Drinking and driving pancreatitis: links between endoplasmic reticulum stress and autophagy

Alcohol abuse is the leading etiologic factor of pancreatitis, although many heavy drinkers do not develop pancreatic damage. Alcohol promotes pancreatitis through a combination of remote (e.g., increased gut permeability to bacterial products such as lipopolysaccharide) and more proximal effects (e.g., altered pancreatic cholinergic inputs), including oxidative damage at the level of the pancreatic acinar cell. Recent evidence indicates that alcohol exposure to rodents disturbs proteostasis in the exocrine pancreas, an effect counterbalanced by homeostatic processes that include both the unfolded protein response (UPR) and autophagy. A corollary to this notion is that pancreatitis results when adaptive responses are insufficiently robust to alleviate the cellular stress caused by alcohol.     

Alcohol and Acute Pancreatitis

Alcohol abuse is associated with the development of both acute and chronic pancreatitis. The majority of patients who abuse alcohol will not develop pancreatitis; the reasons for different susceptibilities to alcohol are unknown. Most patients who present with acute alcoholic pancreatitits will have underlying chronic disease, but up to a third will have no evidence of chronic pancreatitis. Alcohol has a number of acute effects on the pancreas that are potentially toxic. These include increasing pancreatic duct pressure, decreasing pancreatic blood flow, generating free radicals, and stimulating pathologic zymogen activation within the pancreatic acinar cell.     

Protein kinase D: A therapeutic target in experimental alcoholic pancreatitis

BackgroundAlcohol abuse, a main cause of pancreatitis, has been known to augment NF-κB activation and cell necrosis in pancreatitis. However, the underlying mechanisms are unclear. We recently reported that inhibition of protein kinase D (PKD) alleviated NF-κB activation and severity of experimental pancreatitis. Here we investigated whether PKD signaling mediated the modulatory effects of alcohol abuse on pathological responses in alcoholic pancreatitis.MethodsAlcoholic pancreatitis was provoked in two rodent models with pair-feeding control and ethanol-containing Lieber-DeCarli diets for up to 8 weeks followed by up to 7 hourly intraperitoneal injections of cerulein at 1 μg/kg (rats) or 3 μg/kg (mice). Effects of PKD inhibition by PKD inhibitors or genetic deletion of pancreatic PKD isoform (PKD3Δpanc mice) on alcoholic pancreatitis parameters were determined.ResultsEthanol administration amplified PKD signaling by promoting expression and activation of pancreatic PKD, resulted in augmented/promoted pancreatitis responses. Pharmacological inhibition of PKD or with PKD3Δpanc mice prevented the augmenting/sensitizing effect of ethanol on NF-κB activation and inflammatory responses, cell necrotic death and the severity of disease in alcoholic pancreatitis. PKD inhibition prevented alcohol-enhanced trypsinogen activation, mRNA expression of multiple inflammatory molecules, the receptor-interacting protein kinase activation, ATP depletion, and downregulation of pro-survival Bcl-2 protein in alcoholic pancreatitis. Furthermore, PKD inhibitor CID755673 or CRT0066101, administrated after the induction of pancreatitis in mouse and rat alcoholic pancreatitis models, significantly mitigated the severity of pancreatitis.ConclusionPKD mediates effect of alcohol abuse on pathological process of pancreatitis and constitutes a novel therapeutic target to treat this disease.     

Relationships among Iron,Protein Oxidation and Lipid Peroxidation Levels in Rats with Alcohol-induced Acute Pancreatitis

