Evidence for functional delta-opiate receptors in the rat intestine.
The selective delta-opiate agonists D-Ser2, Leu5, Thr6-enkephalin (DSLET), D-Ala2, D-Leu5-enkephalin and D-Pen2, D-Pen5-enkephalin caused inhibition of the cholinergic contraction produced by transmural stimulation of the rat isolated jejunum. Dynorphin A, which is an agonist at both kappa- and delta-opioid receptors also inhibited the cholinergic contraction, as did leu- and met-enkephalin. The selective mu-receptor agonist D-Ala2-NMe-Phe4, Gly-ol5-enkephalin was the least potent of all peptides tested. In general, the order of potency of the peptides was similar to that reported for the delta-receptor-rich mouse vas deferens with potency values similar to those recorded previously for the hamster vas deferens. The selective delta-opioid antagonist naltrindole caused parallel shifts to the concentration-effect curve to DSLET giving a pA2 value of 10.15. The results indicate that the previously identified delta-binding sites in the rat jejunum may correspond to functional delta-opiate receptors involved in attenuating acetylcholine release.
Hancock
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Unit of Addictive Drug Research, School of Pharmaceutical Pharmacology, Victorian College of Pharmacy, Monash University, Parkville, Australia.
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D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D006224:Cricetinae; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*
D017465:Receptors, Opioid, delta; D004743:Enkephalin, Leucine; D009271:Naltrexone; D016308:Enkephalin, Leucine-2-Alanine; C034318:enkephalin, Ser(2), Leu(5), Thr(6)-; C055382:naltrindole; D000109:Acetylcholine