title: Opioid receptors on peripheral sensory axons.
abstract: Opioid receptors have been demonstrated by light microscopic techniques in fine cutaneous nerves in naive animals. The present study extends these findings by showing that 29 and 38% of unmyelinated cutaneous sensory axons can be immunostained for mu- or delta-opioid receptors respectively. Local cutaneous injection of DAMGO, a mu-opioid ligand, ameliorates the nociceptive behaviors caused by local cutaneous injection of glutamate, a purely nociceptive chemical stimulus showing that the mu-receptors are functional. By contrast the delta-opioid ligand [2-D-penicillamine, 5-D-penicillamine]enkephalin (DPDPE) had no effect on these behaviors. These findings indicate a wider function for opioid receptors in naive animals than previously envisioned.
authors.affiliation: Department of Anatomy and Neuroscience, Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77555-1069, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Coggeshall
authors.forename: S
authors.initials: S
authors.lastname: Zhou
authors.forename: S M
authors.initials: SM
authors.lastname: Carlton
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000494:pharmacology; D007150:Immunohistochemistry; D007249:Inflammation / Q000473:pathology; D008297:Male; D009292:Narcotic Antagonists; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D017933:Peripheral Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011957:Receptors, Opioid / Q000819:agonists / Q000378:metabolism*; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000037:antagonists & inhibitors; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000037:antagonists & inhibitors; D017480:Receptors, sigma / Q000819:agonists / Q000037:antagonists & inhibitors
chemical_list: D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D017480:Receptors, sigma; D018698:Glutamic Acid