Effects of [(pF)Phe(4)]nociceptin/orphanin FQ-(1-13)NH(2) on GTPgamma(35)S binding and cAMP formation in Chinese hamster ovary cells expressing the human nociceptin/orphanin FQ receptor.
Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the N/OFQ receptor (NOP). In this study using Chinese hamster ovary (CHO) cells expressing the human NOP (CHO(hNOP)) and GTPgamma(35)S binding and cAMP inhibition assays, we have characterised a novel N/OFQ ligand, [(pF)Phe(4)]N/OFQ-(1-13)NH(2), ([(pF)Phe(4)]). [(pF)Phe(4)] was produced by insertion of a fluorine atom into the para position of the phenyl ring of Phe(4) of the truncated N/OFQ peptide N/OFQ-(1-13)NH(2). In CHO(hNOP) membranes [(pF)Phe(4)] and N/OFQ-(1-13)NH(2) stimulated GTPgamma35S binding with pEC(50) (mean+/-S.E.M.) values of 9.55+/-0.01 and 8.94+/-0.5 (P<0.05), respectively. In whole CHO(hNOP) cells [(pF)Phe(4)] and N/OFQ-(1-13)NH(2) inhibited forskolin stimulated cAMP formation with pEC(50) values of 10.19+/-0.06 and 9.60+/-0.04, respectively (P<0.05). [(pF)Phe(4)] was more potent ( approximately 4 fold) than N/OFQ-(1-13)NH(2). In both assays, the effects of [(pF)Phe(4)] and N/OFQ-(1-13)NH(2) were pertussis toxin sensitive and reversed by the NOP antagonists J-113397 (pA(2)/pK(B) values 7.89-8.53) and III-BTD (pA(2)/pK(B) values 7.27-7.96). [(pF)Phe(4)] is therefore a potent full agonist at NOP receptors that will be useful as pharmacological tool for defining the role of N/OFQ-NOP system in health and disease.
McDonald
John
J
University Department of Anaesthesia, Critical Care and Pain Management, Leicester Royal Infirmary, Leicester LE1 5WW, UK.
Barnes
Timothy A
TA
Calo
Girolamo
G
Guerrini
Remo
R
Rowbotham
David J
DJ
Lambert
David G
DG
D000818:Animals; D001372:Aza Compounds / Q000494:pharmacology; D001562:Benzimidazoles / Q000494:pharmacology; D016466:CHO Cells; D002264:Carboxylic Acids / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis*; D005260:Female; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006801:Humans; D009292:Narcotic Antagonists; D018847:Opioid Peptides / Q000494:pharmacology*; D010053:Ovary / Q000166:cytology; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin
D001372:Aza Compounds; D001562:Benzimidazoles; D002264:Carboxylic Acids; D000242:Cyclic AMP; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D009292:Narcotic Antagonists; D018847:Opioid Peptides; D010649:Phenylalanine; D010880:Piperidines; D011957:Receptors, Opioid; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C470322:2-oxo-3-amino-7-thia-1-aza-bicyclo(4,3,0)nonane-9-carboxylic acid; C402921:J 113397