Pancreatitis is a major health problem in alcoholics that causes high mortality and morbidity, and after biliary duct diseases, chronic alcohol abuse is the second major cause of chronic pancreatitis. However, the mechanism of alcohol-induced pancreatitis is poorly understood. Oxidative metabolism of ethanol catalyzed by alcohol dehydrogenase (ADH) is negligible in the pancreas, while nonoxidative metabolism of ethanol to fatty acid ethyl esters (FAEEs), catalyzed by FAEE synthase, appears to be the major mechanism of ethanol disposition in the pancreas during chronic alcohol abuse. Surprisingly, very little is known regarding the role of endogenously formed FAEEs in ethanol-induced pancreatitis. Based upon our preliminary studies showing - 14-fold increase in FAEE levels in the pancreas of hepatic ADH-deficient (ADH-) deer mice as compared to those in ADH-normal deer mice, and a dose- and time-dependent formation of FAEEs and FAEE-induced apoptosis upon ethanol exposure of ADH-deficient human hepatocellular carcinoma (HepG2) cells in culture, we hypothesize that increased formation of FAEEs is a triggering event in ethanol-induced pancreatitis, and that FAEEs and FAEE synthase can be early markers of pancreatic injury. Our preliminary studies also indicate that FAEEs are formed in rat pancreatic tumor (AR42J) cells in culture. Therefore, to investigate the toxic potential of endogenously formed FAEEs and elucidate their role in ethanol-induced pancreatic injury, we will use ADH- deer mice and AR42J cells.
In Aim 1, we will determine the levels of FAEEs in the plasma and pancreas of ADH- deer mice after ethanol exposure in a dose- and time-dependent manner, and evaluate the biochemical and morphological parameters associated with pancreatic injury. We will evaluate apoptosis in the pancreas of ADH- deer mice, and in AR42J cells, after ethanol exposure (Aim 2). Inhibitors or inducers of FAEE synthase to attenuate or augment formation of FAEEs in AR42J cells, respectively, will be used to further examine the role of endogenously formed FAEEs in ethanol-induced apoptosis and toxicity (Aim 3). Achieving our Specific Aims 1-3 should establish the role of FAEEs in ethanol-induced pancreatic injury, lay the foundation for future human studies to develop these parameters as early markers for ethanol-induced pancreatic damage, and ultimately benefit us in developing new preventive/therapeutic strategies for early intervention before irreversible damage to pancreas occurs.
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