Pharmacological profile of the rat intestinal crypt peptide YY receptor vs. the recombinant rat Y5 receptor

Peptide YY and neuropeptide Y have potent antisecretory effects in rat small intestine. Scatchard analysis of [125I]peptide YY binding revealed a 10-fold higher concentration of receptors in rat jejunal crypt cells than in villus cells and no detectable receptors in colonic epithelium. Reverse transcription polymerase chain reaction analysis of neuropeptide Y Y5 receptor mRNA indicated that they are mainly expressed in rat jejunal crypts with very few or no expression in villus cells and colon epithelium, respectively. In order to determine whether neuropeptide Y Y5 receptors could represent the intestinal crypt receptor for peptide YY and neuropeptide Y, the ability of peptide YY, neuropeptide Y, pancreatic polypeptide and analogues to inhibit [125I]peptide YY binding to membrane prepared from rat crypt cells and COS-7 cells (African green monkey kidney cells) transfected with the rat neuropeptide Y Y5 receptor cDNA was tested. It appeared that several analogues displayed different inhibition constants (Ki) in the two binding assays, more especially N-alpha-acetyl-peptide YY-(22-36) which was 1200 x more potent in the crypt cell binding assay than in the recombinant neuropeptide Y Y5 receptor binding assay. These data support that the intestinal crypt peptide YY receptor is not a Y5 receptor. reserved.