RECEPTORS FOR PEPTIDE YY AND NEUROPEPTIDE-Y ON GUINEA-PIG PANCREATIC ACINI

We examined the effects of peptide YY (PYY), neuropeptide Y (NPY), and their analogues on dispersed pancreatic acini. Binding of [I-125]PYY to acini was saturable, reversible, and specific, and PYY binding was best fit with a two-site model. The relative potencies for inhibiting [I-125]PYY binding were PYY greater than or equal to NPY > NPY(13-36). There was no inhibition of binding with [Leu(31),Pro(34)]NPY, PYX-2, or pancreatic polypeptide. Both PYY and NPY (0.1 mu M) inhibited amyla se release stimulated by vasoactive intestinal polypeptide (VIP) (0.3 nM) and forskolin (1 mu M) by about 30%, but not that stimulated by ch olecystokinin-8 or bombesin. The relative potencies for inhibiting VIP -stimulated amylase release were PYY greater than or equal to NPY > NP Y(13-36), the same as those for inhibiting VIP-stimulated cAMP increas e in acini. No inhibition was detected with [Leu(31),Pro(34)]Npy. This work demonstrates Y-2 receptors on guinea pig pancreatic acini mediat ing inhibitory actions of PYY and NPY on pancreatic enzyme secretion.