It has been previously shown that alcohol induces the damage of pancreatic parenchyma tissue, but the mechanism of this damage is still poorly understood. Assuming that oxygen radical damage may be the involved, we measured markers of oxidative damage in pancreatic tissue, blood serum, plasma, and whole blood of rats with early-stage alcohol-induced acute pancreatitis. Thirty-eight male Wistar rats were divided into three groups: the control group (group 1), the acute pancreatitis group 1 day (group 2), and 3 days (group 3) after the injection of ethyl alcohol into the common biliary duct, respectively. The levels of Fe in tissue and serum, whole blood viscosity, plasma viscosity, fibrinogen and homocysteine (Hcy) levels, erythrocyte and plasma malondialdehyde (MDA), and tissue and plasma protein carbonyl levels were found to be significantly higher in groups 2 and 3 than in group 1. However, the levels of reduced glutathione (GSH) in tissue and erythrocytes were significantly lower in groups 2 and 3 than in group 1. These results suggest that elevated Fe levels in serum and pancreatic tissue in rats with early-stage alcohol-induced acute pancreatitis is associated with various hemorheological changes and with oxidative damage of the pancreas.     

Metabolomic analysis to discover candidate therapeutic agents against acute pancreatitis

Novel and effective drugs against acute pancreatitis are required. Therefore, we examined the changes in the metabolite levels in the serum and pancreatic tissue of mice with cerulein- and arginine-induced pancreatitis using gas-chromatography/mass-spectrometry (GC/MS) and investigated whether these alterations affected the severity of acute pancreatitis. In the cerulein-induced pancreatitis model, 93 and 129 metabolites were detected in the serum and pancreatic tissue, respectively. In the L-arginine-induced acute pancreatitis model, 120 and 133 metabolites were detected in the serum and pancreatic tissue, respectively. Among the metabolites, the concentrations of tricarboxylic acid (TCA) cycle intermediates and amino acids were altered in pancreatitis, and in pancreatic tissue, the levels of the intermediates involved in the initial part of the TCA cycle were increased and those of the intermediates involved in the latter part of the TCA cycle were decreased. Some metabolites exhibited similar changes in both pancreatitis mouse models, e.g., the levels of glutamic acid and O-phosphoethanolamine were significantly decreased in the pancreatic tissue. Supplementation with glutamic acid and O-phosphoethanolamine attenuated the severity of cerulein-induced acute pancreatitis. Our results suggest that GC/MS-based metabolomics is capable of accurately representing the status of acute pancreatitis, leading to the discovery of therapeutic agents for pancreatitis.     

Alcohol as a Risk Factor for Cancer Burden: A Review

Alcohol is eliminated from the body by various metabolic mechanisms. The primary enzymes in such mechanism involved are alcohol dehydrogenase, aldehyde dehydrogenase, cytochrome P450 2E1, and catalase. Variations in the genes for these enzymes have been found to influence alcohol consumption. The consequences of alcohol metabolism include oxygen deficits (i.e., hypoxia) in the liver, resulting in the formation of harmful compounds (i.e., adducts) and highly reactive oxygen-containing molecules (i.e., reactive oxygen species) that can damage cell components. Approximately, worldwide 3.6 % of cancers derive from chronic alcohol drinking, including those of the upper aerodigestive tract, the liver, the colorectum and the breast. Although the mechanisms for alcohol-associated carcinogenesis are not completely understood, recent findings have focused on acetaldehyde, the first and most toxic ethanol metabolite, as a cancer-causing agent. Alcohol-related carcinogenesis may aggravate due to other factors such as smoking and being triggered by genetic susceptibility. Besides, the role of genetic polymorphisms of the alcohol-metabolizing enzymes could not be ruled out.     

Activation of pancreatic stellate cells attenuates intracellular Ca2+ signals due to downregulation of TRPA1 and protects against cell death induced by alcohol metabolites

