Opioid receptors on peripheral sensory axons.
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.
Coggeshall
R E
RE
Department of Anatomy and Neuroscience, Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77555-1069, USA.
Zhou
S
S
Carlton
S M
SM
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
D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D017480:Receptors, sigma; D018698:Glutamic Acid