Characterization of [3H]naltrindole binding to delta opioid receptors in rat brain

Mark S. Yamamura, Robert Horvath, Geza Toth, Ferenc Otvos, Ewa Malatynska, Richard J. Knapp, Frank Porreca, Victor J. Hruby, Henry I. Yamamura

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55 Scopus citations


[3H]Naltrindole binding characteristics were determined using homogenized rat brain tissue. Saturation binding studies at 25°C measured an equilibrium dissociation constant (Kd) value of 37.0 ± 3.0 pM and a receptor density (Bmax) value of 63.4 ± 2.0 fmol/mg protein. Association binding studies showed that equilibrium was reached within 90 min at a radioligand concentration of 30 pM. Naltrindole, as well as the ligands selective for delta (δ) opioid receptors, such as pCI-DPDPE and Deltorphin II inhibited [3H]naltrindole binding with nanomolar IC50 values. Ligands selective for mu (μ) and kappa (κ) opioid receptors were only effective inhibiting [3H]naltrindole binding at micromolar concentrations. From these data, we conclude that [3H]naltrindole is a high affinity, selective radioligand for delta opioid receptors.

Original languageEnglish (US)
Pages (from-to)PL119-PL124
JournalLife Sciences
Issue number16
StatePublished - 1992

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)


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