Relationship between conformational changes in the dopamine transporter and cocaine-like subjective effects of uptake inhibitors.

TY - JOUR

T1 - Relationship between conformational changes in the dopamine transporter and cocaine-like subjective effects of uptake inhibitors.

AU - Løland, Claus Juul

AU - Desai, Rajeev I

AU - Zou, Mu-Fa

AU - Cao, Jianjing

AU - Grundt, Peter

AU - Gerstbrein, Klaus

AU - Sitte, Harald H

AU - Newman, Amy Hauck

AU - Katz, Jonathan L

AU - Gether, Ulrik

N1 - Keywords: Alanine; Amino Acid Substitution; Animals; Biological Transport; COS Cells; Cercopithecus aethiops; Cocaine; Data Interpretation, Statistical; Discrimination Learning; Dopamine Plasma Membrane Transport Proteins; Dopamine Uptake Inhibitors; Dose-Response Relationship, Drug; Inhibitory Concentration 50; Male; Mesylates; Motor Activity; Protein Binding; Protein Conformation; Rats; Rats, Sprague-Dawley; Transfection

PY - 2007

Y1 - 2007

N2 - Cocaine exerts its stimulatory effect by inhibiting the dopamine transporter (DAT). However, novel benztropine- and rimcazole-based inhibitors show reduced stimulant effects compared with cocaine, despite higher affinity and selectivity for DAT. To investigate possible mechanisms, we compared the subjective effects of different inhibitors with their molecular mode of interaction at the DAT. We determined how different inhibitors affected accessibility of the sulfhydryl-reactive reagent [2-(trimethylammonium)ethyl]-methanethiosulfonate to an inserted cysteine (I159C), which is accessible when the extracellular transporter gate is open but inaccessible when it is closed. The data indicated that cocaine analogs bind an open conformation, whereas benztropine and rimcazole analogs bind a closed conformation. Next, we investigated the changes in inhibition potency of [(3)H]dopamine uptake of the compounds at a mutant DAT (Y335A) characterized by a global change in the conformational equilibrium. We observed a close relationship between the decrease in potencies of inhibitors at this mutant and cocaine-like responding in rats trained to discriminate cocaine from saline injections. Our data suggest that chemically different DAT inhibitors stabilize distinct transporter conformations and that this in turn affects the cocaine-like subjective effects of these compounds in vivo.

AB - Cocaine exerts its stimulatory effect by inhibiting the dopamine transporter (DAT). However, novel benztropine- and rimcazole-based inhibitors show reduced stimulant effects compared with cocaine, despite higher affinity and selectivity for DAT. To investigate possible mechanisms, we compared the subjective effects of different inhibitors with their molecular mode of interaction at the DAT. We determined how different inhibitors affected accessibility of the sulfhydryl-reactive reagent [2-(trimethylammonium)ethyl]-methanethiosulfonate to an inserted cysteine (I159C), which is accessible when the extracellular transporter gate is open but inaccessible when it is closed. The data indicated that cocaine analogs bind an open conformation, whereas benztropine and rimcazole analogs bind a closed conformation. Next, we investigated the changes in inhibition potency of [(3)H]dopamine uptake of the compounds at a mutant DAT (Y335A) characterized by a global change in the conformational equilibrium. We observed a close relationship between the decrease in potencies of inhibitors at this mutant and cocaine-like responding in rats trained to discriminate cocaine from saline injections. Our data suggest that chemically different DAT inhibitors stabilize distinct transporter conformations and that this in turn affects the cocaine-like subjective effects of these compounds in vivo.

U2 - 10.1124/mol.107.039800

DO - 10.1124/mol.107.039800

M3 - Journal article

C2 - 17978168

SN - 0026-895X

VL - 73

SP - 813

EP - 823

JO - Molecular Pharmacology

JF - Molecular Pharmacology

IS - 3

ER -