollagen alpha1(I) mRNA was markedly increased by week 2. Sirius red staining of interstitial collagen demonstrated progressive accumulation of extracellular matrix surrounding acinar units and in interlobular spaces. Atrophy, transdifferentiation of acinar units to ductlike tubular complexes, and dilatation of intraacinar lumina also developed. Electron microscopy demonstrated the presence of stromal cells in areas of fibrosis with morphologic characteristics of pancreatic stellate cells. These findings demonstrate that, in a murine model, repetitive acute injury to the pancreas by hyperstimulation can reproduce the major morphological characteristics of human chronic pancreatitis.

The hydrolysis of fatty acid ethyl esters in low-density lipoproteins by red blood cells, white blood cells and platelets

Fatty acid ethyl esters (FAEE), esterification products of fatty acids and ethanol, have been implicated as toxic mediators of ethanol ingestion. In this study, we investigated the in vitro hydrolysis of FAEE reconstituted in low-density lipoproteins (LDL) when incubated with human blood, cell free plasma, red blood cells, white blood cells, and platelets. We also determined the metabolic fate of the fatty acid originally incorporated in the FAEE following FAEE hydrolysis. When FAEE were incubated with human red blood cells. white blood cells, or platelets, at physiologic cell counts, 80% of the FAEE were hydrolyzed at 2 h. The FAEE-derived fatty acid was predominantly found in phospholipid and free fatty acid fractions. Cell free plasma contained minimal FAEE hydrolytic activity. These studies demonstrate that FAEE are degraded to free fatty acids and ethanol by the cellular elements in the blood. The generation of free fatty acids from extensive hydrolysis of FAEE adds support to the growing concept that at least some of the toxic effects of FAEE are mediated by the free fatty acids generated upon hydrolysis of the ethyl esters.

Fatty acid ethyl and methyl ester synthases, and fatty acid anilide synthase in HepG2 and AR42J cells: interrelationships and inhibition by tri-o-tolyl phosphate

Synthesis of fatty acid ethyl esters (FAEEs), fatty acid methyl esters (FAMEs), and fatty acid anilides (FAAs) in humans and/or experimental animals and in vitro have been reported by us and other investigators. In previous studies, we have demonstrated that fatty acid ethyl ester synthase (FAEES), purified from rat liver microsomes, is structurally and functionally identical to the rat liver microsomal carboxylesterase (pI 6.1) and suggested a role in the conjugation of a variety of xenobiotic alcohols with endogenous fatty acids (B. S. Kaphalia, R. R. Fritz, and G. A. S. Ansari, Chem. Res. Toxicol. 11, 211-218, 1997). However, hepatic FAEES was found to be structurally and functionally different from that of pancreas. Therefore, the present study was undertaken to determine structural and functional interrelationships among the enzyme(s) involved in the synthesis of FAEEs, FAMEs, and FAAs, in HepG2 and AR42J cells using tri-o-tolyl phosphate (TOTP), a specific inhibitor for beta-esterases. Synthesis of FAEEs, FAMEs, and FAAs, studied in the HepG2 cells, was found to be dose- and time-dependent following incubation with methanol, ethanol, or aniline, respectively. Approximately 86-90% inhibition of FAEE, FAME, and FAA synthesizing activities was found in HepG2 cells following exposure to 2.5 microM TOTP. Identical profiles of dose- and time-dependent inhibition of FAEE, FAME, and FAA synthesizing activities by TOTP in HepG2 cells suggest that synthesis of FAEEs, FAMEs, and FAAs is catalyzed by the same enzyme(s). However, FAEE, FAME, and FAA synthesizing activities in AR42J cells could not be inhibited by TOTP under similar experimental conditions. A differential pattern of p-nitrophenyl acetate hydrolyzing activity (a measure of esterase activity) similar to that of fatty acid ester/anilide synthesizing activities was observed in the two cell lines. These results are further substantiated by the presence of approximately 60 kDa (subunit molecular weight) protein in the postnuclear fraction of HepG2 but not in AR42J cells by Western blot analysis using antibodies raised against FAEES, purified from rat liver microsomes or adipose tissue. Therefore, the enzyme responsible for the FAEE, FAME, or FAA synthesizing activities is most probably carboxylesterase in HepG2 cells and is structurally and functionally different than that present in AR42J cells. These studies also indicate the utility of HepG2 and AR42J cell cultures as an alternative to the animal model regarding studies on nonoxidative metabolism of alcohols and amines, in general.

