The peptide YY-preferring receptor mediating inhibition of small intestinal secretion is a peripheral Y-2 receptor: Pharmacological evidence and molecular cloning

A peptide YY (PYY)-preferring receptor [PYY > neuropeptide Y (NPY)] was pre viously characterized in rat small intestinal crypt cells, where it mediate s inhibition of fluid secretion. Here, we investigated the possible status of this receptor as a peripheral Y-2 receptor in rats. Typical Y-2 agonists (PYY3-36, NPY3-36, NPY22-36, C2-NPY) and very short PYY analogs (N-alpha - AcPYY22-36, and N-alpha -Ac-PYY25-36) acting at the intestinal PYY receptor were tested for their ability to inhibit the binding of I-125-PYY to membr anes of rat intestinal crypt cells and of CHO cells stably transfected with the rat hippocampal Y-2 receptor cDNA. Similar PYY preference was observed and all analogs exhibited comparable high affinity in both binding assays. The same held true for the specific Y-2 antagonist BIIE0246 with a K-i val ue of 6.5 and 9.0 nM, respectively. BIIE0246 completely abolished the inhib ition of cAMP production by PYY in crypt cells and transfected CHO cells. M oreover, the antagonist 1) considerably reversed the PW-induced reduction o f short-circuit current in rat jejunum mucosa in Ussing chamber and 2) comp letely abolished the antisecretory action of PW on vasoactive intestinal pe ptide (VIP)-induced fluid secretion in rat jejunum in vivo. Quantitative re verse transcription-polymerase chain reaction (RT-PCR) experiments showed t hat Y-2 receptor transcripts were present in intestinal crypt cells (3 x 10 (2) molecules/100 ng RNA,) with no expression in villus cells, in complete agreement with the exclusive binding of PW in crypt cells. Finally, a full- length Y-2 receptor was cloned by RT-PCR from rat intestinal crypt cells an d also from human small intestine. We conclude that the so-called PYY-prefe rring receptor mediating inhibition of intestinal secretion is a peripheral Y-2 receptor.