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Gene Review

PNOC  -  prepronociceptin

Homo sapiens

Synonyms: OFQ, PPNOC, Prepronociceptin
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Disease relevance of PNOC

  • The results demonstrate that N/OFQ can effectively stimulate MAPK by the activation of ORL1 receptor and pertussis toxin-sensitive G proteins, and that phospholipase C, as well as protein kinase C, is critically involved in these processes [1].
  • Mu-Opioid receptors have been shown to contribute to orphanin FQ/nociceptin (OFQ/N)-mediated analgesia and hyperalgesia, indicating that both pro- and antinociceptive actions of OFQ/N are influenced by mu-opioid receptors [2].
  • The present data demonstrated that astrocyte activation and enhanced cytokine expression at the CNS had a role in eliciting behavioral hypersensitivity; the anti-nociception function of N/OFQ might be dependent on cytokines derived from astrocytes, the effects were attributable to the ORL1 receptor pathway [3].
  • This study was designed to investigate the intracellular signaling mechanism of N/OFQ in human dopaminergic neuroblastoma SH-SY5Y cells [4].
  • The effect occurs at doses that are not hyperphagic per se and is clearly selective versus the anorectic action of CRF since N/OFQ or Ro 64-6198 do not influence the anorectic effect of Escherichia coli lipopolysaccharide (LPS) [5].

Psychiatry related information on PNOC

  • 4. UFP-101 is also active in vivo where it prevented the depressant action on locomotor activity and the pronociceptive effect induced by 1 nmol N/OFQ i.c.v. in the mouse [6].
  • Many studies point toward the nociceptin/orphanin FQ (N/OFQ) and the N/OFQ peptide receptor (NOP) as targets for the development of innovative drugs for treating affective disorders [7].
  • Together, these findings suggest that N/OFQ and its receptor may represent an interesting target for pharmacological treatment of alcohol abuse [8].
  • Other possible applications of OFQ/N agonists and antagonists include treatment of depression, anorexia and rewarding aspects of drug addiction [9].
  • Also, data suggest that N/OFQ may not only promote feeding initiation, but rather its role may be to inhibit signaling responsible for inhibition of consummatory behavior [10].

High impact information on PNOC

  • This review will address the molecular biology and behavioral pharmacology of OFQ/N and its receptor [11].
  • The number and diversity of papers focused on OFQ/N1-17 at the recent meeting of the Society for Neuroscience augur an exciting future for this new peptide [12].
  • The predicted amino acid sequence of the OFQ precursor contains a putative signal peptide and one copy of the OFQ sequence flanked by pairs of basic amino acid residues [13].
  • Alanine- and D-amino acid-scanning mutagenesis revealed several residues in the amino-terminal half of OFQ which participate in both receptor binding and activation [14].
  • In addition, in cells expressing mu receptors in which the GRK-mediated phosphorylation site Ser(375) was mutated to alanine, OFQ/N treatment failed to potentiate DAMGO-induced mu receptor phosphorylation and failed to desensitize the mu receptor [15].

Chemical compound and disease context of PNOC


Biological context of PNOC

  • Agonistic effect of buprenorphine in a nociceptin/OFQ receptor-triggered reporter gene assay [18].
  • N/OFQ and N/OFQ(1-13)NH(2) inhibited the forskolin-induced luciferase gene expression with IC(50) values of 0.81 +/- 0.5 and 0.87 +/- 0.16 nM, respectively [18].
  • Previous studies have reported alternative splicing between exons 3 and 4 of the mouse OFQ/N transcript, which, upon translation, would yield precursor proteins with different C-termini [19].
  • When human embryonic kidney 293 cells stably expressing the human ORL1 receptor were pre-exposed (30 min) to either OFQ/N or Ro 64-6198, the ability of both agonists to inhibit forskolin-mediated cAMP accumulation was strongly reduced, indicating a functional desensitization of the second messenger cascade [20].
  • Interestingly, KT5720, a specific inhibitor of PKA, markedly suppressed the phosphorylation of MAPK by N/OFQ in SH-SY5Y cells [4].

Anatomical context of PNOC

  • In CHO cells, 125I-Tyr14-OFQ detected a single affinity state with an intermediate Kd value of 54 pM [21].
  • In rat brain membranes, specific, saturable binding of 125I-Tyr14-OFQ was demonstrated to be pharmacologically identical to the heterologously expressed OFQ-R [21].
  • The Spiegelmers antagonized the N/OFQ-induced GTPgammaS incorporation into cell membranes of a CHO-K1 cell line expressing the human ORL1 receptor [22].
  • When the ORL1 receptor was transiently co-expressed in COS-7 cells with the alpha-subunit of G16, nociceptin/OFQ dose-dependently stimulated the formation of inositol phosphates [23].
  • In the present study, we investigated: (1) astrocyte activation and proinflammatory cytokine expression at the lumbar spinal cord following intraplantar administration of complete Freund's adjuvant (CFA) in rats; (2) the mechanism of N/OFQ on nociception modulation, the relationship between N/OFQ and cytokines in the rat CNS in vivo and in vitro [3].