Ethanol-mediated neutrophil extravasation in feline pancreas

Ethanol is a common cause of both acute and chronic pancreatitis. Studies in other organs suggest that polymorphonuclear neutrophils activated by ethanol may cause tissue injury in a variety of conditions. The aim of this study was to investigate the effects of ethanol on neutrophil extravasation in the feline pancreas. Pancreata were isolated and perfused at different flow rates with varying concentrations of ethanol in either a physiological or neutrophil depleted perfusate. Neutrophil extravasation was assessed by measuring pancreatic tissue myeloperoxidase (MPO) activity. Ethanol at 2.5% (54.25 mmol/liter) was the lowest concentration that still caused significant neutrophil extravasation (3.1+/-0.8 vs 1.9+/-0.2 units, P<0.05) and was accompanied by an increase in vascular resistance of 15%. Reduction of pancreatic perfusion by 15% did not significantly increase neutrophil extravasation. (1.1+/-0.3 vs 1.6+/-0.2 units, NS) Perfusion of the pancreas with neutrophil-depleted blood containing either ethanol or saline, followed by perfusion with an ethanol-free perfusate, showed an increase in neutrophil extravasation in the ethanol group compared to the control group (3.2+/-0.9 vs 1.9+/-0.2 units, P<0.05). In conclusion, ethanol causes neutrophil extravasation in the feline pancreas independent of blood flow changes and occurs despite the absence of direct neutrophil exposure to ethanol.

A review: acute and chronic effects of ethanol and alcoholic beverages on the pancreatic exocrine secretion in vivo and in vitro

Whereas oral or intraduodenal ethanol causes a moderate stimulation of pancreatic bicarbonate and enzyme output, intravenous ethanol inhibits basal and hormonally stimulated pancreatic exocrine secretion in humans, dogs, cats, pigs, rabbits, and rats. This inhibition could be mediated by inhibitory cholinergic mechanisms or be the result of a direct cellular effect of ethanol. In vitro investigations have specified several signaling molecules that may be involved in the action of ethanol on stimulus-secretion coupling in the exocrine pancreas, including cyclic adenosine monophosphate, intracellular calcium, and cholecystokinin and somatostatin receptors. In difference to pure ethanol solutions and distilled spirits, beer strongly stimulates pancreatic enzyme output, probably by nonalcoholic fermentation products. During chronic alcoholism, the ethanol-induced inhibition is replaced by an enhanced enzyme output that causes intraductal protein precipitation. In vitro investigations suggest that this increase is reversible after alcohol withdrawal. The occurrence of protein precipitates is considered to be a crucial step in the development of chronic alcoholic pancreatitis in humans. Other ethanol-induced secretory alterations that may contribute to the development of alcoholic pancreatitis are a decreased secretion of trypsin inhibitor, an increased cholinergic tone, and changes in the concentration of lithostathine.

The influence of ethanol on long-term effects of dibutyltin dichloride (DBTC) in pancreas and liver of rats

