Disruption of cholecystokinin (CCK)-B receptor gene did not modify bile orpancreatic secretion or pancreatic growth: A study in CCK-B receptor gene knockout mice

Pancreatic exocrine function and bile secretion were examined in cholecysto kinin (CCK)-B receptor gene-targeted mice and compared among different geno types [i.e., CCK-B receptor gene: (+/+), wild-type; (+/-), heterozygous; an d (-/-), homozygous deficient]. The histology and protein concentrations in the pancreas also were examined. Amylase release from the dispersed acini was examined in vitro by using the various doses of CCK-8, carbachol, and s ecretin. In vivo, the bile and pancreatic juice were collected, and the con centrations of amylase and bile acid were measured in anesthetized mice. Th e responses to CCK (100 pmol/kg) or acetyl-beta-methylcholine (500 nmol/kg) were examined. In vitro studies showed that the maximal effective concentr ations of CCK-8 (10(-10) M), carbachol (10(-5) M), and secretin (5 x 10(-7) M) were comparable for all genotypes. Fluid, amylase, and bile acid output s in vivo also were comparable for all genotypes. Pancreatic wet weight and protein concentrations were not significantly different, and no abnormal f indings were observed on histologic examination in any genotype. These resu lts indicated that the CCK-B receptor has no role in pancreatic growth, exo crine secretion, or bile secretion in adult mice.