Receptor preference of dynorphin A fragments in the mouse vas deferens determined by different techniques.
The opioid receptor preference of dynorphin A fragments, particularly of dynorphin A-(1-8) (DYN 8), has been evaluated in the mouse vas deferens by means of cross-tolerance studies, by their sensitivity to naloxone antagonism and by the use of the irreversible narcotic antagonist beta-funaltrexamine. The tolerance studies revealed kappa receptor activity for the longer fragments and delta activity for the shorter fragments. DYN 8 displayed kappa as well as delta activity, whereas no interaction with mu receptors was observed. The naloxone sensitivity of dynorphin A and its fragments was low with the exception of DYN 8, that displayed an intermediate sensitivity. There was no indication that this intermediate value for DYN 8 was due to an interaction with mu receptors. This conclusion was strengthened in experiments using beta-funaltrexamine. The kappa and delta activity of DYN 8 does not explain the intermediate sensitivity to naloxone. It is proposed that DYN 8 may interact in the mouse vas deferens with a different opioid receptor than the classical mu, kappa- and delta-type.
D000818:Animals; D004361:Drug Tolerance; D004399:Dynorphins; D004723:Endorphins / Q000378:metabolism*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D005283:Fentanyl / Q000494:pharmacology; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism*; D011957:Receptors, Opioid / Q000378:metabolism*; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D014649:Vas Deferens / Q000378:metabolism*
D004723:Endorphins; D010446:Peptide Fragments; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D009270:Naloxone; D004743:Enkephalin, Leucine; D009271:Naltrexone; D016308:Enkephalin, Leucine-2-Alanine; C024524:beta-funaltrexamine; D004399:Dynorphins; C026770:dynorphin (1-8); D005283:Fentanyl