Labeling of neuropeptide Y receptors in SK-N-MC cells using the novel, nonpeptide Y1 receptor-selective antagonist [3H]BIBP3226

The binding of tritium-labelled BIBP3226, N2-(diphenylacetyl)-N-[(4-hydroxy-phenyl)methyl]-D-arginine amide, to human neuroblastoma SK-N-MC cells was investigated. [3H]BIBP3226 reversibly binds to neuropeptide Y receptors of the Y1 subtype expressed in SK-N-MC cells with a KD of 2.1 +/- 0.3 nM (mean +/- S.E.M., n = 3) and a Bmax of 58,400 +/- 1100 sites/cell. Non-specific binding did not exceed 30% of the total radioactivity bound at KD. In competition experiments [3H]BIBP3226 is concentration-dependently displaced by neuropeptide Y and its peptide analogues with an affinity pattern neuropeptide Y = [Leu31, Pro34]neuropeptide Y >> neuropeptide Y-(18-36). This rank order of potencies is consistent with the interaction of [3H]BIBP3226 with neuropeptide Y receptors of the Y1 subtype. Therefore, [3H]BIBP3226 can be used as selective ligand to study neuropeptide Y Y1 receptors.