ROLE OF NEUTROPHILS IN CERULEIN-INDUCED PANCREATITIS IN RATS - POSSIBLE INVOLVEMENT OF APOPTOSIS

We investigated the role of neutrophils and the involvement of apoptos is in cerulein-induced acute pancreatitis. Male Sprague-Dawley rats we re divided into 2 groups. In the control group, acute pancreatitis was induced by subcutaneous injections of cerulein. In methotrexate-treat ed group, the rats received intraperitoneal injections of methotrexate to produce neutrophil depletion before the injections of cerulein. Th e rats were sacrificed at the indicated time points until 72 h after t he first injection of cerulein. Neutrophil depletion ameliorated pancr eatic edema and vacuole formation in acinar cells during the early sta ges of cerulein-induced acute pancreatitis. Electron microscopy, DNA g el electrophoresis and in situ nick end-labeling revealed the involvem ent of apoptosis in acinar cells in cerulein-induced acute pancreatiti s. Furthermore, the number of apoptotic acinar cells in neutrophil-dep leted rats showed an about 2-fold increase during the late stages when compared with those in the control rats. Our results suggest that neu trophil depletion in cerulein-induced pancreatitis leads to ameliorati on of pancreatic injury during the early stage, and enhancement of apo ptosis by neutrophil depletion occurs during the late stage.