CHARACTERIZATION OF NEUROPEPTIDE-Y (NPY) RECEPTORS IN HUMAN HIPPOCAMPUS

We identified a 50 kDa neuropeptide Y (NPY) receptor from human hippocampus by affinity labeling. NPY specific binding and labeling of the receptor were inhibited in parallel by increasing concentrations of unlabeled NPY (IC50 = 0.27 nM and 0.18 nM, respectively). Peptide YY (PYY), but none of the pancreatic polypeptides, was as effective as NPY in displacing [I-125]NPY. NPY fragments inhibited binding with the rank order of potency: NPY > NPY 13-36 > NPY 20-36 greater-than-or-equal-to NPY 18-36 > NPY 1-36 free acid greater-than-or-equal-to NPY 26-36. These results demonstrate that the human hippocampal NPY receptor is a 50 kDa protein fitting the classification of a Y2 receptor subtype.