Associations of PNOC with chemical compounds

  • In cells expressing both ORL-1 (OFQR) and mu-opioid receptors, pretreatment with nociceptin decreased subsequent nociceptin (OFQ)- or DAMGO-stimulated MAP kinase activation [24].
  • In HEK 293 cells transiently expressing the ORL1 and dopamine D1 receptors, nociceptin/OFQ dose-dependently inhibited dopamine-stimulated cyclic AMP (cAMP) accumulation in a PTX-sensitive manner [23].
  • However, PTX failed to block the nociceptin/OFQ-induced inhibition of dopamine-stimulated cAMP accumulation in HEK 293 cells co-expressing the alpha-subunit of Gz [23].
  • U-73122, a phospholipase C-specific inhibitor, significantly inhibited phospholipase C activity, as well as MAPK activation stimulated by N/OFQ [1].
  • Further, (+)-5a potently stimulated GTP gamma S binding to NOP membranes (EC50 = 65 nM) and inhibited forskolin-mediated cAMP accumulation in NOP-expressing cells (EC50 = 9.1 nM) with a potency comparable to that of the natural peptide agonist N/OFQ [25].

Physical interactions of PNOC

  • These compounds were tested for binding affinity using [3H]N/OFQ binding to human ORL1 in CHO cells, and functional activity by measuring stimulation of [35S]GTPgammaS binding in CHO cell membranes [26].

Regulatory relationships of PNOC

  • Our results demonstrate for the first time the involvement of conventional PKC isozymes in OFQ/N-induced mu-ORL1 cross-talk, and represent a possible mechanism for OFQ/N-induced anti-opioid actions [27].
  • However, on re-stimulated T cells N/OFQ causes inhibition of proliferation, which could be linked with N/OFQ up-regulating CTLA-4 expression [28].
  • Inclusion of OFQ/N during chronic morphine exposure also blocked morphine-induced TH upregulation [29].
  • Taken together, these results suggest that N/OFQ independently induces the activation of CREB prior to MAPK phosphorylation, which was also modulated by PKA [4].

Other interactions of PNOC

  • Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the opioid receptor-like receptor or nociceptin receptor (NOP) [30].
  • This study shows that N/OFQ (10(-14)-10(-12) M) modulates T cell activation by up-regulating activation marker expression, e.g. CD28, leading to enhanced proliferation and modulation of TNFalpha secretion [28].
  • Pretreatment with orphanin FQ/nociceptin (OFQ/N) also upregulated GRK3 levels in both cell lines, and desensitized both receptors in BE(2)-C cells [31].
  • Here, we demonstrate for the first time a role for ERK1/2-mediated GRK2 induction in the development of tolerance to mu agonists, as well as cross-tolerance to OFQ/N [31].
  • Furthermore, chronic OFQ/N exposure increased levels of the TH gene repressor, Oct-2, irrespective of the presence or absence of morphine [29].

Analytical, diagnostic and therapeutic context of PNOC

  • In situ hybridization of rat brain slices demonstrated a regional distribution pattern of the OFQ precursor mRNA, which is distinct from that of the opioid peptide precursors [13].
  • A physiologic role for nociceptin (OFQ) activation of the ORL-1 receptor (OFQR) may be to modulate opioid-induced analgesia [24].
  • We measured the concentrations of N/OFQ in 47 microdissected areas of the central nervous system of adult human brain using radioimmunoassay (RIA) [32].
  • The receptor mRNA is likely to arise from a single gene, as determined by Southern blotting of porcine genomic DNA restriction digests using a porcine OFQ receptor cDNA probe [33].
  • In contrast, the blockade of N/OFQ signaling obtained with NOP-selective antagonists promotes antidepressant-like effects in the forced swimming and tail suspension tests [7].


