title: Dynorphin is a specific endogenous ligand of the kappa opioid receptor.
abstract: In the guinea pig ileum myenteric plexus--longitudinal muscle preparation, dynorphin-(1--13) and the prototypical kappa agonist ethylketocyclazocine had equally poor sensitivity to naloxone antagonism and showed selective cross protection in receptor inactivation experiments with the alkylating antagonist beta-chlornaltrexamine. In binding assays with membranes from guinea pig brain, ethylketocyclazocine and dynorphin-(1--13) amide were more potent in displacing tritium-labeled ethylketocyclazocine than in displacing typical mu and delta opioid receptor ligands. In the two preparations studied, the dynorphin receptor appears to be the same as the kappa opioid receptor.
mesh_terms: D000701:Analgesics, Opioid / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000378:metabolism; D004399:Dynorphins; D004723:Endorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine; D004745:Enkephalins / Q000378:metabolism; D016314:Ethylketocyclazocine; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008024:Ligands; D009022:Morphine Derivatives / Q000378:metabolism; D009197:Myenteric Plexus / Q000378:metabolism; D009270:Naloxone / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D000701:Analgesics, Opioid; D004723:Endorphins; D004745:Enkephalins; D008024:Ligands; D009022:Morphine Derivatives; D010446:Peptide Fragments; D011957:Receptors, Opioid; D009270:Naloxone; D016314:Ethylketocyclazocine; D004743:Enkephalin, Leucine; C026843:dynorphin (1-13); D004399:Dynorphins; D003496:Cyclazocine; C010616:normorphine