Impaired Release of Peptide YY in Patients with Proctocolectomy and Ileal Pouch-Anal Anastomosis

Abstract

Peptide YY (PYY) is a gut hormone produced by endocrine cells in the distal small bowel, colon, and rectum. PYY inhibits upper gastrointestinal secretory and motor functions. The aim of this study was to determine whether basal and postprandial plasma PYY levels in patients with proctocolectomy and ileal pouch-anal anastomosis (IPAA) are reduced and to determine the relationship between plasma PYY and plasma cholecystokinin (CCK) levels. Plasma concentrations of PYY and CCK were measured before and after ingestion of a standardized breakfast in 14 IPAA patients and in 12 healthy control subjects. Basal PYY was slightly lower in the IPAA patients than in the controls (8.3 +/- 0.3 versus 9.3 +/- 1.1 pM; not significant). Ingestion of the meal induced a small but significant increase of PYY to a maximum of 10.9 +/- 0.9 pM in patients. Integrated postprandial PYY was markedly reduced in patients when compared with the controls (1725 +/- 66 pM*180min versus 3194 +/- 480 pM*180 min; P < 0.005). Plasma PYY concentrations were inversely correlated with plasma CCK concentrations in the 2nd and 3rd h after the meal (r = -0.86; P = 0.0001). PYY release in response to meal ingestion is markedly reduced but not completely absent in patients with proctocolectomy and ileal pouch-anal anastomosis. The inverse relationship between circulating PYY and CCK in the late postprandial phase is compatible with a negative feedback regulation of CCK release by endogenous PYY.