Opiate receptor binding profile in the rabbit cerebellum and brain membranes.
The equilibrium dissociation constants (Kd) and maximal binding capacities of tritiated dihydromorphine (DHM), [D-Ala2,D-Leu5]enkephalin (DADLE), ethylketocyclazocine (EKC) and human beta-endorphin (beta-EP) in rabbit cerebellum and brain membranes have been investigated. Binding of tritiated DHM and DADLE was adequately described by a single affinity class of binding sites, while that of EKC required two affinity sites. Binding of tritiated beta-EP was also consistent with a single affinity class of binding sites by Scatchard analysis, but inhibition of the binding with type selective opiate receptor ligands revealed multiple sites. Sequential displacement of a broad spectrum opiate ligand, diprenorphine (DIP), by type selective ligands showed that cerebellum membranes are relatively rich in mu (40%) and deficient in K (12%) binding sites, while brain membranes are relatively rich in K (32%) and deficient in mu (12%) binding sites. beta-EP displaces 88 and 73% of tritiated DIP from cerebellum and brain membranes, respectively, suggesting multiple sites of beta-EP binding.
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D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism*; D003080:Cold Temperature; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000378:metabolism; D004090:Dihydromorphine / Q000378:metabolism; D004723:Endorphins / Q000378:metabolism; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000378:metabolism; D016308:Enkephalin, Leucine-2-Alanine; D016314:Ethylketocyclazocine; D066298:In Vitro Techniques; D008297:Male; D011817:Rabbits; D011957:Receptors, Opioid / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology; D014316:Tritium; D001615:beta-Endorphin
D004723:Endorphins; D011957:Receptors, Opioid; D014316:Tritium; D016314:Ethylketocyclazocine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; D016308:Enkephalin, Leucine-2-Alanine; D012964:Sodium; D004090:Dihydromorphine; D003496:Cyclazocine