Ethanol potentiates the function of the human dopamine transporter expressed in Xenopus oocytes.
Ethanol alters a variety of properties of brain dopaminergic neurons including firing rate, synthesis, release, and metabolism. Recent studies suggest that ethanol's action on central dopamine systems may also involve modulation of dopamine transporter (DAT) activity. The human DAT was expressed in Xenopus oocytes to examine directly the effects of ethanol on transporter function. [3H]Dopamine (100 nM) accumulation into DAT-expressing oocytes increased significantly in response to ethanol (10 min; 10-100 mM). In two-electrode voltage-clamp experiments, DAT-mediated currents were also enhanced significantly by ethanol (10-100 mM). The magnitude of the ethanol-induced potentiation of DAT function depended on ethanol exposure time and substrate concentration. Cell surface DAT binding ([3H]WIN 35,428; 4 nM) also increased as a function of ethanol exposure time. Thus, the increase in dopamine uptake was associated with a parallel increase in the number of DAT molecules expressed at the cell surface. These experiments demonstrate that DAT-mediated substrate translocation and substrate-associated ionic conductances are sensitive to intoxicating concentrations of ethanol and suggest that DAT may represent an important site of action for ethanol's effects on central dopaminergic transmission. A potential mechanism by which ethanol acts to enhance DAT function may involve regulation of DAT expression on the cell surface.
Mayfield
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RD
Waggoner Center for Alcohol and Addiction Research, University of Texas, Austin, Texas 78712, USA. dayne.mayfield@mail.utexas.edu
Maiya
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R
Keller
D
D
Zahniser
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NR
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D003042:Cocaine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors / Q000378:metabolism; D000431:Ethanol / Q000494:pharmacology*; D050485:GABA Plasma Membrane Transport Proteins; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism; D027361:Organic Anion Transporters; D018408:Patch-Clamp Techniques; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism; D014981:Xenopus; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D002352:Carrier Proteins; D002492:Central Nervous System Depressants; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D050485:GABA Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D027361:Organic Anion Transporters; D011956:Receptors, Cell Surface; C493214:SLC6A3 protein, human; C493216:Slc6a3 protein, rat; D000431:Ethanol; C021279:(1R-(exo,exo))-3-(4-fluorophenyl)-8-methyl-8- azabicyclo(3.2.1)octane-2-carboxylic acid, methyl ester; D005680:gamma-Aminobutyric Acid; D012313:RNA; D003042:Cocaine; D004298:Dopamine