LIGATION-INDUCED ACUTE-PANCREATITIS IN RATS AND OPOSSUMS - A COMPARATIVE MORPHOLOGIC STUDY OF THE EARLY PHASE

Bile and pancreatic duct ligation (BPDL) in rats does not induce sever e acute pancreatitis but only mild inflammation, which is self-limitin g and eventually leads to pancreatic atrophy. However, BPDL in opossum s induces severe acute necrotizing pancreatitis which uniformly leads to death within 14 days, We compared pancreatic morphologic changes af ter 24 hr of BPDL in rats and opossums. Pancreatitis histology score a nd acinar cell ultrastructural changes were evaluated. In both species , BPDL was associated with significant increases in histology score co mpared to sham controls (5.0 +/- 0.3 vs 1.5 +/- 0.3 in rats, 5.3 +/- 0 .4 vs 1.1 +/- 0.1 in opossums; mean +/- SEM, ANOVA, P < 0.05). However , there was no significant difference in histology score between rats and opossums following BPDL; histologic changes, such as white blood c ell infiltration, acinar cell vacuolation, and focal acinar cell necro sis, were similar. Acinar cell ultrastructural changes after BPDL in b oth species included dilated endoplasmic reticulum and autophagic vacu ole formation. These findings indicate that the early morphologic chan ges after BPDL in rats are quite similar to those seen early in the co urse of BPDL-induced acute necrotizing pancreatitis in opossums. As th e rat is a more economical and convenient model to study than the opos sum, this study supports the use of the rat model to conduct pilot stu dies of early events in the development of BPDL-induced acute pancreat itis. This study also suggests the potential for investigating mechani sms that may be present in the rat which protect against progressive a nd fatal acute necrotizing pancreatitis as observed in opossums after longer periods of BPDL. (C) 1994 Academic Press, Inc.