CCK and PYY do not participate in the delayed inhibition of pancreatic secretion, after stimulation by duodenal oleic acid infusion.

The role played by CCK in the stimulation of pancreatic secretion by duodenal infusion of oleic acid in conscious rats was studied using a potent and specific CCK receptor antagonist. CR-1409 did not alter basal secretion, which does not require CCK. The three doses of CR-1409 that were used (2, 4 and 8 mg/kg/h) suppressed the protein response to duodenal infusion of oleic acid and significantly enhanced the delayed inhibition normally observed in control rats (-81%, -87% and -88% vs. -51% of basal in controls). CR-1409 dose-dependently reduced the volume of pancreatic secretion after duodenal infusion of oleic acid (0.40 +/- 0.02, 0.36 +/- 0.02, 0.34 +/- 0.03 vs. 0.48 +/- 0.04 ml/30 min for 2, 4, 8 mg/kg/h and controls, respectively) and revealed a delayed inhibition of volume and a slight reduction of bicarbonate secretion. CCK appears to be directly responsible for the protein and also water response to duodenal infusion of oleic acid, and to be indirectly involved in bicarbonate stimulation. PYY antiserum significantly augmented protein output after duodenal infusion of oleic acid (10.75 +/- 1.40, 14.10 +/- 1.60 vs. 8.60 +/- 1.20 mg/30 min, 1 microliter, 2 microliters and controls), but failed to modify the delayed inhibition: PYY modulates the response to duodenal infusion of oleic acid and is not involved in the delayed inhibition, which was shown to be also present for volume, but which is normally masked by the action of CCK.