Alcohol abuse, an increasing problem in developed societies, is one of the leading causes of acute and chronic pancreatitis. Alcoholic pancreatitis is often associated with fibrosis mediated by activated pancreatic stellate cells (PSCs). Alcohol toxicity predominantly depends on its non-oxidative metabolites, fatty acid ethyl esters, generated from ethanol and fatty acids. Although the role of non-oxidative alcohol metabolites and dysregulated Ca²⁺ signalling in enzyme-storing pancreatic acinar cells is well established as the core mechanism of pancreatitis, signals in PSCs that trigger fibrogenesis are less clear. Here, we investigate real-time Ca²⁺ signalling, changes in mitochondrial potential and cell death induced by ethanol metabolites in quiescent vs TGF-β-activated PSCs, compare the expression of Ca²⁺ channels and pumps between the two phenotypes and the consequences these differences have on the pathogenesis of alcoholic pancreatitis. The extent of PSC activation in the pancreatitis of different aetiologies has been investigated in three animal models. Unlike biliary pancreatitis, alcohol-induced pancreatitis results in the activation of PSCs throughout the entire tissue. Ethanol and palmitoleic acid (POA) or palmitoleic acid ethyl ester (POAEE) act directly on quiescent PSCs, inducing cytosolic Ca²⁺ overload, disrupting mitochondrial functions, and inducing cell death. However, activated PSCs acquire remarkable resistance against ethanol metabolites via enhanced Ca²⁺-handling capacity, predominantly due to the downregulation of the TRPA1 channel. Inhibition or knockdown of TRPA1 reduces EtOH/POA-induced cytosolic Ca²⁺ overload and protects quiescent PSCs from cell death, similarly to the activated phenotype. Our results lead us to review current dogmas on alcoholic pancreatitis. While acinar cells and quiescent PSCs are prone to cell death caused by ethanol metabolites, activated PSCs can withstand noxious signals and, despite ongoing inflammation, deposit extracellular matrix components. Modulation of Ca²⁺ signals in PSCs by TRPA1 agonists/antagonists could become a strategy to shift the balance of tissue PSCs towards quiescent cells, thus limiting pancreatic fibrosis.Subject terms: Cell death, Ion channel signalling, Gastrointestinal diseases, Preclinical research, Physiology     

Pancreatic response to endotoxin after chronic alcohol exposure: switch from apoptosis to necrosis?

Chronic alcohol consumption is known to increase the susceptibility to acute and chronic pancreatitis, and it is likely that a cofactor is required to initiate the progression to alcoholic pancreatitis. The severity and complications of alcoholic and nonalcoholic acute pancreatitis may be influenced by a number of cofactors, including endotoxemia. To explore the effect of a possible cofactor, we used endotoxin [lipopolysaccharide (LPS)] as a tool to induce cellular injury in the alcoholic pancreas. Single, increasing doses of endotoxin were injected in rats fed an alcohol or control diet and killed 24 h after the injection. We examined the mechanism by which LPS exacerbates pancreatic injury in alcohol-fed rats and whether the injury is associated with apoptosis or necrosis. We showed that chronic alcohol exposure alone inhibits apoptosis through the intrinsic pathway and the downstream apoptosis executor caspase-3 compared with the controls. Pancreatic necrosis and inflammation increased after LPS injection in control and alcohol-fed rats in a dose-dependent fashion but with a significantly greater response in the alcohol-fed animals. Caspase activities and TdT-mediated dUTP nick-end labeling positivity were lower in the alcoholic pancreas injected with LPS, whereas the histopathology and inflammation were more severe compared with the control-fed animals. Assessment of a putative indicator of necrosis, the ratio of ADP to ATP, indicated that alcohol exposure accelerates pancreatic necrosis in response to endotoxin. These findings suggest that the pancreas exposed to alcohol is more sensitive to LPS-induced damage because of increased sensitivity to necrotic cell death rather than apoptotic cell death. Similar to the liver, the pancreas is capable of responding to LPS with a more severe response in alcohol-fed animals, favoring pancreatic necrosis rather than apoptosis. We speculate that this mechanism may occur in acute alcoholic pancreatitis patients.     

