title: Rat central ORL-1 receptor uncouples from adenylyl cyclase during membrane preparation.
abstract: Nociceptin/orphanin FQ is the endogenous agonist of the orphan receptor ORL-1. In this study, we sought to examine any possible regional differences of nociceptin binding using [125I]Tyr14-nociceptin, and of agonist induced inhibition of cAMP formation in membranes prepared from cerebrocortex, cerebellum and brainstem. The binding of [125I]Tyr14-nociceptin was concentration-dependent and saturable, with Bmax and pKd (pM) values of 179.7+/-15.3 fmol/mg protein and 10.26+/-0.09 (60.0), 12.4+/-1.8 fmol/mg protein and 10.44+/-0.07 (37.0), 52.3+/-0.8 fmol/mg protein and 10.16+/-0.08 (74.0) in cerebrocortical, cerebella and brainstem membranes, respectively. In all preparations, nociceptin up to 1 microM failed to inhibit basal and forskolin stimulated cAMP formation. In all tissues forskolin stimulated and nabilone (acting at the central cannabinoid receptor) inhibited cAMP formation. Collectively these data report regional differences in ORL-1 receptor expression and that these receptors uncouple during membrane preparation.
authors.affiliation: University Department of Anaesthesia, Leicester Royal Infirmary, UK.
authors.forename: H
authors.initials: H
authors.lastname: Okawa
authors.forename: R A
authors.initials: RA
authors.lastname: Hirst
authors.forename: D
authors.initials: D
authors.lastname: Smart
authors.forename: A T
authors.initials: AT
authors.lastname: McKnight
authors.forename: D G
authors.initials: DG
authors.lastname: Lambert
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000378:metabolism; D002186:Cannabinoids / Q000037:antagonists & inhibitors; D002462:Cell Membrane / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis*; D013759:Dronabinol / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D007457:Iodine Radioisotopes; D018847:Opioid Peptides / Q000493:pharmacokinetics*; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011957:Receptors, Opioid / Q000819:agonists / Q000378:metabolism*; D000077285:Rimonabant; D000094942:Nociceptin Receptor; D000097629:Nociceptin
chemical_list: D002186:Cannabinoids; D005576:Colforsin; D000242:Cyclic AMP; D013759:Dronabinol; D007457:Iodine Radioisotopes; D018847:Opioid Peptides; D010880:Piperidines; D011720:Pyrazoles; D011957:Receptors, Opioid; D000077285:Rimonabant; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C011941:nabilone; C000722285:Oprl1 protein, rat