Pathogenesis of a rat model of chronic pancreatic insufficiency induced by injection of zein-oleic acid-linoleic acid solution into the pancreatic duct

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An experimental model of chronic pancreatitis was induced by a retrograde injection of the viscous solution consisting of zein-oleic acid-linoleic acid (0.05ml/100g BW) into the rat pancreatic duct. Serial microscopic studies revealed that the injected solution remained at least over 24 hr mainly in interlover ducts and partially in intralobar ducts, whereas the solution in the common bile-pancreatic duct was immediately washed out into the duodenum. The early ultra-structural changes of acinar cells were observed as decrease in zymogen granules and dilatation of the endoplasmic reticulum. Widening of acinar lumen and cellular vacuolization occurred within 24 hr at the parenchyma neighboring the small ducts filled with the zein-solution. Further decrease in cell height and dilatation of acinar lumen were accumulated and interstitial edema accompained with cellular infiltration was pronounced at 1 week. Degeneration of acini showing as tubular complexes appearance progressed afterward a … More nd led to marked atrophy with irregular fibrosis and fat replacement over a period of 6 months. In addition, irregular dilatation of major pancreatic duct and its branches with periductal fibrosis was observed at 6 months.Serum amylase level which was maximally increased 6 h after the injection was normalized on the second day and this level persisted for 6 months. As time passed, the treated rats gained weight gradually but pancreatic weight was reduced (-33% after 1 week, -69% after 6 weeks, -88% after 6 months). Pancreatic contents of protein, amylase, DNA and RNA were distinguishedly decreased as well as pancreatic weight, while hydroxyproline content was apparently increased. BT-PABA test was indicated as 54% at 6 weeks and 22% at 6 months. Although three quarters of pancreatic IRI content was lost after 6 months, overt diabetes did not occurred.Based on these results, it was considered that obstructive changes in the small ducts might play an important role in genesis and development of chronic pancreatitis. Less