Background: To further establish its role in the ileal brake mechanism, we determined the effect of the distal gut hormone peptide YY (PYY) on gallbladder motility and plasma gut hormones during the cephalic phase of meal stimulation.
Methods: Eight healthy volunteers were studied in a randomized crossover design, with or without intravenous infusion of a physiological dose of PYY. On each occasion, subjects underwent modified sham feeding followed by real feeding.
Results: PYY reduced gallbladder emptying in response to modified sham feeding from 23 +/- 5% to 5 +/- 7% (P < 0.01) and integrated plasma pancreatic polypeptide from 2337 +/- 397 pmol/L x 90 min to 903 +/- 232 pmol/L x 90 min (P < 0.01). PYY enhanced plasma cholecystokinin in response to real feeding from 53 +/- 9 pmol/L x 90 min to 82 +/- 17 pmol/L x 90 min (P < 0.05), but did not significantly affect maximum gallbladder emptying and tended to decrease plasma pancreatic polypeptide.
Conclusion: Circulating PYY suppresses the cephalic phase of postprandial gallbladder emptying, but not meal stimulated maximum emptying. The results support the hypothesis that the effect of PYY on gallbladder emptying is mediated by vagal-dependent rather than cholecystokinin-dependent pathways.