The present study was done to determine the additional influence of daily ethanol intake (15% in drinking water ad libitum) on long-term toxic effects of a single administration of dibutyltin dichloride (DBTC, 8 mg/kg b.w. i.v.) in pancreas and liver of rats. Pathohistological changes in pancreas, bile duct and liver as well as pathobiochemical parameters of pancreatitis (amylase and lipase activity), liver lesions (alkaline phosphatase activity and bilirubin) and fibrosis (hydroxyproline and hyaluronic acid) were measured 1 day and 1 to 24 weeks after DBTC- and DBTC/ethanol administration. DBTC alone induced in rats an acute interstitial pancreatitis as well as acute bile duct and liver lesions in the early experimental phase. Later on, the acute inflammatory processes in pancreas and liver took a chronic course resulting in pancreatic fibrosis and liver cirrhosis. Ethanol increased the toxic effects of DBTC on pancreas and liver during the acute and chronic course. In the acute phase lasting 1 day to 2 weeks, ethanol enhanced the DBTC toxicity on acinar cell and bilio-pancreatic duct epithelium as well as the formation of obstructive ductal plugs by necrotic cell debris. The obstruction and cholestasis in the DBTC/ethanol-group were significantly stronger as in the DBTC-group. The significant increase of hydroxyproline in urine and hyaluronic acid in serum of the DBTC/ethanol treated rats after 12 to 24 weeks was connected with a more severe chronic inflammatory fibrosis in pancreas and liver in comparison to the DBTC-treated group.

Do parotid duct abnormalities occur in patients with chronic alcoholic pancreatitis?

OBJECTIVE

Several studies have suggested that ethanol affects the pancreas and parotid gland. We performed a prospective study to determine whether ductal lesions of ethanol-induced chronic pancreatitis occur in the parotid.

METHODS

Parotid sialograms were performed in 11 alcoholic patients who had endoscopic retrograde pancreatograms. Sialograms and pancreatograms were examined in all subjects for ductal abnormalities.

RESULTS

Seven of nine patients (77.8%) with ductal lesions of the pancreas had coexistent ductal abnormalities of the parotid gland (Kendall's tau = 0.578, p = 0.035).

CONCLUSIONS

Chronic ethanol intake induces ductal alterations in the parotid gland similar to those seen in the pancreas. These results suggest a common histopathological effect of alcohol in the ductal system of the parotid gland and pancreas and raise the possibility that the parotid sialogram could be useful as an adjunct in the diagnosis of ethanol-induced chronic pancreatitis.

Effects of ethanol on the pancreas of disulfiram-treated rats

To study the effects of ethanol on disulfiram-treated rats, we administered ethanol orally at a does of 2000 mg/kg, twice daily for 5 days. The administration of ethanol or disulfiram alone produced no recognizable changes in pancreatic acinar cells. Ethanol administration, in disulfiram-treated rats resulted in a decrease in the content of zymogen granules in acinar cells, and the appearance of intraplasmic vacuolization. Electron microscopically, these vacuoles appeared on the basal side of nuclei. In addition, similar vacuoles appeared in liver cells, and these vacuolizations seemed to show lipid inclusions. However, ethanol administration to disulfiram-treated rats did not cause inflammatory changes or edema in the pancreas. A comparison of blood ethanol levels in rats receiving ethanol alone and disulfiram plus ethanol showed no significant difference, but acetaldehyde levels in rats receiving ethanol plus disulfiram rats were significantly higher than those in rats receiving ethanol alone. These findings suggested that acetaldehyde caused a decrease of zymogen granules and the presence of lipid inclusions in pancreatic acinar cells.

Pancreatic atrophy: a new model using serial intra-peritoneal injections of L-arginine

No simple rat model for chronic pancreatitis exists at present. A single dose of arginine has recently been shown to induce acute pancreatitis in rats. This study was designed to assess whether serial injections of arginine would induce reproducible chronic pancreatic damage. Forty rats received an intra-peritoneal injection of 500 mg per 100 g body weight of L-arginine followed by three injections of 250 mg per 100 g over 10 days. The rats were killed 24 h after each injection and at intervals of up to 6 months. Serum amylase levels were increased in the acute phase only. Examination of the pancreas at 24 h showed a severe oedematous pancreatitis. By day 5 there was up to 90% acinar destruction with adipose tissue replacement, although ductal, vascular, and islet cells appeared undamaged. These changes were present 6 months after injection. This is proposed as a new, simple, and reproducible method of inducing chronic pancreatic damage in the rat.

