Pharmacological profile of NOP receptors coupled with calcium signaling via the chimeric protein G alpha qi5.
In this study, the Galpha(qi5) protein was used to force the human nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor to signal through the Ca(2+) pathway in CHO cells. [Ca(2+)](i) levels were monitored using the fluorometer FlexStation II and the Ca(2+) dye Fluo 4 AM. Concentration response curves were generated with a panel of full and partial agonists, while NOP antagonists were assessed in inhibition-response curves. The following rank order of potency of antagonists was measured: SB - 612111 > J - 113397 = Trap - 101 > or = UFP - 101 > [Nphe1]N/OF Q(1 - 13)NH2 >> naloxone, which is superimposable to literature findings. The rank order of potency of full and partial agonists is also similar to that obtained in previous studies with the exception of a panel of ligands (UFP-112, Ro 64-6198, ZP120, UFP-113) whose potency was relatively low in the Galpha(qi5)-NOP receptor calcium assay. Interestingly, these NOP ligands are characterized by slow kinetic of interaction with the NOP receptor, as demonstrated by bioassay experiments. These results demonstrated that the FlexStation II-Galpha(qi5)-NOP receptor calcium assay represents an adequate and useful screening for NOP receptor ligands, particularly for antagonists.
Camarda
Valeria
V
Department Experimental and Clinical Medicine, Section of Pharmacology and Neuroscience Center, University of Ferrara, National Institute of Neuroscience, Via Fossato di Mortara 19, 44100, Ferrara, Italy.
Fischetti
Carmela
C
Anzellotti
Nicholas
N
Molinari
Paola
P
Ambrosio
Caterina
C
Kostenis
Evi
E
Regoli
Domenico
D
Trapella
Claudio
C
Guerrini
Remo
R
Severo
Salvadori
S
Calo
Girolamo
G
D000818:Animals; D001562:Benzimidazoles / Q000378:metabolism / Q000494:pharmacology; D016466:CHO Cells; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D006801:Humans; D010880:Piperidines / Q000378:metabolism / Q000494:pharmacology; D011957:Receptors, Opioid / Q000819:agonists / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D000094942:Nociceptin Receptor
D001562:Benzimidazoles; C402921:J 113397; D010880:Piperidines; D011957:Receptors, Opioid; D011993:Recombinant Fusion Proteins; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D000094942:Nociceptin Receptor