Pharmacological Characterization of the Nociceptin/Orphanin FQ Receptor Antagonist SB-612111 [(–)-cis-1-Methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol]: In Vitro Studies

  1. Barbara Spagnolo,
  2. Giacomo Carrà,
  3. Martina Fantin,
  4. Carmela Fischetti,
  5. Chris Hebbes,
  6. John McDonald,
  7. Timothy A. Barnes,
  8. Anna Rizzi,
  9. Claudio Trapella,
  10. Giulia Fanton,
  11. Michele Morari,
  12. Dave G. Lambert,
  13. Domenico Regoli and
  14. Girolamo Calò
  1. Department of Experimental and Clinical Medicine, Section of Pharmacology and Istituto Nazionale di Neuroscience (B.S., G.C., M.F., C.F., A.R., M.M., D.R., G.C.) and Department of Pharmaceutical Science and Biotechnology Center (C.T., G.F.) University of Ferrara, Ferrara, Italy; and Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom (C.H., J.M., T.A.B., D.G.L.)
  1. Address correspondence to:
    Dr. Girolamo Calò, Department of Experimental and Clinical Medicine, Section of Pharmacology, via Fossato di Mortara 19, 44100 Ferrara, Italy. E-mail: g.calo{at}unife.it

Abstract

The compound SB-612111 [(–)-cis-1-methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol] was recently identified as a selective antagonist for the nociceptin/orphanin FQ (N/OFQ) peptide receptor (NOP). In the present study, the in vitro pharmacological profile of SB-612111 at human recombinant NOP receptors expressed in Chinese hamster ovary (CHO) cells [receptor binding, guanosine 5′-O-(3-[35S]thio)triphosphate (GTPγ[35S]) binding, and cAMP level experiments] as well as at native NOP receptors expressed in peripheral (mouse and rat vas deferens, guinea pig ileum) and central (mouse cerebral cortex synaptosomes releasing [3H]5-HT) preparations was evaluated and compared with that of the standard nonpeptide antagonist (±)J-113397 [(±)-trans-1-[1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one]. SB-612111 produced a concentration-dependent displacement of [3H]N/OFQ binding to CHOhNOP cell membranes, showing higher affinity and NOP selectivity over classical opioid receptors than (±)J-113397. SB-612111 and (±)J-113397 competitively antagonized the effects of N/OFQ on GTPγ[35S] binding in CHOhNOP cell membranes (pKB, 9.70 and 8.71, respectively) and on cAMP accumulation in CHOhNOP cells (pKB, 8.63 and 7.95, respectively), being per se inactive. In isolated peripheral tissues of mice, rats, and guinea pigs and in mouse cerebral cortex synaptosomes preloaded with [3H]5-HT, SB-612111 competitively antagonized the inhibitory effects of N/OFQ, with pA2 values in the range of 8.20 to 8.50. In parallel experiments, (±)J-113397 was found to be 2- to 9-fold less potent than SB-612111. In the electrically stimulated tissues, 1 μM SB-612111 did not modify the effects of classical opioid receptor agonists. In conclusion, the results of the present study demonstrated that SB-612111 is among the most potent and NOP-selective nonpeptide antagonists identified to date.

Footnotes

  • This work was supported by the University of Ferrara (Fondi di Ateneo per la Ricerca Scientifica Grant to G.C.), by the Italian Ministry of University (Programmi di Recerca di Rilevante Interesse Nazionale 2006 Grant to D.R.), and by the National Institutes of Health (collaborative Grant RO1HL71212 to D.R.).

  • Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.

  • doi:10.1124/jpet.106.116764.

  • ABBREVIATIONS: N/OFQ, nociceptin/orphanin FQ; NOP, nociceptin/orphanin FQ peptide; (±)J-113397, (±)-trans-1-[1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one; GTPγ[35S], 5′-O-(3-[35S]thio)triphosphate; SB-612111, (–)-cis-1-methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol; CHO, Chinese hamster ovary; MOP, μ-opioid peptide; DOP, δ-opioid peptide; KOP, κ-opioid peptide; BSA, bovine serum albumin.

    • Received November 6, 2006.
    • Accepted February 27, 2007.
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  1. Published online before print February 28, 2007, doi: 10.1124/jpet.106.116764 JPET June 2007 vol. 321 no. 3 961-967
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