In vitro characterization of Ac-RYYRWK-NH(2), Ac-RYYRIK-NH(2) and [Phe1Psi(CH(2)-NH)Gly2] nociceptin(1-13)NH(2) at rat native and recombinant ORL(1) receptors.
The pharmacology of ORL(1) compounds, [Phe1Psi(CH(2)-NH)Gly2]nociceptin(1-13)NH(2) (F/GNC13), Ac-RYYRIK-NH(2) and Ac-RYYRWK-NH(2) was evaluated at rat ORL(1) receptors in frontal cortex (CTX), transfected chinese hamster ovary (CHO) cells, vas deferens (VD) and anococcygeus (AC). Ranked affinities for the inhibition of [3H]nociceptin binding to CTX and CHO's were: Ac-RYYRWK-NH(2) identical withAc-RYYRIK-NH(2) identical withnociceptin>F/GNC13>Dynorphin A>naloxone. The full agonist, nociceptin stimulated [35S]GTPgammaS binding in CTX (E(max)=174%) and CHO's (E(max)=311%); all other ORL(1) peptides acted as partial agonists with the following rank order for E(max) values: Ac-RYYRWK-NH(2) (96% (CTX), 202% (CHO))>F/GNC13 (44% (CTX), 136% (CHO)) identical withAc-RYYRIK-NH(2) (44% (CTX), 115% (CHO)). Schild analysis generated pA(2) values in CTX of 8.59 (F/GNC13) and 9.13 (Ac-RYYRIK-NH(2)). cAMP production in CHO's was inhibited by 77% (nociceptin), 58% (Ac-RYYRWK-NH(2)), 55% (F/GNC13) and 49% (Ac-RYYRIK-NH(2)). Nociceptin inhibited electrically evoked contractions in isolated tissues by 95% (VD) and 98% (AC); partial inhibition was observed with Ac-RYYRWK-NH(2) (72% (VD), 66% (AC)) and Ac-RYYRIK-NH(2) (54% (VD); 37%(AC)). Ineffective in the VD, F/GNC13 caused a small inhibition in the AC that was reversed at higher concentrations. Schild analysis gave pA(2) affinities of 7.32(VD) and 7.34(AC) for F/GNC13 and 8.69(AC) for Ac-RYYRIK-NH(2).
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Pfizer Global Research and Development, Cambridge University Forvie Site, Robinson Way, Cambridge, CB2 2QB, UK. sarah.mason@pfizer.com
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D000818:Animals; D016466:CHO Cells; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D018847:Opioid Peptides / Q000737:chemistry / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000819:agonists* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014649:Vas Deferens / Q000187:drug effects / Q000378:metabolism; D000094942:Nociceptin Receptor
C404152:CAM 6369; D009842:Oligopeptides; D018847:Opioid Peptides; D010446:Peptide Fragments; D011957:Receptors, Opioid; D011994:Recombinant Proteins; C114149:nociceptin (1-13)-NH2, Phe(1)-psi(CH2-NH)-Gly(2)-; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000242:Cyclic AMP; D000094942:Nociceptin Receptor