Dietary modulation of alcohol-induced pancreatic injury

This is a review of current progress in studies of alcohol-induced pancreatic injury using the rat intragastric ethanol infusion model. This model has been shown to reproduce the histopathologic characteristics of human ethanol-related pancreatic disease in a rodent model. A high fat liquid diet infused with ethanol potentiated the histologic and cellular effects of ethanol on the exocrine pancreas when compared to a low fat diet-ethanol infusion. Hypogranulation and apoptosis of pancreatic acinar cells are proposed as precursor lesions induced by ethanol leading to the subsequent development of acinar atrophy. A reduction in acinar cell sensitivity and responsiveness to cholecystokinin (CCK) is documented and proposed as a mechanism for the development of regressive changes through a reduction in the trophic effect of CCK.

Acute effects of ethanol and ethanol plus furosemide on pancreatic capillary blood flow in rats

The effects of intravenous ethanol and ethanol plus furosemide on pancreatic capillary blood flow (PCBF) were investigated using a laser-Doppler flowmeter. Forty Sprague-Dawley male rats were divided into 4 groups: (1) control, (2) 80% ethanol, (3) 80% ethanol plus furosemide, and (4) furosemide. Mean arterial blood pressure and heart rate were monitored. Levels of serum amylase, calcium, electrolytes, ethanol, and furosemide (groups 3 and 4) were measured, and samples of pancreatic tissue were obtained. The ethanol and furosemide levels were statistically different (p < 0.05). PCBF significantly decreased (p < 0.05) in group 2, increased (p < 0.05) in group 3, and did not differ (p > 0.05) between groups 1 and 4. Histopathologic analysis revealed swollen acini in group 2 and sparse focal necrosis without acinar swelling in group 3. The depressant effect of ethanol on PCBF may be the result of its direct action on pancreatic cells causing edema and capillary compression rather than on primary vascular control mechanisms that adjust blood flow. Furosemide counters this effect.

Effect of ethanol intake on pancreatic exocrine secretion in mice

Swiss mice were fed conventional lab chow and 10% ethanol or water as drinking fluid for 2 weeks. Pancreatic juice was obtained by cannulation of the bile pancreatic common duct of mice anesthetized with urethane. Isolated pancreatic lobules were also obtained. The flow rate and the amylase output were determined in pure pancreatic juice. The release of amylase was measured in pancreatic lobule preparations. The basal pancreatic juice flow rate and the amylase output were significantly increased by ethanol consumption. The magnitude of the pancreatic juice flow rate and the amylase output responses to increasing doses of bethanechol, a cholinergic agent, was significantly decreased in ethanol-fed mice. The amount of spontaneously released amylase was higher in pancreatic lobule preparations from ethanol-fed animals than that from control mice, and the difference was abolished by addition of atropine to the incubation media. The amylase release rate in response to increasing doses of bethanechol was significantly reduced in lobule preparations from the ethanol-fed group. These data indicate that ethanol intake in mice has a stimulating effect on the spontaneous pancreatic secretion and lends support to the hypothesis that ethanol consumption increases the intrapancreatic cholinergic tone.

Toxicology of the pancreas

The pancreas of mammals is capable of biotransforming drugs and other chemicals and subject to toxic injury by the resultant reactive metabolites. In the case of experimental animals, especially rodents, numerous chemical toxicants have been identified for the exocrine pancreas and, to a lesser degree, the endocrine component. These include alcohol, alloxan, azaserine, dimethylbenzo[a]anthracene, ethionine, 4-hydroxyaminoquinoline-1-oxide, beta-oxidized derivatives of dipropylnitrosamine, oleic acid, and streptozotocin. Depending on the toxicant, the cellular effects span the gamut from acute injury and death, to hyperplasia, metaplasia, and malignant transformation. In contrast to the well-established toxic effects of chronic alcohol abuse on the human pancreas, its susceptibility to toxic injury by therapeutic drugs has become clinically apparent more recently. A drug should be considered as toxic only when it induces acute pancreatitis documented by clinical findings and laboratory tests; the condition improves when the drug is discontinued and worsens when the patient is challenged by readministration of the drug. At present, only 8 therapeutic drugs have fulfilled these criteria and are classified as toxic for pancreas. These are, azathioprine, estrogens, furosemide, methyldopa, pentamidine, procainamide, sulfonamides, and thiazide diuretics. Controlled exposure to cultured component cells of pancreas may be of potential value in identifying such drugs, documenting their toxicity, and allowing for biochemical and toxicologic investigation of the mechanisms involved.

