Cocaine induction of dopamine transporter trafficking to the plasma membrane.
Several previous human postmortem experiments have detected an increase in striatal [(3)H]WIN 35428 binding to the dopamine transporter (DAT) in chronic cocaine users. However, animal experiments have found considerable variability in DAT radioligand binding levels in brain after cocaine administration, perhaps caused by length and dose of treatment and type of radioligand used. The present experiments tested the hypothesis that [(3)H]WIN 35428 binding and [(3)H]dopamine uptake would be increased by exposure to cocaine through alterations in DAT cellular trafficking, rather than increased protein synthesis. Experiments were conducted in stably hDAT-transfected N2A cells and assessed the dose response and time course of cocaine effects on [(3)H]WIN 35428 binding to the DAT, [(3)H]dopamine uptake, measures of DAT protein and mRNA, as well as DAT subcellular location. Cocaine doses of 10(-6) M caused statistically significant increases in [(3)H]WIN 35428 binding and [(3)H]dopamine uptake after 12 and 3 h, respectively. Despite these increases in DAT function, there was no change in DAT total protein or mRNA. Immunofluorescence and biotinylation experiments indicated that cocaine treatment induced increases in plasma membrane DAT immunoreactivity and intracellular decreases. The present model system may further our understanding of regulatory alterations in DAT radioligand binding and function caused by cocaine exposure.
Little
Karley Y
KY
Department of Psychiatry, University of Michigan, Ann Arbor, Michigan, USA. kylittle@umich.edu
Elmer
Lawrence W
LW
Zhong
Huailing
H
Scheys
Joshua O
JO
Zhang
Lian
L
D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D003042:Cocaine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D004347:Drug Interactions; D006801:Humans; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009419:Nerve Tissue Proteins; D010766:Phosphorylation; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D011869:Radioligand Assay; D015290:Second Messenger Systems / Q000502:physiology; D012701:Serotonin / Q000378:metabolism; D013347:Subcellular Fractions; D014162:Transfection; D014316:Tritium; D014407:Tumor Cells, Cultured
D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; C493214:SLC6A3 protein, human; C493215:Slc6a3 protein, mouse; D014316:Tritium; D012701:Serotonin; C021279:(1R-(exo,exo))-3-(4-fluorophenyl)-8-methyl-8- azabicyclo(3.2.1)octane-2-carboxylic acid, methyl ester; D003042:Cocaine; D004298:Dopamine