Mechanisms underlying methamphetamine-induced dopamine transporter complex formation.
Repeated, high-dose methamphetamine (METH) administrations cause persistent dopaminergic deficits in rodents, nonhuman primates, and humans. In rats, this treatment also causes the formation of high-molecular mass (greater than approximately 120 kDa) dopamine transporter (DAT)-associated complexes, the loss of DAT monomer immunoreactivity, and a decrease in DAT function, as assessed in striatal synaptosomes prepared 24 h after METH treatment. The present study extends these findings by demonstrating the regional selectivity of DAT complex formation and monomer loss because these changes in DAT immunoreactivity were not observed in the nucleus accumbens. Furthermore, DAT complex formation was not a consequence limited to METH treatment because it was also caused by intrastriatal administration of 6-hydroxydopamine. Pretreatment with the D2 receptor antagonist, eticlopride [S-(-)-3-chloro-5-ethyl-N-[(1-ethyl-2-pyrrolidinyl)methyl]-6-hydroxy-2-methoxybenzamide hydrochloride], but not the D1 receptor antagonist, SCH23390 [R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride], attenuated METH-induced DAT complex formation. Eticlopride pretreatment also attenuated METH-induced DAT monomer loss and decreases in DAT function; however, the attenuation was much less pronounced than the effect on DAT complex formation. Finally, results also revealed a negative correlation between METH-induced DAT complex formation and DAT activity. Taken together, these data further elucidate the underlying mechanisms and the functional consequences of repeated administrations of METH on the DAT protein. Furthermore, these data suggest a multifaceted role for D2 receptors in mediating METH-induced alterations of the DAT and its function.
Hadlock
Gregory C
GC
Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, UT 84112, USA.
Baucum
Anthony J
AJ
King
Jill L
JL
Horner
Kristen A
KA
Cook
Glen A
GA
Gibb
James W
JW
Wilkins
Diana G
DG
Hanson
Glen R
GR
Fleckenstein
Annette E
AE
D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D015153:Blotting, Western; D003627:Data Interpretation, Statistical; D004298:Dopamine / Q000378:metabolism; D018492:Dopamine Antagonists / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D050483:Dopamine Plasma Membrane Transport Proteins / Q000096:biosynthesis*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology*; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D016627:Oxidopamine; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D012457:Salicylamides / Q000494:pharmacology; D013563:Sympathectomy, Chemical; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D050483:Dopamine Plasma Membrane Transport Proteins; D018765:Dopamine Uptake Inhibitors; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C534628:SCH 23390; D012457:Salicylamides; D008694:Methamphetamine; D016627:Oxidopamine; C045989:eticlopride; D004298:Dopamine