ANTISECRETORY EFFECTS OF PEPTIDE YY AND N EUROPEPTIDE-Y AT 3 DIFFERENT LEVELS OF THE SMALL-INTESTINE IN RATS

Objectives and methods. - The purpose of this study was to compare the effects of peptide YY(PYY) and neuropeptide Y (NPY) on VIP- and PGE2- stimulated intestinal net water flux at three different levels of the small intestine (duodenum, jejunum, ileum), by a technique of in situ closed loops in anaesthetised rats. Results. - VIP-stimulated net wate r flux was efficiently inhibited by both peptides at all three intesti nal levels studied; PYY (ID50 about 30 pmol/kg.h) was 3 to 18 fold mor e potent than NPY. PGE2-stimulated net water flux was also efficiently inhibited in the jejunum and ileum; PYY (ID50 about 10 pmol/kg.h) was 30 to 90 fold more potent than NPY. A 30% inhibition of PGE2-stimulat ed net water flux could only be achieved in the duodenum with the larg est dose of either peptide used in this study. Conclusions. - PYY and NPY display potent inhibitory effects of stimulated net water flux at the three studied levels of the small intestine, except in the PGE2-st imulated duodenum. The PYY ID50s measured suggest that PYY may have a physiological action in regulating small intestinal water flux in the rat.