Study of the N-terminal part of peptidic selective NPFF(2) agonists

Neuropeptide FF (NPFF) has been shown to act as an endogenous anti-analgesic peptide. In this paper, several peptide analogs of the selective ligand dNP(NMe)AFLFQPQRF-NH(2) modified in the putative address segment, were designed to be selective NPFF(2) receptor probes, synthesized and assayed. One peptide dA(NMe)AAFLFQPQRF-NH(2) displays a very high affinity for NPFF(2) receptors transfected in CHO cells, and a high selectivity versus NPFF(1) receptors. The exact residues carried in the N-terminal part of the ligands are not decisive to obtain a high affinity only the length of the peptide in itself seems important to create selectivity.