Pancreatic injury in hepatic alcohol dehydrogenase-deficient deer mice after subchronic exposure to ethanol

Abstract

Pancreatitis caused by activation of digestive zymogens in the exocrine pancreas is a serious chronic health problem in alcoholic patients. However, mechanism of alcoholic pancreatitis remains obscure due to lack of a suitable animal model. Earlier, we reported pancreatic injury and substantial increases in endogenous formation of fatty acid ethyl esters (FAEEs) in the pancreas of hepatic alcohol dehydrogenase (ADH)-deficient (ADH−) deer mice fed 4% ethanol. To understand the mechanism of alcoholic pancreatitis, we evaluated dose-dependent metabolism of ethanol and related pancreatic injury in ADH− and hepatic ADH-normal (ADH+) deer mice fed 1, 2 or 3.5% ethanol via Lieber-DeCarli liquid diet daily for 2 months. Blood alcohol concentration (BAC) was remarkably increased and the concentration was ~1.5-fold greater in ADH− vs. ADH+ deer mice fed 3.5% ethanol. At the end of the experiment, remarkable increases in pancreatic FAEEs and significant pancreatic injury indicated by the presence of prominent perinuclear space, pyknotic nuclei, apoptotic bodies and dilation of glandular ER were found only in ADH− deer mice fed 3.5% ethanol. This pancreatic injury was further supported by increased plasma lipase and pancreatic cathepsin B (a lysosomal hydrolase capable of activating trypsinogen), trypsinogen activation peptide (by-product of trypsinogen activation process) and glucose-regulated protein 78 (endoplasmic reticulum stress marker). These findings suggest that ADH-deficiency and high alcohol levels in the body are the key factors in ethanol-induced pancreatic injury. Therefore, determining how this early stage of pancreatic injury advances to inflammation stage could be important for understanding the mechanism(s) of alcoholic pancreatitis.

Ethanol metabolism, oxidative stress, and endoplasmic reticulum stress responses in the lungs of hepatic alcohol dehydrogenase deficient deer mice after chronic ethanol feeding

“…In our previous study, we found significant deaths in hepatic alcohol dehydrogenase (ADH)-deficient (ADH − ) deer mice vs. hepatic ADH normal (ADH + ) deer mice fed 4% ethanol daily for 2 months (Bhopale et al, 2006). Therefore, in these studies, we reduced ethanol exposure to 3.5% in the diet, as no significant deaths were found at this concentration of ethanol fed daily for 2 months (Kaphalia et al ., 2010). …”

“…Hepatic ADH − deer mice are naturally deficient in hepatic class I ADH and more susceptible to ethanol toxicity as compared to ADH + deer mice (Bhopale et al ., 2006; Kaphalia et al ., 2010). Multiple genes code for hepatic ADH in deer mice.…”

“…Because ethanol overconsumption impairs hepatic ADH, some individuals may have an increased time-weighted exposure to ethanol, as detailed in our previous studies (Bhopale et al ., 2006; Kaphalia et al ., 2010). However, chronic ethanol feeding also induces hepatic cytochrome P450 2E1, another potential metabolic pathway, with a different profile of metabolites (Lieber, 2004; Cederbaum, 2010), which may have overlapping or distinct toxicities.…”

Translational Implications of the Alcohol-Metabolizing Enzymes, Including Cytochrome P450-2E1, in Alcoholic and Nonalcoholic Liver Disease

“…Bound FAEEs can be accumulated and may serve as potential uncouplers of the mitochondrial oxidative phosphorylation, as demonstrated with ethyl oleate (Lange, 1982;Laposata, 1998;Lange & Sobel, 1983). Alternatively, FAEEs can stimulate apoptosis in pancreatic acinar cells with elevated calcium-related toxicity with decreased ATP synthesis (Criddle et al, 2006(Criddle et al, , 2004Kaphalia et al, 2010). On the other hand, recent results demonstrated that exogenous ethyl esters of n-3 fatty acids including eicosatetrapentaenoic acid and docosahexaenoic acid show protective effects against obesity-related metabolic syndrome (Depner, Philbrick, & Jump, 2013;Mori et al, 1999;Pérez-Echarri et al, 2008, 2009Pérez-Matute, Pérez-Echarri, Martínez, Marti, & Moreno-Aliaga, 2007;Spencer et al, 2013).…”

Utility of Genetically Modified Animal Models for Drug Metabolism and Drug Transporters

“…A strain of deer mice (Peromyscus maniculatus) naturally deficient in ADH [180] has been used to study various aspects of ethanol metabolism [181,182]. In animals fed a 4% ethanol diet for 60 days, these studies demonstrated increased nonoxidative metabolism of ethanol to fatty acid ethyl esters in ADH-/-versus WT animals, in addition to increased mortality and histological changes to the liver and pancreas.…”