title: Evidence that dynorphin-(1-13) acts as an agonist on opioid kappa-receptors.
abstract: The study concerned the opioid-receptor subtype on which dynorphin-(1-13) acts in in vitro isolated preparations. The potency of dynorphin-(1-13) relative to that of ethylketocyclazocine (Mr 2266), a representative kappa-receptor agonist, in inhibiting the electrically evoked contractions of the guinea-pig ileum was found to be similar to that found with either mouse was deferens or rabbit ileum. Moreover, Mr 2266 was found to be several-fold more effective than naloxone to antagonize the agonist actions of both kappa-receptor agonists such as ethylketocyclazocine, ketocyclazocine and bremazocine, and dynorphin-(1-13) either in the guinea-pig ileum, mouse vas deferens, or in rabbit ileum. Additionally, dynorphin-(1-13) was found to have a significant inhibitory action on the rabbit vas deferens which had been shown to contain kappa-receptors exclusively. The data indicate that dynorphin-(1-13) acts as an endogenous agonist on kappa-receptors.
mesh_terms: D000818:Animals; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000494:pharmacology; D004399:Dynorphins; D004558:Electric Stimulation; D004723:Endorphins / Q000494:pharmacology*; D016314:Ethylketocyclazocine; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D009270:Naloxone / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*; D017473:Receptors, Opioid, kappa; D014649:Vas Deferens / Q000187:drug effects
chemical_list: D004723:Endorphins; D010446:Peptide Fragments; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D009270:Naloxone; D016314:Ethylketocyclazocine; C026843:dynorphin (1-13); D004399:Dynorphins; D003496:Cyclazocine