TY - JOUR T1 - Agonistic Effect of Buprenorphine in a Nociceptin/OFQ Receptor-Triggered Reporter Gene Assay JF - Molecular Pharmacology JO - Mol Pharmacol SP - 334 LP - 338 DO - 10.1124/mol.56.2.334 VL - 56 IS - 2 AU - Stephan Wnendt AU - Thomas Krüger AU - Elke Janocha AU - Dieter Hildebrandt AU - Werner Englberger Y1 - 1999/08/01 UR - http://molpharm.aspetjournals.org/content/56/2/334.abstract N2 - The role of the opioid-like receptor 1 (ORL1) and its endogenous ligand, nociceptin/orphanin FQ (N/OFQ), in nociception, anxiety, and learning remains to be defined. To allow the rapid identification of agonists and antagonists, a reporter gene assay has been established in which the ORL1 receptor is functionally linked to the cyclic AMP-dependent expression of luciferase. N/OFQ and N/OFQ1-13NH2 inhibited the forskolin-induced luciferase gene expression with IC50 values of 0.81 ± 0.5 and 0.87 ± 0.16 nM, respectively. Buprenorphine was identified as a full agonist at the ORL1 receptor with an IC50 value of 8.4 ± 2.8 nM. Fentanyl and 7-benzylidenenaltrexone displayed a weak agonistic activity. The ORL1 antagonist [Phe1Ψ(CH2-NH)Gly2]N/OFQ(1–13)NH2clearly behaved as an agonist in this assay with an IC50value of 85 ± 47 nM. Thus, there is still a need for antagonistic tool compounds that might help to elucidate the neurophysiological role of N/OFQ. ER -