  1. Nociceptin/orphanin FQ activates mitogen-activated protein kinase in Chinese hamster ovary cells expressing opioid receptor-like receptor. Lou, L.G., Zhang, Z., Ma, L., Pei, G. J. Neurochem. (1998) [Pubmed]
  2. Mu-opioid-induced desensitization of opioid receptor-like 1 and mu-opioid receptors: differential intracellular signaling determines receptor sensitivity. Mandyam, C.D., Thakker, D.R., Standifer, K.M. J. Pharmacol. Exp. Ther. (2003) [Pubmed]
  3. Regulation of proinflammatory cytokines gene expression by nociceptin/orphanin FQ in the spinal cord and the cultured astrocytes. Fu, X., Zhu, Z.H., Wang, Y.Q., Wu, G.C. Neuroscience (2007) [Pubmed]
  4. Regulation of cyclic AMP-dependent response element-binding protein (CREB) by the nociceptin/orphanin FQ in human dopaminergic SH-SY5Y cells. Kim, M.S., Cheong, Y.P., So, H.S., Lee, K.M., Son, Y., Lee, C.S., Yun, J.S., Park, R. Biochem. Biophys. Res. Commun. (2002) [Pubmed]
  5. Nociceptin/orphanin FQ acts as a functional antagonist of corticotropin-releasing factor to inhibit its anorectic effect. Ciccocioppo, R., Cippitelli, A., Economidou, D., Fedeli, A., Massi, M. Physiol. Behav. (2004) [Pubmed]
  6. [Nphe1,Arg14,Lys15]nociceptin-NH2, a novel potent and selective antagonist of the nociceptin/orphanin FQ receptor. Calo, G., Rizzi, A., Rizzi, D., Bigoni, R., Guerrini, R., Marzola, G., Marti, M., McDonald, J., Morari, M., Lambert, D.G., Salvadori, S., Regoli, D. Br. J. Pharmacol. (2002) [Pubmed]
  7. Antidepressant- and anxiolytic-like effects of nociceptin/orphanin FQ receptor ligands. Gavioli, E.C., Calo', G. Naunyn Schmiedebergs Arch. Pharmacol. (2006) [Pubmed]
  8. The nociceptin/orphanin FQ/NOP receptor system as a target for treatment of alcohol abuse: a review of recent work in alcohol-preferring rats. Ciccocioppo, R., Economidou, D., Fedeli, A., Massi, M. Physiol. Behav. (2003) [Pubmed]
  9. The Orphanin FQ / Nociceptin Receptor as a Novel Drug Target in Psychiatric Disorders. Reinscheid, R.K. CNS & neurological disorders drug targets. (2006) [Pubmed]
  10. Minireview: Characterization of influence of central nociceptin/orphanin FQ on consummatory behavior. Olszewski, P.K., Levine, A.S. Endocrinology (2004) [Pubmed]
  11. The molecular and behavioral pharmacology of the orphanin FQ/nociceptin peptide and receptor family. Mogil, J.S., Pasternak, G.W. Pharmacol. Rev. (2001) [Pubmed]
  12. Orphanin FQ/nociceptin: a role in pain and analgesia, but so much more. Darland, T., Heinricher, M.M., Grandy, D.K. Trends Neurosci. (1998) [Pubmed]
  13. Primary structure and tissue distribution of the orphanin FQ precursor. Nothacker, H.P., Reinscheid, R.K., Mansour, A., Henningsen, R.A., Ardati, A., Monsma, F.J., Watson, S.J., Civelli, O. Proc. Natl. Acad. Sci. U.S.A. (1996) [Pubmed]
  14. Structure-activity relationship studies on the novel neuropeptide orphanin FQ. Reinscheid, R.K., Ardati, A., Monsma, F.J., Civelli, O. J. Biol. Chem. (1996) [Pubmed]
  15. Orphanin FQ/nociceptin potentiates [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin-Induced mu-opioid receptor phosphorylation. Ozsoy, H.Z., Thakker, D.R., Standifer, K.M. Mol. Pharmacol. (2005) [Pubmed]
  16. Site-specific estrogen and progestin regulation of orphanin FQ/nociceptin and nociceptin opioid receptor mRNA expression in the female rat limbic hypothalamic system. Sinchak, K., Romeo, H.E., Micevych, P.E. J. Comp. Neurol. (2006) [Pubmed]
  17. Nocistatin: a novel neuropeptide encoded by the gene for the nociceptin/orphanin FQ precursor. Okuda-Ashitaka, E., Ito, S. Peptides (2000) [Pubmed]
  18. Agonistic effect of buprenorphine in a nociceptin/OFQ receptor-triggered reporter gene assay. Wnendt, S., Krüger, T., Janocha, E., Hildebrandt, D., Englberger, W. Mol. Pharmacol. (1999) [Pubmed]
