Preference for distinct functional conformations of the dopamine transporter alters the relationship between subjective effects of cocaine and stimulation of mesolimbic dopamine

Stephen J. Kohut, Takato Hiranita, Soo Kyung Hong, Aaron L. Ebbs, Valeria Tronci, Jennifer Green, Linda Garcés-Ramírez, Lauren E. Chun, Maddalena Mereu, Amy H. Newman, Jonathan L. Katz, Gianluigi Tanda

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

Background: Subjective effects of cocaine are mediated primarily by dopamine (DA) transporter (DAT) blockade. The present study assessed the hypothesis that different DAT conformational equilibria regulate differences in cocaine-like subjective effects and extracellular DA induced by diverse DA-uptake inhibitors (DUIs). Methods: The relationship between cocaine-like subjective effects and stimulation of mesolimbic DA levels by standard DUIs (cocaine, methylphenidate, WIN35,428) and atypical DUIs (benztropine analogs: AHN1-055, AHN2-005, JHW007) was investigated using cocaine discrimination and DA microdialysis procedures in rats. Results: All drugs stimulated DA levels with different maxima and time courses. Standard DUIs, which preferentially bind outward-facing DAT conformations, fully substituted for cocaine, consistently producing cocaine-like subjective effects at DA levels of 100-125% over basal values, regardless of dose or pretreatment time. The atypical DUIs, with DAT binding minimally affected by DAT conformation, produced inconsistent cocaine-like subjective effects. Full effects were obtained, if at all, only at a few doses and pretreatment times and at DA levels 600-700% greater than basal values. Importantly, the linear, time-independent, relationship between cocaine-like subjective effects and DA stimulation obtained with standard DUIs was not obtained with the atypical DUIs. Conclusions: These results suggest a time-related desensitization process underlying the reduced cocaine subjective effects of atypical DUIs that may be differentially induced by the binding modalities identified using molecular approaches. Since the DAT is the target of several drugs for treating neuropsychiatric disorders, such as attention-deficit/hyperactivity disorder, these results help to identify safe and effective medications with minimal cocaine-like subjective effects that contribute to abuse liability.

Original languageEnglish (US)
Pages (from-to)802-809
Number of pages8
JournalBiological Psychiatry
Volume76
Issue number10
DOIs
StatePublished - 2014
Externally publishedYes

Keywords

  • ADHD
  • Benztropine analogs
  • Cocaine discrimination
  • Dopamine microdialysis
  • Drug abuse and addiction
  • Nucleus accumbens shell

ASJC Scopus subject areas

  • Biological Psychiatry

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