Arginine induced acute pancreatitis alters the actin cytoskeleton and increases heat shock protein expression in rat pancreatic acinar cells

Arginine induced acute pancreatitis was evaluated as a novel and distinct f orm of experimental pancreatitis with particular attention to the actin cyt oskeleton and expression of heat shock or stress proteins. Arginine induced a dose related necrotising pancreatitis in rats, as shown by histological evaluation, and an increase in serum amylase. Severe pancreatitis induced b y 4.5 g/kg arginine was accompanied by dramatic changes in the actin cytosk eleton, as visualised with rhodamine phallodin. Intermediate filaments were also disrupted, as visualised by cytokeratin 8/18 immunocytochemistry. Arg inine pancreatitis was accompanied by a stress response with a large increa se in the small heat shock protein HSP27, as well as HSP70, peaking at 24 h ours and localised to acinar cells. There was a lower increase in HSP60 and HSP90 and no effect on GRP78. HSP27 was also shifted to phosphorylated for ms during pancreatitis. A lower dose of arginine (3.0 g/kg) induced less pa ncreatitis but a larger increase in HSP70 and HSP27 expression and phosphor ylation of HSP27. Thus HSP expression can be overwhelmed by severe damage. The present work in conjunction with earlier work on caerulein induced panc reatitis indicates that changes in the actin cytoskeleton are an early comp onent in experimental pancreatitis.