Characterization of [3H]naltrindole binding to delta opioid receptors in rat brain.
[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.
Yamamura
M S
MS
Department of Pharmacology, University of Arizona, College of Medicine, Tucson 85724.
Horvath
R
R
Toth
G
G
Otvos
F
F
Malatynska
E
E
Knapp
R J
RJ
Porreca
F
F
Hruby
V J
VJ
Yamamura
H I
HI
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
D007211:Indoles; D009019:Morphinans; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D009271:Naltrexone; C055382:naltrindole