Electrophysiological studies on the spinal effects of dermorphin, an endogenous mu-opioid agonist.
The intrathecal administration of dermorphin, an endogenous heptopeptide first discovered in amphibia, produces dose-dependent selective inhibitions of C fibre-evoked responses in rat dorsal horn nociceptive neurones (ED50 0.11 micrograms). Naloxone (10 micrograms) but not ICI 174,864 (125 micrograms) antagonised the effects of the peptide. A beta-fibre-evoked activity was relatively unaffected. Thus dermorphin can profoundly inhibit nociceptive afferent input in the spinal cord, and in this preparation is more potent (approximately 40X) than morphine.
Sullivan
A F
AF
Department of Pharmacology, University College London, U.K.
Dickenson
A H
AH
D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D005071:Evoked Potentials / Q000187:drug effects; D007700:Kinetics; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009842:Oligopeptides / Q000494:pharmacology*; D018847:Opioid Peptides; D010146:Pain / Q000503:physiopathology; D010812:Physical Stimulation; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000502:physiology*; D017450:Receptors, Opioid, mu; D012016:Reference Values; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*
D000701:Analgesics, Opioid; D009842:Oligopeptides; D018847:Opioid Peptides; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; C030058:dermorphin