Modulation of neuropeptide FF receptors by guanine nucleotides and cations in membranes of rat brain and spinal cord

J Neurochem. 1993 May;60(5):1894-9. doi: 10.1111/j.1471-4159.1993.tb13417.x.


Using a radioligand binding assay, we examined ionic modulation and G protein coupling of neuropeptide FF (NPFF) receptors in membranes of rat brain and spinal cord. We found that NaCl (but not KCl or LiCl) and MgCl2 increased specific 125I-YLFQPQRFamide (125I-Y8Fa) binding to NPFF receptors in both tissues in a dose-dependent manner, with optimal conditions being 60 mM NaCl and 1 mM MgCl2. Guanine nucleotides dose-dependently inhibited specific 125I-Y8Fa binding to rat brain and spinal cord membranes with maximal effects of 64 +/- 6 and 71 +/- 2%, respectively. The order of potency was nonhydrolyzable GTP analogues > GTP > or = GDP >> GMP, ATP. The guanine nucleotide inhibition was observed in the absence and presence of NaCl and MgCl2. The mechanism of inhibition in spinal cord membranes appeared to be a reduction in the number of NPFF receptors; in one experiment, control KD and Bmax values were 0.068 nM and 7.2 fmol/mg of protein, respectively, and with 0.1 microM guanylylimidodiphosphate the respective values were 0.081 nM and 4.9 fmol/mg, a 32% reduction in receptor number. Similar results were obtained with guanosine 5'-O-(3-thiotriphosphate). Our data suggest that 125I-Y8Fa binding sites in rat CNS are G protein-coupled NPFF receptors regulated by GTP and cations.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Brain / metabolism*
  • Cations / pharmacology*
  • Guanine Nucleotides / pharmacology*
  • Membranes / metabolism
  • Molecular Sequence Data
  • Neuropeptides / metabolism
  • Oligopeptides / metabolism*
  • Rats
  • Receptors, Cell Surface / drug effects*
  • Receptors, Cell Surface / metabolism
  • Spinal Cord / metabolism*


  • Cations
  • Guanine Nucleotides
  • Neuropeptides
  • Oligopeptides
  • Receptors, Cell Surface
  • 3-iodotyrosyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide
  • phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide