Characterization of peptide YY receptors in rabbit colonic mucosa

Quantitative receptor autoradiography localized a high-affinity binding site for ¹²⁵I-peptide YY to the mucosa in rabbit distal colon. Scatchard binding analysis revealed a single-affinity binding site (K_D = 0.29 nM) with binding specificity similar to other peptide YY-preferring receptors (peptide YY ≥ neuropeptide Y > pancreatic polypeptide). Radioligand binding studies using colonic mucosal membranes confirmed high-affinity peptide YY binding sites (K_D = 0.26 nM) with time, temperature, and protein dependence, as well as saturability characteristic of receptor-ligand binding. Selective peptide analogues showed a subpopulation of these ¹²⁵I-peptide YY binding sites to resemble the Y₁-type neuropeptide Y receptor. Peptide YY may exert local antisecretory effects on the colonic epithelium via these binding sites.