Pharmacological characterization of human NPFF 1 and NPFF 2 receptors expressed in CHO cells by using NPY Y 1 receptor antagonists

Abstract

Neuropeptide FF (NPFF) belongs to an opioid-modulatory system including two precursors (pro-NPFF A and pro-NPFF B) and two G-protein coupled receptors (NPFF 1 and NPFF 2). The pharmacological and functional profiles of human NPFF 1 and NPFF 2 receptors expressed in Chinese hamster ovary (CHO) cells were compared by determining the affinity of several peptides derived from both NPFF precursors and by measuring their abilities to inhibit forskolin-induced cAMP accumulation. Each NPFF receptor recognizes peptides from both precursors with nanomolar affinities, however, with a slight preference of pro-NPFF A peptides for NPFF 2 receptors and of pro-NPFF B peptides for NPFF 1 receptors. BIBP3226 (( R)- N 2-(diphenylacetyl)- N-[(4-hydroxyphenyl)-methyl]-argininamide) and BIBO3304 (( R)- N 2-(diphenylacetyl)- N-[4-(aminocarbonylaminomethyl)-benzyl]-argininamide trifluoroacetate), two selective neuropeptide Y (NPY) Y 1 receptor antagonists, display relative high affinities for NPFF receptors and exhibit antagonist properties towards hNPFF 1 receptors. The structural determinants responsible for binding of these molecules to NPFF receptors were investigated and led to the synthesis of hNPFF 1 receptor antagonists with affinities from 40 to 80 nM. Our results demonstrate differences in pharmacological characteristics between NPFF 1 and NPFF 2 receptors and the feasibility of subtype-selective antagonists.