Ethanol-induced oxidative gastrointestinal mucosal injury in human gastric mucosal cells, and protection by bismuth subsal1cylate (BSS)

Reactive oxygen species (ROS) are implicated in the pathogenesis of ethanol-induced gastroiritestinal injury. We have investigated the effects of ethanol on the enhanced production of ROS including superoxide anion (SA) and hydroxyl radicals (OH), modulation of intracellular oxidized states by laser scanning confocal microscopy (LSMC) and DNA fragmentation (DF), indices of oxidative tissue and DNA damage in normal human gastric mucosat cells (GC). We have isolated and cultured GC from Helicobacter pylori-negative endoscopic biopsies from human subjects. The integrity of mucus-producing cells in GC was confirmed by PAS staining. The induction of ROS and DNA fragmentation in GC following exposure to ethanol (15%) was assessed by cytochrome reduction (CCR), OH production, changes in intracellular oxidized states and DF. Furthermore, the protective ability of BSS was assessed at the concentrations of 25 rag/lit, 50 mg/lit and 100 mg/lit. A concentrationdependent protective ability was induced by BSS. Approx. 8.0- and 13.3-fold increased CCR and OH production were observed following incubation with ethanol respectively, while 6.7fold increased DF was observed. Approx. 20.3-fold increased fluorescence intensity was observed following incubation of GC with ethanol, demonstrating dramatic changes in the intracellular oxidized states of GC following exposure to ethanol. Preincubation of GC with 2550- and 100 mg/lit of BSS decreased ethanol-induced modulation of intracellular oxidized states in GC by 36%, 56% and 66%, demonstrating the concentration-dependent protective ability of BSS. Similar results were obtained in CCR, OH production and DF assays. The present study demonstrates that ethanol induces oxidative stress and DNA damage in GC, and BSS can significantly attenuate gastric injury by scavenging the ROS.