  19. Differential splicing of transcripts encoding the orphanin FQ/nociceptin precursor. Arjomand, J., Evans, C.J. J. Neurochem. (2001) [Pubmed]
  20. Pharmacological characterization of the novel nonpeptide orphanin FQ/nociceptin receptor agonist Ro 64-6198: rapid and reversible desensitization of the ORL1 receptor in vitro and lack of tolerance in vivo. Dautzenberg, F.M., Wichmann, J., Higelin, J., Py-Lang, G., Kratzeisen, C., Malherbe, P., Kilpatrick, G.J., Jenck, F. J. Pharmacol. Exp. Ther. (2001) [Pubmed]
  21. Interaction of [3H]orphanin FQ and 125I-Tyr14-orphanin FQ with the orphanin FQ receptor: kinetics and modulation by cations and guanine nucleotides. Ardati, A., Henningsen, R.A., Higelin, J., Reinscheid, R.K., Civelli, O., Monsma, F.J. Mol. Pharmacol. (1997) [Pubmed]
  22. Biostable aptamers with antagonistic properties to the neuropeptide nociceptin/orphanin FQ. Faulhammer, D., Eschgfäller, B., Stark, S., Burgstaller, P., Englberger, W., Erfurth, J., Kleinjung, F., Rupp, J., Dan Vulcu, S., Schröder, W., Vonhoff, S., Nawrath, H., Gillen, C., Klussmann, S. RNA (2004) [Pubmed]
  23. Pertussis toxin-insensitive signaling of the ORL1 receptor: coupling to Gz and G16 proteins. Chan, J.S., Yung, L.Y., Lee, J.W., Wu, Y.L., Pei, G., Wong, Y.H. J. Neurochem. (1998) [Pubmed]
  24. Nociceptin (ORL-1) and mu-opioid receptors mediate mitogen-activated protein kinase activation in CHO cells through a Gi-coupled signaling pathway: evidence for distinct mechanisms of agonist-mediated desensitization. Hawes, B.E., Fried, S., Yao, X., Weig, B., Graziano, M.P. J. Neurochem. (1998) [Pubmed]
  25. Novel hexahydrospiro[piperidine-4,1'-pyrrolo[3,4-c]pyrroles]: highly selective small-molecule nociceptin/orphanin FQ receptor agonists. Kolczewski, S., Adam, G., Cesura, A.M., Jenck, F., Hennig, M., Oberhauser, T., Poli, S.M., Rössler, F., Röver, S., Wichmann, J., Dautzenberg, F.M. J. Med. Chem. (2003) [Pubmed]
  26. N-terminal modifications leading to peptide ORL1 partial agonists and antagonists. Judd, A.K., Kaushanskaya, A., Tuttle, D.J., Sanchez, A., Khroyan, T., Polgar, W., Toll, L. J. Pept. Res. (2003) [Pubmed]
  27. Orphanin FQ/nociceptin-mediated desensitization of opioid receptor-like 1 receptor and mu opioid receptors involves protein kinase C: a molecular mechanism for heterologous cross-talk. Mandyam, C.D., Thakker, D.R., Christensen, J.L., Standifer, K.M. J. Pharmacol. Exp. Ther. (2002) [Pubmed]
  28. Nociceptin/orphanin FQ modulates human T cell function in vitro. Waits, P.S., Purcell, W.M., Fulford, A.J., McLeod, J.D. J. Neuroimmunol. (2004) [Pubmed]
  29. Orphanin FQ/nociceptin blocks chronic morphine-induced tyrosine hydroxylase upregulation. Thakker, D.R., Standifer, K.M. Brain Res. Mol. Brain Res. (2002) [Pubmed]
  30. Characterisation of the non-peptide nociceptin receptor agonist, Ro64-6198 in Chinese hamster ovary cells expressing recombinant human nociceptin receptors. Hashiba, E., Lambert, D.G., Jenck, F., Wichmann, J., Smith, G. Life Sci. (2002) [Pubmed]
  31. Induction of G protein-coupled receptor kinases 2 and 3 contributes to the cross-talk between mu and ORL1 receptors following prolonged agonist exposure. Thakker, D.R., Standifer, K.M. Neuropharmacology (2002) [Pubmed]
  32. Distribution of nociceptin/orphanin FQ in adult human brain. Witta, J., Palkovits, M., Rosenberger, J., Cox, B.M. Brain Res. (2004) [Pubmed]
  33. Cloning, expression and functional role of a nociceptin/orphanin FQ receptor in the porcine gastrointestinal tract. Osinski, M.A., Pampusch, M.S., Murtaugh, M.P., Brown, D.R. Eur. J. Pharmacol. (1999) [Pubmed]
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