Alcohol-induced pancreatic injury (Part 2). Evolution of pathogenetic theories

In Part I of this paper, features of alcoholic pancreatitis that are still poorly understood were reviewed and factors that might favor biliary-pancreatic reflux were summarized. Part II deals with additional pathogenetic schemes that might shed light on this perplexing disorder.

Pressure of papillary sphincter zone and pancreatic main duct in patients with alcoholic and idiopathic chronic pancreatitis

To determine the significance of manometric pressure of the pancreatic duct in patients with alcoholic and idiopathic chronic pancreatitis, we used a microtransducer inserted through a duodenoscope to measure pressures in the papillary sphincter zone and pancreatic main duct in 20 control subjects and 31 patients with chronic pancreatitis without papillary stenosis including 10 cases of alcoholic chronic pancreatitis (ALCP) and 21 cases of idiopathic chronic pancreatitis (ICP). The pancreatic main ductal pressure was significantly higher in the patients with ALCP (55.7 +/- 28.9 mm Hg) or ICP (44.5 +/- 25.8 mm Hg) than in the controls (16.2 +/- 8.7 mm Hg), but there was no significant difference between ALCP and ICP. There was no significant difference between control subjects and ICP in the motility of the sphincter of Oddi. In ICP there were no correlationships between pancreatic ductal pressure and the motility of papillary sphincter zone. In ALCP, the frequency of the papillary sphincter waves was significantly higher than in normal subjects and there was a correlation between the pancreatic ductal pressure and the motility of the papillary sphincter zone. These data suggest that increased pancreatic ductal pressure in ALCP may be in part due to papillary dysfunction, but not in ICP.

Effect of long-term ethanol feeding on the restoration process of acute necrotizing pancreatitis induced in rats

This study was conducted to elucidate the possible influence of long-term peroral administration of alcohol on the repair process of acute necrotizing pancreatitis. Male Wistar rats fed with balanced diet were divided into two groups. The first group had free access to 15% ethanol, and the second group, the control group, has access to water instead. After fifty weeks, acute necrotizing pancreatitis was induced in rats by infusing 0.4% lysolecithin into their pancreatic duct. In the course of pancreatitis, pancreatic enzymes in serum, enzymes and protein in pancreas, and DNA synthesis in pancreas in both groups, changed in the same way. Histologically, interstitial edema, necrosis of parenchyma, infiltration of inflammatory cells, and formation of tubular complex were observed. Most of these histological changes of pancreas in both groups disappeared in twenty days and pancreas was repaired almost completely. These findings suggest that the repair process of acute necrotizing pancreatitis is not affected by preceding long-term intake of alcohol.

Potentiation of ethanol-induced pancreatic injury by dietary fat. Induction of chronic pancreatitis by alcohol in rats

