[(3)H]4-(Dimethylamino)-N-[4-(4-(2-methoxyphenyl)piperazin- 1-yl)butyl]benzamide, a selective radioligand for dopamine D(3) receptors. I. In vitro characterization.
4-(Dimethylamino)-N-(4-(4-(2-methoxyphenyl)piperazin-1-yl)butyl)benzamide (WC-10), a N-phenyl piperazine analog, has been shown to have high affinity and selectivity for dopamine D(3) receptors versus dopamine D(2) receptors (Chu et al. [2005] Bioorg Med Chem 13:77-87). In this study, WC-10 was radiolabeled with tritium (specific activity = 80 Ci/mmol) and [(3)H]WC-10 binding to genetically cloned dopamine D(2L) and D(3) receptors was evaluated in vitro. [(3)H]WC-10 binds with a 66-fold higher affinity to human HEK D(3) than HEK D(2L) receptors, with a dissociation constant (K(d)) of 1.2 nM at HEK D(3) receptors. However, [(3)H]WC-10 binds to rat Sf9 rD(3) receptors with a K(d) of 3.9 nM, a value that is 3-fold lower than binding to human HEK D(3) receptors and 40-fold value higher than binding to rat Sf9 rD(2L) receptors. The K(d) values obtained from saturation binding experiments were consistent with the results determined from kinetic (k(on) and k(off)) studies. The pharmacologic profiles of a series of dopaminergic drugs for inhibiting the binding of [(3)H]WC-10 to D(3) receptors was in agreement with previously reported data. In vitro autoradiography studies of rat and monkey brains show that [(3)H]WC-10 labeled D(3) sites in the striatal region.
Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Jinbin
J
Xu
Wenhua
W
Chu
Zhude
Z
Tu
Lynne A
LA
Jones
Robert R
RR
Luedtke
Joel S
JS
Perlmutter
Mark A
MA
Mintun
Robert H
RH
Mach
D000818:Animals; D001667:Binding, Competitive; D001923:Brain Chemistry / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000378:metabolism; D004347:Drug Interactions / Q000502:physiology; D006801:Humans; D015394:Molecular Structure; D010599:Pharmacokinetics; D010879:Piperazines / Q000737:chemistry / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D050637:Receptors, Dopamine D3 / Q000187:drug effects / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014316:Tritium / Q000378:metabolism
D015259:Dopamine Agents; D010879:Piperazines; D050637:Receptors, Dopamine D3; C543148:WC10 compound; D014316:Tritium; D004298:Dopamine