Necro-inflammatory response of pancreatic acinar cells in the pathogenesis of acute alcoholic pancreatitis

The role of pancreatic acinar cells in initiating necro-inflammatory responses during the early onset of alcoholic acute pancreatitis (AP) has not been fully evaluated. We investigated the ability of acinar cells to generate pro- and anti-inflammatory mediators, including inflammasome-associated IL-18/caspase-1, and evaluated acinar cell necrosis in an animal model of AP and human samples. Rats were fed either an ethanol-containing or control diet for 14 weeks and killed 3 or 24 h after a single lipopolysaccharide (LPS) injection. Inflammasome components and necro-inflammation were evaluated in acinar cells by immunofluorescence (IF), histology, and biochemical approaches. Alcohol exposure enhanced acinar cell-specific production of TNFα, IL-6, MCP-1 and IL-10, as early as 3 h after LPS, whereas IL-18 and caspase-1 were evident 24 h later. Alcohol enhanced LPS-induced TNFα expression, whereas blockade of LPS signaling diminished TNFα production in vitro, indicating that the response of pancreatic acinar cells to LPS is similar to that of immune cells. Similar results were observed from acinar cells in samples from patients with acute/recurrent pancreatitis. Although morphologic examination of sub-clinical AP showed no visible signs of necrosis, early loss of pancreatic HMGB1 and increased systemic levels of HMGB1 and LDH were observed, indicating that this strong systemic inflammatory response is associated with little pancreatic necrosis. These results suggest that TLR-4-positive acinar cells respond to LPS by activating the inflammasome and producing pro- and anti-inflammatory mediators during the development of mild, sub-clinical AP, and that these effects are exacerbated by alcohol injury.     

Calcitonin gene-related peptide can attenuate or augment pancreatic damage in caerulein-induced pancreatitis in rats.

We have recently shown that treatment with calcitonin gene-related peptide (CGRP) before and during induction of acute pancreatitis exhibits a protective effect against pancreatic damage evoked by overdose of caerulein. Studies in the stomach have shown that administration of CGRP exhibits dual action on gastric mucosa, CGRP administration before induction of gastric lesions, protects gastric mucosa against damage, whereas treatment with this peptide after development of gastric ulcer exacerbates mucosal injury. These observations prompt us to determine the influence of CGRP administrated before and after induction of pancreatitis on development and evolution of pancreatic tissue damage. METHODS: Acute pancreatitis was induced by s.c. infusion of caerulein (10 microg/kg/h) for 5 h. CGRP was administrated (10 microg/kg s.c. per dose) 30 min prior to caerulein infusion and 3 h later during caerulein infusion or at the time 1 h, 4 h and 7 h after the end of caerulein infusion. Rats were sacrificed at the time 0 h, 3 h or 9 h after cessation of caerulein administration. The pancreatic blood flow (PBF), plasma activity of amylase, plasma interleukin-1beta concentration, cell proliferation, biochemical and morphological signs of pancreatitis were examined. RESULTS: Caerulein-induced pancreatitis (CIP) led to 42% decrease in DNA synthesis, 30% inhibition of PBF, as well as, a significant increase in pancreatic weight, plasma amylase activity, plasma interleukin-1beta concentration, and development of the histological signs of pancreatic damage (edema, leukocyte infiltration and vacuolization). Treatment with CGRP prior and during induction of CIP attenuated the pancreatic damage what was manifested by partial reversion of the drop in DNA synthesis (40.9+1.7 v. 34.2+2.0 dpm/microg DNA) and PBF (83+3% v. 70+3%). Increases in pancreatic weight and plasma interleukin-1beta were reduced. Morphology showed improvement of pancreatic integrity. Administration of CGRP after induction of CIP aggravated pancreatic damage what was manifested by additional decrease in PBF and DNA synthesis. Also pancreatic weight as well as histological signs of pancreatic damage were increased. CONCLUSIONS: (1) Administration of CGRP before and during induction of pancreatitis protects pancreas against pancreatic damage. (2) Treatment with CGRP after development of CIP aggravates pancreatic damage.     