Effects of sustained ethanol intoxication and dietary fat content on pancreatic morphology were investigated in the rat model implanted with gastrostomy catheters, which permitted continuous intragastric infusion of ethanol plus liquid diet containing one of three levels of corn oil: 5% (low-fat), 25% (high-fat), and 35% (extra-high-fat) of total calories. After various durations of infusion ranging from 30 to 160 days, the pancreatic histology was examined. Mean blood alcohol levels achieved in the low, high, and extra-high fat diet groups were similarly high: 210 +/- 120, 224 +/- 122, and 289 +/- 110 mg/dl. The average weight gain of these ethanol-fed groups during the first 8 weeks of experiments was 15.4 +/- 1.9, 19.6 +/- 8.0, and 14.9 +/- 5.2 g/wk, respectively, and was not statistically different from that of pair-fed controls infused with isocaloric amount of dextrose and respective diet, nor from that of age-matched animals given the regular chow. None of control animals showed abnormal pancreatic morphologic features except occasional mild steatosis in those fed the extra-high-fat diet. With the low dietary intake of unsaturated fat, chronic ethanol intoxication produced only mild pancreatic pathology such as steatosis and interstitial edema. Administration of ethanol and the high-fat and extra-high-fat diets caused hypogranulation and apoptosis of acinar cells. Focal lesions of chronic pancreatitis were also observed in 20% or 30% of ethanol-fed animals given the high-fat or extra-high-fat diet. These lesions were characterized by fat necrosis, mononuclear cell infiltration, fibrosis, acinar atrophy, ductal dilatation, and intraductal mucious or proteinacious plugs. The incidence of focal acute pancreatitis was less (7-20%) but appeared increased with higher dietary fat content. Induction of either acute or chronic pancreatitis was not correlated with plasma levels of triglycerides or cholesterol. These results demonstrate potentiation by dietary unsaturated fat of ethanol-induced pancreatic injury. This model possesses many features analogous to those seen in alcoholic pancreatic injury in man. The hyperlipidemia does not appear to be an important pathogenetic factor for ethanol-induced pancreatitis produced in this model.

Pancreatic atrophy follows bile-induced acute pancreatitis in the rat

The late course of bile-induced acute experimental pancreatitis was studied in alcoholic and non-alcoholic rats. Addition of alcohol to the drinking water did, however, not influence any of the factors (see below) studied. Six hours after induction of pancreatitis the animals displayed a sixfold increase of S-amylase levels. The late mortality in the whole group of animals was 19% after 6 weeks and 71% after 12 weeks. Rats surviving 6 weeks had a marked reduction of pancreatic wet weight and of pancreatic protein, amylase, phospholipase A2, and S-glucose as compared with healthy controls. S-amylase was similar in all groups studied after 6 weeks. At light microscopy similar changes were seen after 6 and 12 weeks--that is, extensive atrophy of the exocrine pancreas with preserved islets of Langerhans. Only slight fibrosis and slight increase of inflammatory cells were seen, and no protein plugs were detected. The normal liver architecture was generally preserved, but pancreatic rats showed various degrees of bile duct proliferation. Although the morphologic findings do not correspond well with those seen in human chronic pancreatitis, we feel that they represent an integrated late phenomenon of the bile-induced pancreatitis per se, even though partial obstruction of the bile-pancreatic duct may be a co-factor.

Possible mechanisms of acute pancreatitis induced by ethanol

We investigated the effect of intravenous and intragastric ethanol on pancreatic duct pressure, duct permeability to dextran molecules (20,000 molecular weight), and on the development of acute pancreatitis in an experimental model of the disease. Intragastric ethanol caused a small increase in pancreatic duct pressure (6 to 7 mm Hg) and an increase in duct permeability to dextran. Intravenous ethanol with exclusion of the sphincter of Oddi did not increase pancreatic duct pressure or permeability. Intravenous ethanol and intragastric normal saline solution altered neither pressure nor permeability. Artificial elevation of pancreatic duct pressure alone with no ethanol had no effect on duct permeability. However, when intravenous ethanol was given to produce similar systemic concentrations as achieved in the intragastric experiments (250 mg/dl) and duct pressure was artificially raised, duct permeability was increased. Ethanol concentrations similar to those found in peripheral blood were detected in secretin-stimulated pancreatic juice. Perfusion of the pancreatic duct with activated pancreatic enzymes after intragastric but not intravenous ethanol (that is, only in animals with increased duct permeability) caused acute edematous pancreatitis. Our results confirmed that increased duct permeability was necessary to produce acute pancreatitis in this model, and that this increase in permeability resulted from both a small increase in duct pressure and probably from the toxic metabolic effects of ethanol.

