[3H]GBR-12935 binding to human cerebral cortex is not to dopamine uptake sites.
The binding of the dopamine uptake inhibitor [3H]GBR-12935 to 16 regions of the human brain was investigated in competition experiments with increasing concentrations of GBR-12909, mazindol, and dopamine. The methodology used included a relatively high tissue concentration (8 mg/ml) and addition of 5 mM KCl in the assay buffer. GBR-12909 inhibited 80-90% of the binding in most regions, whereas dopamine only inhibited the binding in the striatum. Mazindol inhibited only part of the cortical binding at concentrations of > 1 microM, whereas the inhibition in the caudate and the putamen also contained a high-affinity component representing the dopamine uptake site. It is concluded that the [3H]GBR-12935 binding sensitive to GBR-12909 cannot be regarded as specific binding to the dopamine uptake site because the displaceable binding most likely is not related to the dopamine uptake site.
Allard
P
P
Department of Psychiatry, University of Umeå, Sweden.
Danielsson
M
M
Papworth
K
K
Marcusson
J O
JO
D000368:Aged; D001665:Binding Sites; D001692:Biological Transport; D002421:Caudate Nucleus / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D005625:Frontal Lobe / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D008297:Male; D008454:Mazindol / Q000378:metabolism / Q000494:pharmacology; D008875:Middle Aged; D009928:Organ Specificity; D010879:Piperazines / Q000378:metabolism*; D011699:Putamen / Q000378:metabolism; D014316:Tritium
D008024:Ligands; D010879:Piperazines; D014316:Tritium; C044630:1-(2 (diphenylmethoxy)ethyl)-4-(3-phenylpropyl)piperazine; D008454:Mazindol; D004298:Dopamine