Alcoholic pancreatitis in rats: injury from nonoxidative metabolites of ethanol

The mechanism by which alcohol injures the pancreas remains unknown. Recent investigations suggest a role for fatty acid ethyl ester (FAEE), a nonoxidative metabolite of ethanol, in the pathogenesis of alcohol pancreatitis. In this study, we characterized ethanol-induced injury in rats and evaluated the contribution of oxidative and nonoxidative ethanol metabolites in this form of acute pancreatitis. Pancreatic injury in rats was assessed by edema, intrapancreatic trypsinogen activation, and microscopy after infusing ethanol with or without inhibitors of oxidative ethanol metabolism. Plasma and tissue levels of FAEE and ethanol were measured and correlated with pancreatic injury. Ethanol infusion generated plasma and tissue FAEE and, in a dose-dependent fashion, induced a pancreas-specific injury consisting of edema, trypsinogen activation, and formation of vacuoles in the pancreatic acini. Inhibition of the oxidation of ethanol significantly increased both FAEE concentration in plasma and pancreas and worsened the pancreatitis-like injury. This study provides direct evidence that ethanol, through its nonoxidative metabolic pathway, can produce pancreas-specific toxicity in vivo and suggests that FAEE are responsible for the development of early pancreatic cell damage in acute alcohol-induced pancreatitis.     

A rat model reproducing key pathological responses of alcoholic chronic pancreatitis

Although alcohol abuse is the major cause of chronic pancreatitis, the pathogenesis of alcoholic chronic pancreatitis (ACP) remains obscure. A critical obstacle to understanding the mechanism of ACP is lack of animal models. Our objective was to develop one such model. Rats were pair-fed for 8 wk ethanol or control Lieber-DeCarli liquid diet. For the last 2 wk, they received cyclosporin A (CsA; 20 mg/kg once daily) or vehicle. After 1 wk on CsA, one episode of acute pancreatitis was induced by four 20 microg/kg injections of cerulein (Cer); controls received saline. Pancreas was analyzed 1 wk after the acute pancreatitis. CsA or Cer treatments alone did not result in pancreatic injury in either control (C)- or ethanol (E)-fed rats. We found, however, that alcohol dramatically aggravated pathological effect of the combined CsA+Cer treatment on pancreas, resulting in massive loss of acinar cells, persistent inflammatory infiltration, and fibrosis. Macrophages were prominent in the inflammatory infiltrate. Compared with control-fed C+CsA+Cer rats, their ethanol-fed E+CsA+Cer counterparts showed marked increases in pancreatic NF-kappaB activation and cytokine/chemokine mRNA expression, collagen and fibronectin, the expression and activities of matrix metalloproteinase-2 and -9, and activation of pancreatic stellate cells. Thus we have developed a model of alcohol-mediated postacute pancreatitis that reproduces three key responses of human ACP: loss of parenchyma, sustained inflammation, and fibrosis. The results indicate that alcohol impairs recovery from acute pancreatitis, suggesting a mechanism by which alcohol sensitizes pancreas to chronic injury.     

Effect of ischemic preconditioning on pancreatic regeneration and pancreatic expression of vascular endothelial growth factor and platelet-derived growth factor-A in ischemia/reperfusion-induced pancreatitis.

