Coexistence of kappa- and delta-opioid receptors in rat spinal cord axons

Martin W. Wessendorf, Jeromy Dooyema

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22 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)151-154
Number of pages4
JournalNeuroscience Letters
Issue number3
StatePublished - Feb 9 2001

Bibliographical note

Funding Information:
These studies were supported by PHS grants DA 09642 and DA 05466 from the National Institute on Drug Abuse.

Copyright 2017 Elsevier B.V., All rights reserved.


  • Analgesia
  • Heterodimers
  • Immunofluorescence
  • Kappa2-opioid receptor
  • Marginal zone
  • Pain
  • Primary afferents
  • Substantia gelatinosa


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