Neuropeptide Y inhibits the nicotine-mediated release of catecholamines from bovine adrenal chromaffin cells

The possible role of neuropeptide Y (NPY) in catecholamine secretion was studied by using bovine adrenal chromaffin cells. NPY produced a concentration-dependent inhibition of nicotine-stimulated norepinephrine and epinephrine release from bovine chromaffin cells with IC50 (concentration of NPY which inhibits 50% of maximum release of catecholamines) values of 1.8 x 10(-9) M and 1.7 x 10(-9) M, respectively. Catecholamine release induced by 56 mM KCl was not inhibited by NPY at these concentrations but was inhibited by high concentration (2 x 10(-6) M) of NPY. This inhibition was not affected by the concentration of nicotine used for catecholamine release or the presence of alpha, beta adrenergic and muscarinic antagonists. A structurally related peptide, human pancreatic polypeptide, showed a similar inhibitory effect on catecholamine release, but peptide YY or avian pancreatic polypeptide had little or no effect. N-propionyl[3H]NPY binds to a single class of saturable binding sites on bovine adrenal medulla membranes with a KD = 0.32 +/- 0.07 nM and Bmax = 63 +/- 16 fmol/mg of protein. The rank order of potency of NPY and other structurally similar peptides to displace N-propionyl[3H]NPY from binding is human pancreatic polypeptide greater than or equal to NPY much greater than peptide YY greater than avian pancreatic polypeptide, and is correlated with their potency to inhibit catecholamine release. These results suggest a modulatory role for NPY through a specific NPY receptor in the secretion of catecholamine from the adrenal.