title: [3H]diprenorphine binding to kappa-sites in guinea-pig and rat brain: evidence for apparent heterogeneity.
abstract: The binding of the unselective opioid antagonist [3H]diprenorphine to homogenates prepared from rat brain and from guinea-pig brain and cerebellum has been studied in HEPES buffer containing 10 mM Mg2+ ions. Sequential displacement of bound [3H]diprenorphine by ligands with selectivity for mu-, delta-, and kappa-opioid receptors uncovers the multiple components of binding. In the presence of cold ligands that occupy all mu-, delta-, and kappa-sites, opioid binding still remains. This binding represents 20% of total specific sites and is displaced by naloxone. The nature of these undefined opioid binding sites is discussed.
authors.affiliation: Department of Chemistry, University of Technology, Loughborough, Leicestershire, England.
authors.forename: M S
authors.initials: MS
authors.lastname: Wood
authors.forename: J R
authors.initials: JR
authors.lastname: Traynor
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D004174:Diprenorphine / Q000378:metabolism*; D006168:Guinea Pigs; D009019:Morphinans / Q000378:metabolism*; D051381:Rats; D011957:Receptors, Opioid / Q000378:metabolism*; D017473:Receptors, Opioid, kappa; D014316:Tritium
chemical_list: D009019:Morphinans; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D014316:Tritium; D004174:Diprenorphine