Pharmacological characterization of the cloned kappa opioid receptor as a kappa1b subtype

Josephine Lai, Shou Wu Ma, Rong Huan Zhu, Frank Porreca

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Substantial pharmacological evidence in vitro and in vivo has suggested the existence of subtypes ofthe kappa opioid receptor. Quantitative radioligand binding techniques resolved the presence of two high affinity binding sites for the, ligand [3H]U69,593 in mouse brain membranes, termed k1 and, respectively. Whereas the xu site has high affinity for fedotozine and oxymorphindole and low affinity for bremazocine and a-neoendorphin, site Alb has high affinity for bremazocine and a-neoendorphin and low affinity for fedotozine and oxymorphindole. 977 and U69,593 bind equally well at both sites. To determine the relationship between these x, receptor sub-types and the recently cloned mouse x, receptor (KOR), we examined [3H]U69,593 binding to the KOR in stably transfected cells (KORCHN-8). Competition of [3H]U69,593 binding to the KOR by bremazocine, a-neoendorphin, fedotozine and oxymorphindole resolved a single class of binding sites at which these agents had binding affinities similar to that of the site present in mousebrain. These results suggest that the cloned KOR corresponds to the k, site in mouse brain defined as.

Original languageEnglish (US)
Pages (from-to)2161-2164
Number of pages4
Issue number16
StatePublished - Oct 1994


  • Cloned kappa receptor
  • Kappa subtypes
  • Mouse brain
  • Opioid
  • Radioligand binding
  • Receptors

ASJC Scopus subject areas

  • Neuroscience(all)


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