Characterisation of the non-peptide nociceptin receptor agonist, Ro64-6198 in Chinese hamster ovary cells expressing recombinant human nociceptin receptors.

摘要

Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the opioid receptor-like receptor or nociceptin receptor (NOP). We have compared a novel non-peptide NOP agonist Ro64-6198 with N/OFQ in a series of GTPgamma35S binding and inhibition of forskolin stimulated cAMP formation assays. GTPgamma35S binding assays were performed in membranes prepared from Chinese hamster ovary cells expressing the recombinant human NOP (CHOhNOP). cAMP inhibition studies were performed in whole CHOhNOP cells. Both Ro64-6198 and N/OFQ stimulated GTPgamma35S binding with pEC50 values(95%CL) of 7.61(0.18) and 8.58(0.21) respectively. Both Ro64-6198 and N/OFQ inhibited cAMP formation with pEC50 values of 8.45(0.9) and 9.28(028) respectively. In each assay Ro64-6198 and N/OFQ were full agonists. Ro64-6198 stimulation of GTPgamma35S binding and inhibition of cAMP formation was competitively antagonised by the NOP antagonists [Nphe1]NC(1 - 13)NH2 (10microM), J-113397 (100nM) and III-BTD (1microM) with pKB values of 7.04(0.34) and 6.29(0.10), 8.65(0.34) and 7.90(0.30) and 7.59(0.22) and 7.60(0.22) respectively. Despite the slightly reduced potency of Ro64-6198 compared with N/OFQ, by virtue of high selectivity and relative metabolic stability this molecule will be of considerable use in studies of the actions of the NOP.