Morphologic characterization of early ligation–induced acute pancreatitis in rats

Background Bile-pancreatic duct ligation in rats causes acute pancreatic inflammation. We performed serial morphologic evaluation of the exocrine pancreas after duct ligation to facilitate further investigations using the model. Methods The pancreas was excised from 74 rats after 0, 1, 3, 5, 24 or 48 hours of duct ligation or sham surgery. A pathologist evaluated 1 hematoxylin- and eosin-stained slide from each rat. Confirmatory immunostaining was performed with markers for apoptosis (activated caspase-3), proliferation (cyclin D3), neutrophils (myeloperoxidase), and macrophages (CD68). Results Interstitial edema and white blood cell infiltration were apparent at 24 hours and increased at 48 hours. Progressive periods of duct ligation were characterized by ductular ectasia (1 to 3 hours), acinar vacuolization (5 to 48 hours), leukocytic margination and neutrophil exocytosis (5 to 48 hours), ductule epithelium hypertrophy and proliferation (24 to 48 hours), and discernible loss of zymogen granules (48 hours). Conclusions Ligation-induced acute pancreatitis in rats is a useful model to investigate early events in disease pathogenesis.