Effects of reactive oxygen species on actin filament polymerisation and amylase secretion in mouse pancreatic acinar cells

The present study investigates the effect of reactive oxygen species (ROS) on actin filament reorganisation and its relevance to exocytosis in pancreatic acinar cells. Treatment of pancreatic acini with cholecystokinin (CCK-8) induced spatial and temporal changes in actin filament reorganisation with an initial depolymerisation of the apical actin barrier followed by an increase in the actin filament content in the subapical area leading to amylase release. Hydrogen peroxide (H2O2) increased actin filament content and potentiated the polymerising effects of CCK-8 in these cells but abolished the disruption of the apical actin layer and amylase release induced by CCK-8, Similar to CCK-8. ROS generated by the oxidation of hypoxanthine (HX) with xanthine oxidase (XOD) induced an initial decrease in actin filaments located under the apical membrane followed by a smaller increase in the content of actin filaments in the subapical area. XOD-generated ROS are able to increase amylase release in pancreatic acini although combination with CCK-8 leads to abnormal exocytosis. We provide evidence that indicates that CCK-8- and ROS-induced actin reorganisation is entirely dependent on Ca2+ mobilisation and independent of PKC activation. The regulation of the actin cytoskeleton by ROS might be involved in radical-induced cell injury in pancreatic acinar cells. (C) 2002 Elsevier Science Inc. All rights reserved.