title: Inverse agonist properties of N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl (SR141716A) and 1-(2-chlorophenyl)-4-cyano-5-(4-methoxyphenyl)-1H-pyrazole-3-carboxyl ic acid phenylamide (CP-272871) for the CB(1) cannabinoid receptor.
abstract: Two subtypes of cannabinoid receptors are currently recognized, CB(1), found in brain and neuronal cells, and CB(2), found in spleen and immune cells. We have characterized 1-(2-chlorophenyl)-4-cyano-5-(4-methoxyphenyl)-1H-pyrazole-3-carboxyl ic acid phenylamide (CP-272871) as a novel aryl pyrazole antagonist for the CB(1) receptor. CP-272871 competed for binding of the cannabinoid agonist (3)H-labeled (-)-3-[2-hydroxy-4-(1, 1-dimethylheptyl)-phenyl]-4-[3-hydroxypropyl]cyclohexan-1-ol ([(3)H]CP-55940) at the CB(1) receptor in rat brain membranes with a K(d) value 20-fold greater than that of N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2, 4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide HCl (SR141716A). CP-272871 also competed for binding with the aminoalkylindole agonist (3)H-labeled (R)-(+)-[2, 3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrrolo[1,2,3-de]1, 4-benzoxazin-6-yl](1-naphthyl)methanone ([(3)H]WIN-55212-2), as well as the aryl pyrazole antagonist [(3)H]SR141716A. Inverse agonist as well as antagonist properties were observed for both SR141716A and CP-272871 in signal transduction assays in biological preparations in which the CB(1) receptor is endogenously expressed. SR141716A augmented secretin-stimulated cyclic AMP (cAMP) accumulation in intact N18TG2 neuroblastoma cells, and this response was reversed by the agonist desacetyllevonantradol. CP-272871 antagonized desacetyllevonantradol-mediated inhibition of adenylyl cyclase in N18TG2 membranes, and increased adenylyl cyclase activity in the absence of agonist. SR141716A and CP-272871 antagonized desacetyllevonantradol-stimulated (35)S-labeled guanosine-5'-O-(gamma-thio)-triphosphate ([(35)S]GTPgammaS) binding to brain membrane G-proteins, and decreased basal [(35)S]GTPgammaS binding to G-proteins. K(+) enhanced CP-272871 and SR141716A inverse agonist activity compared with Na(+) or NMDG(+) in the assay. These results demonstrated that the aryl pyrazoles SR141716A and CP-272871 behave as antagonists and as inverse agonists in G-protein-mediated signal transduction in preparations of endogenously expressed CB(1) receptors.
authors.affiliation: Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Meschler
authors.forename: D M
authors.initials: DM
authors.lastname: Kraichely
authors.forename: G H
authors.initials: GH
authors.lastname: Wilken
authors.forename: A C
authors.initials: AC
authors.lastname: Howlett
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000494:pharmacology*; D016466:CHO Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D010880:Piperidines / Q000494:pharmacology*; D011720:Pyrazoles / Q000737:chemistry / Q000494:pharmacology*; D011869:Radioligand Assay; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000077285:Rimonabant; D014162:Transfection
chemical_list: D001555:Benzene Derivatives; C415090:CP 272871; C469526:Cnr2 protein, rat; D010880:Piperidines; D011720:Pyrazoles; D043885:Receptor, Cannabinoid, CB2; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D000077285:Rimonabant