title: Coexistence of kappa- and delta-opioid receptors in rat spinal cord axons.
abstract: It has been found that heterodimers of kappa- and delta-opioid receptors can occur in vitro, but it has been unclear whether they also occur in intact animals. In the present study we examined whether kappa-delta heterodimers might occur in vivo by staining for these receptors with two-color fluorescence immunocytochemistry. Sections of rat spinal cord were double-stained using rabbit anti-kappa opioid receptor combined with rat anti-delta-opioid receptor. It was found that axons in the superficial dorsal horn of the spinal cord were double-labeled. In addition, structures within axonal varicosities were sometimes double-labeled. We conclude that single axons, and single structures within axons, express both kappa- and delta-opioid receptors. These observations are consistent with heterodimers of these receptors existing in vivo.
authors.affiliation: Department of Neuroscience, University of Minnesota, 6-145 Jackson Hall, 321 Church Street S.E., Minneapolis MN 55455, USA. martinw@med.umn.edu
authors.forename: M W
authors.initials: MW
authors.lastname: Wessendorf
authors.forename: J
authors.initials: J
authors.lastname: Dooyema
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000737:chemistry*; D005455:Fluorescent Antibody Technique; D008297:Male; D008969:Molecular Sequence Data; D009475:Neurons, Afferent / Q000737:chemistry / Q000166:cytology; D010146:Pain / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017465:Receptors, Opioid, delta / Q000032:analysis* / Q000737:chemistry; D017473:Receptors, Opioid, kappa / Q000032:analysis* / Q000737:chemistry; D013376:Substantia Gelatinosa / Q000737:chemistry* / Q000166:cytology
chemical_list: D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa