Evidence that endogenous enkephalins produce delta-opiate receptor mediated neuronal inhibitions in rat dorsal horn.
Kelatorphan, a full inhibitor of aminopeptidases, enkephalinase and dipeptidylaminopeptidase, enzymes which degrade the enkephalins, produced inhibitions (around 50%) of dorsal horn C fibre evoked responses in the rat, following local application. The inhibitions were reversed by the selective delta-opiate receptor antagonists ICI 174,864. Furthermore the inhibitions produced by two doses of Tyr-D-Ala-Gly-MePhe-Gly-ol (DAGO), a potent selective mu-opiate receptor agonist, were not altered in the presence of kelatorphan, so demonstrating an additive effect of the mu-agonist and the enzyme inhibitor. The inhibitions produced by the enzyme inhibitor would seem due to an increased availability of endogenous opioids, presumably the enkephalins which act via the delta-opiate receptor.
D000818:Animals; D004151:Dipeptides / Q000494:pharmacology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D004745:Enkephalins / Q000494:pharmacology / Q000502:physiology*; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition; D051381:Rats; D011957:Receptors, Opioid / Q000502:physiology*; D017465:Receptors, Opioid, delta; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*
D004151:Dipeptides; D004745:Enkephalins; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C042591:kelatorphan; D004743:Enkephalin, Leucine; C040643:N,N-diallyl-tyrosyl-alpha-aminoisobutyric acid-phenylalanyl-leucine