title: Pharmacological characterization of the nociceptin/orphanin FQ receptor non peptide antagonist Compound 24.
abstract: Compound 24, 1-benzyl-N-[3-[spiroisobenzofuran-1(3H),4'-piperidin-1-yl]propyl] pyrrolidine-2-carboxamide was recently identified as a nociceptin/orphanin FQ (N/OFQ) peptide receptor (NOP) ligand. In this study, the in vitro and in vivo pharmacological profiles of Compound 24 were investigated. In vitro studies were performed measuring receptor and [(35)S]GTPgammaS binding and calcium mobilization in cells expressing the recombinant NOP receptor as well as using N/OFQ sensitive tissues. In vivo studies were conducted using the tail withdrawal assay in mice. Compound 24 produced a concentration-dependent displacement of [(3)H]N/OFQ binding to CHO(hNOP) cell membranes showing high affinity (pK(i) 9.62) and selectivity (1000 fold) over classical opioid receptors. Compound 24 antagonized with high potency the following in vitro effects of N/OFQ: stimulation of [(35)S]GTPgammaS binding in CHO(hNOP) cell membranes (pA(2) 9.98), calcium mobilization in CHO(hNOP) cells expressing the Galpha(qi5) chimeric protein (pK(B) 8.73), inhibition of electrically evoked twitches in the mouse (pA(2) 8.44) and rat (pK(B) 8.28) vas deferens, and in the guinea pig ileum (pK(B) 9.12). In electrically stimulated tissues, Compound 24 up to 1 microM did not modify the effects of classical opioid receptor agonists. Finally in vivo, in the mouse tail withdrawal assay, Compound 24 at 10 mg/kg antagonized the pronociceptive and antinociceptive effects of 1 nmol N/OFQ given supraspinally and spinally, respectively. Under the same experimental conditions Compound 24 did not affect the antinociceptive action of 3 nmol endomorphin-1 injected intrathecally. The present study demonstrated that Compound 24 is a pure, competitive, and highly potent non-peptide NOP receptor selective antagonist.
authors.affiliation: Department Experimental and Clinical Medicine, University of Ferrara, Ferrara, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Fischetti
authors.forename: Valeria
authors.initials: V
authors.lastname: Camarda
authors.forename: Anna
authors.initials: A
authors.lastname: Rizzi
authors.forename: Michela
authors.initials: M
authors.lastname: Pelà
authors.forename: Claudio
authors.initials: C
authors.lastname: Trapella
authors.forename: Remo
authors.initials: R
authors.lastname: Guerrini
authors.forename: John
authors.initials: J
authors.lastname: McDonald
authors.forename: David G
authors.initials: DG
authors.lastname: Lambert
authors.forename: Severo
authors.initials: S
authors.lastname: Salvadori
authors.forename: Domenico
authors.initials: D
authors.lastname: Regoli
authors.forename: Girolamo
authors.initials: G
authors.lastname: Calo'
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D004558:Electric Stimulation; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000737:chemistry / Q000378:metabolism; D008024:Ligands; D008239:Lysine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D051379:Mice; D009292:Narcotic Antagonists; D010455:Peptides / Q000737:chemistry; D011957:Receptors, Opioid / Q000378:metabolism; D013460:Sulfur Isotopes / Q000737:chemistry; D000094942:Nociceptin Receptor
chemical_list: D008024:Ligands; C472367:N-dodecyl-L-lysine amide; D009292:Narcotic Antagonists; D010455:Peptides; D011957:Receptors, Opioid; D013460:Sulfur Isotopes; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D008239:Lysine; D002118:Calcium; D000094942:Nociceptin Receptor