REDUCED REACTIVITY OF PANCREATIC EXOCRINE SECRETION IN RESPONSE TO GASTROINTESTINAL HORMONE IN WBN KOB RATS/

We compared pancreatic exocrine secretion in 5-month-old WBN/Kob rats, a model of chronic pancreatitis, with that in Wistar rats of the same age in a conscious state, Basal pancreatic secretion and pancreatic w et weight in WBN/Kob rats were lower than the values for Wistar rats. There was no difference in plasma cholecystokinin (CCK) concentration between the two types of rats. When CCK-8 was intravenously administer ed, the stimulation of pancreatic protein secretion in WBN/Kob rats wa s weaker than that in Wistar rats. When bile and pancreatic juice were diverted from the duodenum, the resulting increase in the plasma CCK concentration was similar in both types of rats, but stimulation of th e volume and protein output of pancreatic juice in WBN/Kob rats was we aker than that in Wistar rats. In addition, WBN/Kob rats exhibited lit tle increase in pancreatic wet weight because of this diversion. When secretin was intravenously administered, the stimulation of fluid secr etion in WBN/Kob rats was also weaker than that in Wistar rats, The bi nding of CCK-8 to pancreatic membrane fractions in WBN/Kob rats was mu ch weaker than that in Wistar rats. Histological findings in WBN/Kob r at pancreas showed proliferation of fibrous tissue and atrophy of acin ar cells. In conclusion, pancreatic exocrine secretion in response to the gastrointestinal hormones, CCK and secretin, was lower in WBN/Kob rats than in Wistar rats. These findings suggest that the hyposecretio n of pancreas in WBN/Kob rats is hyporeaction of pancreatic membrane t o gastrointestinal hormones.