Ischemic preconditioning has been shown to protect several organs from ischemia/reperfusion-induced injury. In the pancreas, protective effect of ischemic preconditioning has been shown against pancreatitis evoked by ischemia/reperfusion, as well as by caerulein. However, the effect of ischemic preconditioning on the course of acute pancreatic is unclear. The aim of our study was to evaluate the influence of ischemic preconditioning on pancreatic regeneration and pancreatic presence of platelet-derived growth factor-A (PDGF-A) and vascular endothelial growth factor (VEGF) in the course of ischemia/reperfusion-induced pancreatitis. METHODS: In male Wistar rats, ischemic preconditioning of the pancreas was performed by short-term clamping of celiac artery (twice for 5 min with 5 min interval). Acute pancreatitis was induced by clamping of inferior splenic artery for 30 min followed by reperfusion. Rats were sacrificed 1, 5, 12 h or 1, 2, 3, 5, 7, 9 and 21 days after the start of reperfusion. Severity of acute pancreatitis and pancreatic regeneration were determined by biochemical and morphological examination, expression of growth factors was determined by immunohistochemical analysis. RESULTS: In ischemia/reperfusion-induced pancreatitis, the pancreatic damage reached the maximal range between the first and second day of reperfusion, and was followed by subsequent pancreatic regeneration. Ischemic preconditioning alone caused mild passing pancreatic damage and an increase in plasma concentration of pro-inflammatory interleukin-1 and anti-inflammatory interleukin-10. Ischemic preconditioning applied before ischemia/reperfusion-induced pancreatitis reduced morphological and biochemical signs of the pancreatitis-evoked pancreatic damage and accelerated pancreatic regeneration. This effect was associated with improvement of pancreatic blood flow. Ischemic preconditioning, ischemia/reperfusion-induced pancreatitis and their combination increased the presence of VEGF in acinar and islet cells, and immunostaining for PDGF-A in blood vessels. This effect was maximally pronounced after combination of ischemic preconditioning plus pancreatitis and occurred earlier than after pancreatitis alone. CONCLUSIONS: Ischemic preconditioning reduces pancreatic damage and accelerates pancreatic healing in the course of ischemia/reperfusion-induced pancreatitis. This effect is associated with the increase in plasma concentration of anti-inflammatory interleukin-10, improvement of pancreatic blood flow and alteration of pancreatic immunohistochemical expression of PDGF-A and VEGF.     

Protease-activated receptor-2 exerts contrasting model-specific effects on acute experimental pancreatitis

Protease-activated receptor-2 (PAR2) is a 7-transmembrane G-protein-coupled tethered ligand receptor that is expressed by pancreatic acinar and ductal cells. It can be physiologically activated by trypsin. Previously reported studies (Namkung, W., Han, W., Luo, X., Muallem, S., Cho, K. H., Kim, K. H., and Lee, M. G. (2004) Gastroenterology 126, 1844-1859; Sharma, A., Tao, X., Gopal, A., Ligon, B., Andrade-Gordon, P., Steer, M. L., and Perides, G. (2005) Am. J. Physiol. 288, G388-G395) have shown that PAR2 activation exerts a protective effect on the experimental model of pancreatitis induced by supramaximal secretagogue (caerulein) stimulation. We now show that PAR2 exerts a worsening effect on a different model of experimental pancreatitis, i.e. one induced by retrograde pancreatic ductal infusion of bile salts. In vitro studies using freshly prepared pancreatic acini show that genetic deletion of PAR2 reduces bile salt-induced pathological calcium transients, acinar cell injury, and activation of c-Jun N-terminal kinase, whereas genetic deletion of PAR2 has the opposite or no effect on these pancreatitis-related events when they are elicited, in vitro, by caerulein stimulation. Studies employing a combination of trypsin inhibition and activation of PAR2 with the activating peptide SLIGRL show that all these differences indeed depend on the activation of PAR2. These studies are the first to report that a single perturbation can have model-specific and opposite effects on pancreatitis, and they underscore the importance of performing mechanistic pancreatitis studies using two dissimilar models of the disease to detect idiosyncratic, model-specific events. We suggest PAR2 activation exerts a worsening effect on the severity of clinical pancreatitis and that interventions interfering with PAR2 activation may be of benefit in the treatment of patients with severe pancreatitis.     

Comparative effects of water immersion pretreatment on three different acute pancreatitis models in rats.