Effects of ethanol feeding on collagen synthesizing and degrading enzymes in rat pancreas

Collagen metabolism in the pancreas was investigated in male Wistar strain rats after 7 weeks of ethanol feeding. Compared with control rats, the ethanol-fed rats had a normal hydroxyproline content in the pancreas. However, prolyl hydroxylase activity and collagenolytic cathepsin activity were increased, though collagenase activity did not change. Both prolyl hydroxylase activity and collagenolytic cathepsin activity were inversely correlated with amylase activities. These findings were also confirmed in ethanol-pyrazole treated rats. These results suggest that the ethanol-induced pancreatic injury, even at an early stage, accelerates the collagen metabolism in the pancreas.

Alcoholic pancreatitis in rats fed ethanol in a nutritionally adequate liquid diet

In an effort to develop a model of chronic alcoholic pancreatitis in Sprague-Dawley rats fed a nutritionally adequate diet, 3 groups of 15 animals each were fed Wayne Rodent-Blox ad libitum, Lieber-DeCarli diet with 40% of carbohydrate calories replaced by ethanol ad libitum and isocaloric amounts of Lieber-DeCarli diet respectively for a period of 18 months. Rats were anesthetized and basal and secretin-stimulated pancreatic juice was obtained. Pancreatic glands were isolated and divided into portions for histology, biochemical analyses, and cell fractionation. The homogenate, zymogen granule fraction, mitochondrial-lysosomal fraction, microsomal fraction and postmicrosomal supernatant as well as aliquots of pancreatic juice were analyzed for cathepsin B, acid phosphatase, beta-D-glucoronidase, arylsulphatase and leucine naphthylamidase. All of the ethanol-fed animals developed morphological changes akin to human chronic pancreatitis. There were focal areas of parenchymal degeneration with fibrosis, protein plug formation and tubular complexes. In the pancreatic tissue of animals fed ethanol, total protein, trypsinogen (and free trypsin) were increased and amylase was decreased. While acid phosphatase was increased in all of the particulate fractions, cathepsin B was increased in the zymogen granule and mitochondrial-lysosomal fractions. Basal and post-secretin pancreatic juice did not show a significant increase in digestive or lysosomal enzymes. It is suggested that focal degenerative changes may be due to trypsin generated by intracellular activation of digestive enzymes by lysosomal enzyme cathepsin B.

On the pathogenesis of chronic alcoholic pancreatitis from the viewpoint of experimental results in rats

To elucidate the pathogenesis of chronic alcoholic pancreatitis, light-microscopic and electron microscopic observations of pancreases from Wistar strain rats given 20% ethanol ad lib, instead of water, were performed. Results were as follows: (1) In 3 (11%) rats, focal lobular unit acinar cell damage was observed under light-microscopy. In these cases, the intercalated ducts and centroacinar cells showed proliferation independently of protein plugs in ducts. (2) After ethanol intake, several degenerative changes in the acinar cells and ductular cells were observed under electron microscopy. The earliest and most consistent change was the irregular formation of microvilli and interdigitation between the parenchymal cells, accompanied by widening of the intercellular space, especially between the acinar and centroacinar cells. After three months of ethanol intake, an increase in the lysosomes and mitochondrial alteration occurred in acinar cells, and after six months of ethanol ingestion, there was tortuous ductular proliferation accompanied by the degeneration of the ductular cells. In addition to these parenchymal changes, the capillary endothelium and nervous tissue of the pancreas showed occasional degenerative changes after three to six months of ethanol intake. These results suggest that repeated degeneration and regeneration of the ductular cells results in deformation of ductular structures, with subsequent stenosis, and represents the primary event in the development of chronic alcoholic pancreatitis in rats.

Effects of different compositions of diets and chronic ethanol administration on proteolytic and antiproteolytic systems in the pancreatic tissue of rats

