AUTORADIOGRAPHIC CHARACTERIZATION OF RAT SPINAL NEUROPEPTIDE FF RECEPTORS BY USING [I-125] [D.TYR(1), (NME)PHE(3)]NPFF

The binding properties of neuropeptide FF (NPFF) receptors were invest igated in different laminae of the rat spinal cord by using quantitati ve autoradiography and [I-125][D.Tyr(1), (NMe)Phe(3)]NPFF as radioliga nd. In the superficial layers, the specific binding of [I-125][D.Tyr(1 ), (NMe)Phe(3)]NPFF was time-dependent, reversible, and saturable (K-D = 0.1 nM). Preincubation of spinal sections increased the maximal num ber of [I-125][D.Tyr(1), (NMe)Phe(3)]NPFF binding sites. Bestatin, an inhibitor of aminopeptidases, increased significantly the apparent aff inity of NPFF. Optimal binding of [I-125][D.Tyr(1), (NMe)Phe(3)NPFF wa s observed in the presence of 120 mM NaCl in all laminae of the spinal cord. No significant differences were noted in the salt dependence in laminae I-II, IV-V, and X, and the pharmacological profile of [I-125] [D.Tyr(1), (NMe)Phe(3)]NPFF binding was similar in each laminae. These results do not support the existence of NPFF receptors subtypes diffe rentially localized in different area of the spinal cord. Our data rev eal the effects of tissue treatments on binding characteristics of NPF F receptors and indicate that [I-125][D.Tyr(1), (NMe)Phe(3)]NPFF is a useful radioactive probe for the characterization of NPFF receptors in discrete brain areas. Copyright (C) 1997 Elsevier Science Inc.