[3H]diprenorphine binding to kappa-sites in guinea-pig and rat brain: evidence for apparent heterogeneity

J Neurochem. 1989 Jul;53(1):173-8. doi: 10.1111/j.1471-4159.1989.tb07310.x.


The binding of the unselective opioid antagonist [3H]diprenorphine to homogenates prepared from rat brain and from guinea-pig brain and cerebellum has been studied in HEPES buffer containing 10 mM Mg2+ ions. Sequential displacement of bound [3H]diprenorphine by ligands with selectivity for mu-, delta-, and kappa-opioid receptors uncovers the multiple components of binding. In the presence of cold ligands that occupy all mu-, delta-, and kappa-sites, opioid binding still remains. This binding represents 20% of total specific sites and is displaced by naloxone. The nature of these undefined opioid binding sites is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Binding, Competitive
  • Brain / metabolism*
  • Diprenorphine / metabolism*
  • Guinea Pigs
  • Morphinans / metabolism*
  • Rats
  • Receptors, Opioid / metabolism*
  • Receptors, Opioid, kappa
  • Tritium


  • Morphinans
  • Receptors, Opioid
  • Receptors, Opioid, kappa
  • Tritium
  • Diprenorphine