Received November 9, 2006
Revised January 9, 2007
Accepted after revision March 16, 2007

¹ Graduate School of Agriculture, Hokkaido University

^* To whom correspondence should be addressed. E-mail: hira{at}chem.agr.hokudai.ac.jp.

	Abstract

Our previous study demonstrated that intestinal administration of triglycerides suppressed protein-induced increases in pancreatic exocrine secretion in pancreatico-biliary diverted (PBD) rats, though the mechanism has not been clarified. The present study was conducted to determine whether esterified fatty acids or released fatty acids are responsible for this suppression, and whether an esterified fatty acid stimulates secretion of a pancreatic inhibitory hormone, peptide YY (PYY). We examined the effects of cocoa butter or nondigestible sucrose fatty acid esters on protein-induced pancreatic secretion in conscious PBD rats whose bile-pancreatic juice (BPJ) was diverted from the proximal small intestine through a catheter. Intraduodenal administration of the protein, guanidinated casein hydrolysate (HGC, 150 mg in 1 ml), enhanced pancreatic protein and trypsin secretion. However, administration of HGC with cocoa butter (100 mg/ml) partly, and HGC with a highly esterified sucrose fatty acid ester F-10 (100 mg/ml) completely suppressed the increases in pancreatic secretion. The low-esterified, water-soluble sucrose fatty acid ester, F-160, also completely inhibited protein-induced pancreatic secretion in the presence or absence of the lipase inhibitor, orlistat. Intraduodenal administration of HGC with sucrose ester F-160 induced PYY secretion more strongly than did HGC with sucrose, which was accompanied by the suppression of HGC -induced pancreatic secretion in anesthetized PBD rats. These results suggest that the esterified fatty acid itself stimulates PYY release in the distal intestine, thereby inhibiting protein-induced pancreatic secretion.

Key Words: Gastrointestinal tract, Pancreas, Secretion