The effects of dietary composition in combination with chronic ethanol ingestion on pancreatic proteolytic-antiproteolytic systems were studied by submitting 192 male Wistar rats to a 12-week dietary period. The rats were fed with a standard (S), fat-rich (F), protein-rich (P), or carbohydrate-rich (C) diet after randomized division into four groups. Half of the animals in each dietary group received water and the other half a mixture of 15% (v/v) ethanol and water as their drinking solution. The C-diet caused a significant increase of BAPNA hydrolysis, which was even more pronounced in rats receiving ethanol. Casein hydrolysis was increased significantly by the C-diet, but ethanol did not have any significant effect on this. Hydrolysis of ATEE was decreased significantly by the P- and C-diets, and ethanol in combination with the S- and F-diets decreased hydrolysis of ATEE in comparison with the corresponding water-receiving groups. The trypsin-inhibiting capacity of the pancreatic tissue was significantly increased in the group receiving C- and F-diets as compared to the S-diet-receiving group of animals. It seems that the composition of the consumed diet in combination with chronic ethanol ingestion may play a role in regulating the pancreatic proteolytic-antiproteolytic system. However, these changes were not parallel. The trypsin-inhibiting capacity of pancreatic tissue was also affected by the quality of the diet.

Effect of chronic feeding of ethanol diet of "average" fat content on rat pancreas

The present study was done to determine the influence of dietary fat on the effect of ethanol on pancreatic macromolecular content and secretion. Weight-matched groups of Sprague-Dawley rats were divided into controls fed Rodent-Blox ad libitum; American Institute of Nutrition-76 (AIN-76) diet containing 12% calories as fat with 36% of carbohydrate calories replaced with 5% (weight/volume) concentration of ethanol fed ad libitum pair fed with animals given isocaloric amounts of AIN-76 diet for three to six months. Compared with Rodent-Blox fed controls, tissue content of trypsinogen, chymotrypsinogen, amylase, and lipase; specific activity and concentration of trypsinogen, chymotrypsinogen; and concentration of amylase were decreased at six months in AIN-76 fed controls. These changes did not result from diminished food intake, but were due to adaptation to the liquid diet. Animals fed AIN-76 diet plus ethanol did not show significant difference in the total content, specific activity, concentration, and secretion of digestive enzymes compared with those animals pair fed isocaloric amounts of AIN-76 diet. Activation of trypsinogen by exogenous trypsin was lower in rats fed AIN-76 diet and a similar change was observed in animals fed AIN-76 diet with ethanol for six months. These findings are in contrast to increased secretion of proteases and decreased trypsin inhibitor observed previously in animals fed ethanol in a diet containing "high" fat. These data indicate that ethanol effect on the pancreas is modified by dietary intake of fat and/or carbohydrates.

Interaction of chronic alcohol administration and diet on pancreatic acinar cell metabolism in the rat

The present study was done to determine the effect of the interaction of ethanol and an average or high-fat diet on pancreatic acinar cell function. Weight-matched groups of Sprague-Dawley rats were fed regular rat feed or average fat and high-fat liquid diets with or without 5% (w/v) concentration of ethanol for 3 months. Trypsinogen secretion was increased by the high-fat diet but not by ethanol; chymotrypsinogen secretion was decreased by the combination of ethanol and a high-fat diet, while lipase secretion was increased by a high-fat diet. Pancreatic secretory trypsin inhibitor was not significantly altered by ethanol or fat in the diet. Ethanol feeding together with a high-fat content of the diet caused complex and nonparallel changes in the secretion of the pancreatic enzymes. These data are of interest in view of the reported positive correlation between alcoholism and a high-fat content of the diet in the causation of alcoholic pancreatitis in humans.

The effect of fat-rich, protein-rich, and carbohydrate-rich diets combined with long-term ethanol ingestion on the pancreatic proteolytic proenzymes in rats

The effect of chronic alcohol ingestion on pancreatic adaptation to protein-, fat-, carbohydrate-rich and standard diets in rats was studied. Alcoholic animals received 15% (v/v) ethanol in their drinking water and controls tap water for 12 weeks. No mortality or dehydration was observed. After this diet period pancreases were removed, and specific and total activities of trypsinogen and chymotrypsinogen activities of the homogenates were determined. Ethanol itself did not have any significant effect on chymotrypsinogen or trypsinogen activities, but when combined with special diets significant increases were observed. The activity of chymotrypsinogen increased most in the alcohol and fat-rich diet group, that of trypsinogen in the alcohol and carbohydrate-rich diet group.