title: Characterization of [3H]naltrindole binding to delta opioid receptors in rat brain.
abstract: [3H]Naltrindole binding characteristics were determined using homogenized rat brain tissue. Saturation binding studies at 25 degrees 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 (delta) opioid receptors, such as pCI-DPDPE and Deltorphin II inhibited [3H]naltrindole binding with nanomolar IC50 values. Ligands selective for mu (mu) and kappa (kappa) opioid receptors were only effective in 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.
authors.affiliation: Department of Pharmacology, University of Arizona, College of Medicine, Tucson 85724.
authors.forename: M S
authors.initials: MS
authors.lastname: Yamamura
authors.forename: R
authors.initials: R
authors.lastname: Horvath
authors.forename: G
authors.initials: G
authors.lastname: Toth
authors.forename: F
authors.initials: F
authors.lastname: Otvos
authors.forename: E
authors.initials: E
authors.lastname: Malatynska
authors.forename: R J
authors.initials: RJ
authors.lastname: Knapp
authors.forename: F
authors.initials: F
authors.lastname: Porreca
authors.forename: V J
authors.initials: VJ
authors.lastname: Hruby
authors.forename: H I
authors.initials: HI
authors.lastname: Yamamura
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism*; D008297:Male; D008566:Membranes / Q000378:metabolism; D009019:Morphinans / Q000378:metabolism*; D009271:Naltrexone / Q000031:analogs & derivatives*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000378:metabolism*; D017465:Receptors, Opioid, delta
chemical_list: D007211:Indoles; D009019:Morphinans; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D009271:Naltrexone; C055382:naltrindole