In vivo occupancy of the striatal dopamine uptake complex by various inhibitors does not predict their effects on locomotion.
We compared the ability of various dopamine (DA) uptake inhibitors to displace the in vivo striatal [3H]GBR 12783 (1-[2(diphenylmethoxy) ethyl)-4-(3-phenyl-1[3H]-2-propenyl)-piperazine) binding with their stimulant effect on locomotor activity on mice. GBR 12783 (8 mg/kg), GBR 13069 (10 mg/kg), cocaine (20 mg/kg), mazindol (3 mg/kg) or pyrovalerone (2 mg/kg) stimulated locomotion as long as they occupied the DA uptake complex. In contrast, nomifensine (3 mg/kg) did not stimulate locomotion although it competed with [3H]GBR 12783 for the occupancy of the DA uptake complex at a significant level (> 50%). Administered at their ED50 doses, GBR 12783, BTCP (N-[1-(2-benzo(b)thiophenyl)cyclohexyl]piperidine, GBR 13069, amineptine and dexamphetamine significantly increased locomotor activity whereas the other inhibitors tested did not. The locomotor response elicited by GBR 12783 (10 mg/kg) was not decreased by desipramine (20 mg/kg) nor by oxaprotiline (10 mg/kg). The increase in locomotion elicited by GBR 12783 was positively correlated with the basal locomotor activity of the mice. The stimulant effect of GBR 12783 was potentiated by SKF 525A and by budipine. Additional pharmacological properties might conceal the relationship between the effects of some DA uptake inhibitors on locomotion, and on in vivo occupancy of DA uptake sites.
Vaugeois
J M
JM
Unité de Neuropsychopharmacologie Expérimentale, URA 1170 CNRS, Faculté de Médicine and Pharmacie de Rouen, Saint-Etienne du Rouvray, France.
Bonnet
J J
JJ
Duterte-Boucher
D
D
Costentin
J
J
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists; D050483:Dopamine Plasma Membrane Transport Proteins; D004347:Drug Interactions; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010879:Piperazines / Q000378:metabolism / Q000494:pharmacology*
D018492:Dopamine Antagonists; D050483:Dopamine Plasma Membrane Transport Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010879:Piperazines; C039737:1-(2-(diphenylmethoxy)ethyl)-4-(3-phenyl-2-propenyl)piperazine; D003577:Cytochrome P-450 Enzyme System; D004298:Dopamine