Cells respond to stress by upregulating the synthesis of cytoprotective heat shock proteins (HSPs) and antioxidant enzymes. The aim of this study was to compare the effects of cold (CWI) or hot water immersion (HWI) stress on three different acute pancreatitis models (cholecystokinin octapeptide (CCK), sodium taurocholate (TC), and L-arginine (Arg)). We examined the levels of pancreatic HSP60, HSP72, and antioxidants after the water immersion stress. Male Wistar rats were injected with CCK, TC, or Arg at the peak level of pancreatic HSP synthesis, as determined by Western blot analysis. HWI significantly elevated HSP72 expression and CWI significantly increased HSP60 expression in the pancreas. Water immersion stress decreased the levels of pancreatic antioxidants. CWI and-HWI pretreatment ameliorated most of the examined laboratory and morphological parameters of CCK-induced pancreatitis. CWI pretreatment decreased pancreatic edema and the serum amylase level; however, the morphological damage was more severe in TC-induced acute pancreatitis. Overall, CWI and HWI pretreatment only decreased the serum cytokine concentrations in Arg-induced pancreatitis. CWI and HWI resulted in differential induction of pancreatic HSP60 and HSP72 and the depletion of antioxidants. The findings suggest the possible roles of HSP60 and (or) HSP72 (but not that of the antioxidant enzymes) in the protection against CCK- and TC-induced acute pancreatitis. Unexpectedly, CWI pretreatment was detrimental to the morphological parameters of TC-induced pancreatitis. It was demonstrated that CWI and HWI pretreatment only influenced cytokine synthesis in Arg-induced pancreatitis.     

Occurrence of pancreatic ductal cell dysplasia in rats fed with a high fat diet and ethanol

The effects of alcohol and diet on acute pancreatitis were studied in 192 male Wistar rats. The animals were fed with standard laboratory food up to three months of age and, after that, were divided into four groups of 48 animals, each group receiving a different diet: standard, fat-rich, protein-rich or carbohydrate-rich. In each diet group, 24 animals obtained 15% (v/v) ethanol in their drinking solution while the other 24 rats had water ad libitum. The diet period lasted for 12 weeks, after which acute experimental pancreatitis was induced under diethyl ether anesthesia by ductal injection of rat bile into the pancreatic ducts. Moderate or severe ductal cell dysplasia developed in three of the 15 survivors in the group fed with a high-fat diet and 15% ethanol in their drinking solution. Mild acute pancreatitis was histologically found in 13 rats and moderate pancreatitis in one rat in this group. One rat did not show any pancreatic parenchymal changes. Two of the rats with ductal cell dysplasia had mild pancreatitis and the pancreas of the third rat was normal in this respect. Dysplastic changes were not found in any other experimental group used in the study. The observation is statistically significant at p less than 0.025 level. The results indicate that alcohol and a high fat diet together might have a carcinogenic effect on pancreatic ductal epithelium in rats.     

Alcohol redirects CCK-mediated apical exocytosis to the acinar basolateral membrane in alcoholic pancreatitis

The molecular mechanism of clinical alcohol-induced pancreatitis remains vague. We had reported that experimental high-dose cholecystokinin (CCK)-induced pancreatitis is in part because of excessive aberrant basolateral exocytosis. High-dose CCK caused Munc18c on basolateral plasma membrane (BPM) to dissociate from syntaxin (Syn)-4, activating Syn-4 to complex with plasma membrane (PM)-SNAP-23 and granule-VAMP to mediate basolateral exocytosis. We now hypothesize that alcohol could render the acinar cell BPM conducive to exocytosis by a similar mechanism. Weakly stimulating postprandial doses of alcohol (20-50 mM) inhibited postprandial low-dose CCK-stimulated secretion by blocking physiologic apical exocytosis and redirecting exocytosis to less-efficient basal PM (visualized by FM1-43 fluorescence imaging) and lateral PM sites (electron microscopy). Alcohol or low-dose CCK had no effect on PM-Munc18c, but alcohol preincubation enabled low-dose CCK to displace Munc18c from BPM, leading to SNARE complex assembly in the BPM. Similarly, alcohol diet-fed rats did not exhibit morphologic defects in the pancreas nor affected PM-Munc18c behavior, but subsequent intraperitoneal injections of low-dose CCK analog cerulein caused Munc18c displacement from BPM and cytosolic degradation, which contributed to pancreatitis. We conclude that alcohol induces BPM-Munc18c to become receptive to postprandial CCK-induced displacement into the cytosol, a process which facilitates SNARE complex assembly that in turn activates restricted BPM sites to become available for aberrant exocytosis into the interstitial space, where zymogen activation would take place and cause pancreatitis.