Abstract
Alcohol abuse is a major cause of pancreatitis. However alcohol toxicity has not been fully elucidated in the pancreas and little is known about the effect of alcohol on pancreatic ducts. We report the molecular mechanisms of ethanol-induced damage of pancreatic duct epithelial cells (PDEC). Ethanol treatment for 1, 4, and 24 h resulted in cell death in a dose-dependent manner. The ethanol-induced cell damage was mainly apoptosis due to generation of reactive oxygen species (ROS), depolarization of mitochondrial membrane potential (MMP), and activation of caspase-3 enzyme. The antioxidant N-acetylcysteine (NAC) attenuated these cellular responses and reduced cell death significantly, suggesting a critical role for ROS. Acetaldehyde, a metabolic product of alcohol dehydrogenase, induced significant cell death, depolarization of MMP, and caspase-3 activation as ethanol and this damage was also averted by NAC. Reverse transcription-polymerase chain reaction revealed the expression of several subtypes of alcohol dehydrogenase and acetaldehyde dehydrogenase. Nuclear magnetic resonance spectroscopy data confirmed the accumulation of acetaldehyde in ethanol-treated cells, suggesting that acetaldehyde formation can contribute to alcohol toxicity in PDEC. Finally, ethanol increased the leakage of PDEC monolayer which was again attenuated by NAC. In conclusion, ethanol induces apoptosis of PDEC and thereby may contribute to the development of alcohol-induced pancreatitis.
Highlights
We investigate the toxic effects of alcohol
Ethics Statement pancreatic duct epithelial cells (PDEC) and gallbladder myofibroblasts were the kind gift of Dr Sum Lee (University of Washington, affiliated with University of Hong Kong) and the procedures including animal euthanasia, prevention of pain, and consent of human tissue use were originally approved by the Animal Experiment Committee and Human Subject Review Committee at the University of Washington
Ethanol Induces Cell Damage of PDEC via Apoptosis We started to estimate cell damage induced by ethanol using two different assays, the MTS assay for cell viability and the LDH assay to detect necrotic release of LDH from cells
Summary
We investigate the toxic effects of alcohol. Cells die by necrosis and apoptosis when extracellular insults are intolerable [1,2]. Alcohol cytotoxicity is well studied in a variety of tissues including liver, brain, kidney, and gastrointestinal tract [5,6,7,8,9,10,11]. These studies have indicated that ethanol induces apoptosis through oxidative stress, mitochondrial dysfunction, and caspase activation [9,10,11,12,13,14]. Antioxidants are shown to suppress apoptotic signals induced by other stimuli such as hypoxia, tumor necrosis factor-α (TNFα), and oxidative stresses including nitric oxide, hydrogen peroxide, and superoxide [16,17,18,19]
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