LOCALIZATION OF RAT PANCREATITIS-ASSOCIATED PROTEIN DURING BILE SALT-INDUCED PANCREATITIS

Background & Aims: Pancreatitis-associated protein (PAP), which is ove rexpressed in pancreatic acinar cells, appears in pancreatic juice and serum after acute pancreatitis. The aim of this study was to examine intracellular localization of PAP and amylase in healthy rat pancreas and pancreatitis pancreas to ascertain PAP transport from the rough en doplasmic reticulum to the zymogen granules into the acinar lumen. Met hods: Control rats and vats with taurocholate-induced pancreatitis wer e killed after 24 hours. Pancreata prepared for light and electron mic roscopy were used for amylase and PAP detection with specific antibodi es. Results: Induced acute pancreatitis disturbed the gross histology and ultrastructure of the acinar cells with the formation of new intra cellular fibrous material into the cytoplasm, which was also found int o the acinar lumen. PAP is almost absent from normal acinar cells; aft er acute pancreatitis, it appears in rough endoplasmic reticulum, it i s strongly present in normal and abnormal zymogen granules, and it rem ains an important component of the fibrous material. Except for its ex clusive presence in fibrous material, PAP is always colocalized with a mylase in the other cell compartments. Conclusions: These observations show that the accumulated PAP into the acinar cells in response to ac ute pancreatitis behaves like all the other secretory proteins with th e exception that it also accumulates in a new fibrillous cellular stru cture also found in the acinar lumen.