Fluctuation of the dopamine uptake inhibition potency of cocaine, but not amphetamine, at mammalian cells expressing the dopamine transporter

DOI

10.1016/j.brainres.2006.11.018

Document Type

Journal Article

Publication Date

2-2-2007

Publication Title

Brain Research

Volume

1131

Issue

1

First Page

68

Last Page

76

ISSN

68993

Keywords

Addiction, Amphetamine, Cocaine, Dopamine, Drug abuse, Transporter

Abstract

Cocaine, amphetamines and other psychostimulants inhibit synaptic dopamine uptake by interfering with dopamine transporter (DAT) function. The resultant potentiation of dopaminergic neurotransmission is associated with psychostimulant addiction. Fluctuations in dopamine uptake inhibition potency (DUIP) were observed for classical DAT blockers including cocaine, mazindol, methylphenidate (Ritalin™) and benztropine in CHO cells expressing wild type DAT; cocaine potency also decreased in DAT-expressing non-neuronal COS-7 cells and neuronal N2A neuroblastoma cells. In contrast, the DAT substrate (+)-amphetamine did not display this DUIP fluctuation. In parallel experiments, no fluctuation was observed for the apparent binding affinities of these 5 drugs. The DUIP decrease appeared to correlate with an increase in cell surface DAT expression level, as measured by Bmax values and confocal microscopy. The fact that the DUIP profile of amphetamine diverged from that of the classical DAT blockers is consistent with the idea of fundamental differences between the mechanisms of abused psychostimulant DAT substrates and inhibitors. Identification of the cellular factors that underlie the DAT inhibitor DUIP fluctuation phenomenon may be relevant to anti-psychostimulant drug discovery efforts. © 2006 Elsevier B.V. All rights reserved.

Open Access

Green Accepted

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