Exocrine function of caerulein-induced acute pancreatitis in anesthetized rats

Exocrine function was studied in anesthetized rats that had received two specific doses of caerulein (maximal stimulation and supramaximal stimulation). Male Wistar rats (body weight, 200-250 g) were divided into three groups: the control group (4-h saline infusion), the maximal stimulation group (0.25 microgram/kg per h caerulein for 4 h), and the caerulein pancreatitis group (10 micrograms/kg per h for 4h). Histologically, interstitial edema and cytoplasmic vacuolization were observed only in the caerulein pancreatitis group, with no abnormal findings in the other groups. The volume of pancreatic juice was significantly increased in both the maximal stimulation group and the caerulein pancreatitis group. The protein output and the amylase output in the 1st h of caerulein infusion were also significantly increased, to 459% and 338% in the maximal stimulation group, and to 925% and 1430% respectively, in the caerulein pancreatitis compared to the baseline values. We also found that the pancreatic juice of the caerulein pancreatitis group contained precipitated protein, and high trypsin activity, and protein degradation was confirmed by electrophoresis. These findings were not observed in the other groups. These results strongly suggest that hypersecretion and the appearance of trypsin activity in pancreatic juice plays an important role in the induction of histological changes in this pancreatitis model in anesthetized rats.