Changes in plasma and duodenal cholecystokinin concentrations after pancreatic duct occlusion in rats.

The changes in plasma and duodenal cholecystokinin (CCK) concentrations after pancreatic duct occlusion were examined in rats. The rats were sacrificed 1, 3, 7, 10, 14, and 30 days after occlusion of the duct. Histological examination showed acute inflammation on days 1 and 3 after duct occlusion, interstitial fibrosis and regenerative changes on days 7, 10, and 14, and pancreatic atrophy on day 30. The plasma CCK concentration increased from 0.45 pM to 2.0 pM after the occlusion and then remained high throughout the observation period. In contrast to the stable increase in plasma CCK concentration, the CCK content in the duodenum increased on days 1 and 3, decreased on day 7, increased on day 10, reaching over the control level on day 14, and then returned to the control level on day 30. Administration of boiled and 10-fold concentrated rat pancreatic juice or human pancreatic secretory trypsin inhibitor for seven days after pancreatic duct occlusion reversed the decrease in duodenal CCK content. The major molecular forms of duodenal CCK were CCK-8, -33, and -58. These results indicate that (1) basal plasma CCK concentration did not reflect the duodenal CCK content, (2) duodenal CCK content was well correlated with a decrease in inflammation in the pancreas, and (3) a nonenzymatic component in the pancreatic juice reversed the decrease in duodenal CCK content and body weight caused by pancreatic duct occlusion.