Identification of multiple neuropeptide Y receptor subtypes in the human frontal cortex.
Recently, we found abundant mRNA and binding sites for neuropeptide Y Y1-like receptors in the human cerebral cortex. However, an earlier study using indirect labeling methods failed to detect substantial neuropeptide Y1-like receptor binding in numerous areas of the human brain, including the cerebral cortex. To resolve the disparity in these findings, we characterized the neuropeptide Y receptor subtypes labeled with [125I]peptide YY in homogenates of human frontal cortex. Competition experiments using 100 pM [125I]peptide YY binding to human frontal cortex homogenates indicated predominantly neuropeptide Y Y2 receptors are labeled with this concentration of ligand. However, saturation analysis of [125I]peptide YY binding to frontal cortex membranes resulted in isotherms best characterized by a two-site fit. Binding of [125I]peptide YY to the high affinity (Kd = 40 pM) binding site was prevented using a 100 nM concentration of the neuropeptide Y Y2 receptor agonist peptide YY-(3-36). By masking the higher affinity site, we found a low affinity [125I]peptide YY binding site (Kd = 1.4 nM) exhibiting a pharmacology consistent with a neuropeptide Y Y1-like receptor. It appears that neuropeptide Y Y2 receptors are the predominant subtype labeled with low concentrations of[125I]peptide YY and that the neuropeptide Y Y1 receptor is a low affinity [125I]peptide YY binding site in the human frontal cortex.
Statnick
M A
MA
Lilly Research Laboratories. Eli Lilly and Company, Indianapolis, IN 46285, USA.
Schober
D A
DA
Gehlert
D R
DR
D001665:Binding Sites; D002540:Cerebral Cortex / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000378:metabolism; D019894:Peptide YY / Q000378:metabolism; D011485:Protein Binding; D011869:Radioligand Assay; D017476:Receptors, Neuropeptide Y / Q000145:classification* / Q000378:metabolism
D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D017476:Receptors, Neuropeptide Y; D019894:Peptide YY