Abstract

A peptide YY (PYY)-preferring receptor [PYY > neuropeptide Y (NPY)] was previously characterized in rat small intestinal crypt cells, where it mediates inhibition of fluid secretion. Here, we investigated the possible status of this receptor as a peripheral Y₂ receptor in rats. Typical Y₂ agonists (PYY_3–36, NPY_3–36, NPY_13–36, C2-NPY) and very short PYY analogs (N-α-Ac-PYY_22–36 andN-α-Ac-PYY_25–36) acting at the intestinal PYY receptor were tested for their ability to inhibit the binding of¹²⁵I-PYY to membranes of rat intestinal crypt cells and of CHO cells stably transfected with the rat hippocampal Y₂ 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 Y₂ antagonist BIIE0246 with a K _i value of 6.5 and 9.0 nM, respectively. BIIE0246 completely abolished the inhibition of cAMP production by PYY in crypt cells and transfected CHO cells. Moreover, the antagonist 1) considerably reversed the PYY-induced reduction of short-circuit current in rat jejunum mucosa in Ussing chamber and 2) completely abolished the antisecretory action of PYY on vasoactive intestinal peptide (VIP)-induced fluid secretion in rat jejunum in vivo. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) experiments showed that Y₂ receptor transcripts were present in intestinal crypt cells (3 × 10²molecules/100 ng RNA_T) with no expression in villus cells, in complete agreement with the exclusive binding of PYY in crypt cells. Finally, a full-length Y₂ receptor was cloned by RT-PCR from rat intestinal crypt cells and also from human small intestine. We conclude that the so-called PYY-preferring receptor mediating inhibition of intestinal secretion is a peripheral Y₂receptor.