Cigarette Smoke Increases Apoptosis in the Gastric Mucosa: Role of Epidermal Growth Factor

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Abstract
Background/Aims: Apoptosis is a common mechanism for the regulation of cell loss. It is associated with both tissue atrophy and metaplasia. Cigarette smoking has tremendous adverse effects on the stomach and also increases the risk of gastric cancer. This action may be through the change in apoptosis in the stomach. The aim of this study was to examine the effect of cigarette smoking on apoptosis in the gastric mucosa and the possible role of epidermal growth factor (EGF) in this action. Methods: Gastric blood flow was assessed by the laser Doppler technique. Serum and gastric mucosal EGF levels were measured by RIA. Gastric mucosal apoptosis was determined using TdT-mediated dUTP-biotin nick end labeling (TUNEL). Results: Cigarette smoke exposure decreased serum EGF which was accompanied by a reduction in gastric blood flow. Meanwhile, gastric mucosal cell apoptosis was increased. Administration of EGF (20 μg/kg i.v.) before each cigarette smoke exposure reversed these actions. Removal of salivary glands induced similar effects on the gastric blood flow, apoptosis, and serum EGF level as with cigarette smoke exposure. Conclusion: A reduction in serum EGF was involved in the decrease in gastric blood flow and increase in gastric mucosal apoptosis caused by cigarette smoking.