Biochemical evidence for orphanin FQ/nociceptin receptor heterogeneity in mouse brain Academic Article uri icon


MeSH Major

  • Brain
  • Opioid Peptides
  • Receptors, Opioid


  • A recently identified novel peptide, orphanin FQ/nociceptin (OFQ/N), is an endogenous ligand for a unique member of the cloned opioid receptor family. Saturation studies in mouse brain membranes reveal curvilinear Scatchard plots with both a higher (KD 3.8 pM, Bmax 31.6 fmol/mg protein) and a lower (KD 896 pM, Bmax 233 fmol/mg protein) affinity site in brain tissue, compared to only a single site in transfected CHO cells (KD 36 pM). Competition studies confirm the high affinity of OFQ/N for this site, but shallow Hill slopes suggest heterogeneity. Traditional opioids have poor affinity for this receptor and OFQ/N and its fragments do not label traditional opioid receptors. In brain homogenates, both OFQ/N and OFQ/N(1-11) inhibit forskolin-stimulated camp accumulation with IC50 values of 1 nM or less, an action which is readily reversed by opioid antagonists. OFQ/N(1-7) shows little activity. Together, these studies suggest the presence of heterogeneous, functionally active OFQ/N receptors in mouse brain.

publication date

  • January 13, 1997



  • Academic Article



  • eng

Digital Object Identifier (DOI)

  • 10.1006/bbrc.1996.5867

PubMed ID

  • 9016803

Additional Document Info

start page

  • 462

end page

  • 5


  • 230


  • 2