QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: jpet.104.067314v1 310/3/1142    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Wilhelm, C. J. Articles by Janowsky, A. Search for Related Content PubMed PubMed Citation Articles by Wilhelm, C. J. Articles by Janowsky, A.

NEUROPHARMACOLOGY

Effects of Methamphetamine and Lobeline on Vesicular Monoamine and Dopamine Transporter-Mediated Dopamine Release in a Cotransfected Model System

Research Service, Veterans Affairs Medical Center, and Departments of Physiology and Pharmacology (C.J.W., A.J.E., A.J.), Psychiatry (A.J.), and Behavioral Neuroscience (A.J.), Oregon Health and Science University, Portland, Oregon; and GlaxoSmithKline (P.G.L.), King of Prussia, Pennsylvania

Dopamine (DA) retention and drug-induced release kinetics were characterized in human embryonic kidney (HEK)-293 cells stably coexpressing the human DA transporter (hDAT) and human vesicular monoamine transporter (hVMAT2). Cofunction of hDAT and hVMAT2 caused greater retention of [³H]DA at 20 min (37°C), or 45 min (22°C) compared with cells that were treated with dihydrotetrabenazene (DHTB) to block the hVMAT2. In hDAT- and hVMAT2-coexpressing cells treated with DHTB during [³H]DA loading, methamphetamine (METH)-induced efflux was only 20% of preloaded [³H]DA, compared with 50 to 60% efflux in the absence of DHTB. Interestingly, the presence of DHTB (during release only) increased the potency and efficacy of METH at inducing [³H]DA release (without DHTB: EC₅₀ = 33.8 µM, maximal release 51%; release with DHTB: EC₅₀ = 3.2 µM, maximal release 61%), suggesting that the effects of METH and DHTB on vesicular storage are additive. High concentrations of lobeline induced a statistically significant release of [³H]DA from HEK-hDAT-hVMAT2 cells, but only in the absence of DHTB, suggesting an hVMAT2-mediated effect. Likewise, lobeline did not induce a significant release of [³H]DA from HEK-hDAT cells. The substrates DA and p-tyramine induced robust release of preloaded [³H]DA from cotransfected cells. Cocaine was somewhat effective at blocking substrate-induced [³H]DA efflux. These results suggest that coexpression of the hDAT and hVMAT2 can be used as a model system to distinguish functional pools of DA and to quantify differences in drug effects on DA disposition. In addition, cotransfected cells can be used to determine mechanisms of simultaneous drug interactions at multiple sites.

Address correspondence to: Dr. Aaron Janowsky, Research Service 22), Veterans Affairs Medical Center, 3710 S.W. U.S. Veterans Hospital Portland, OR 97239. E-mail: janowsky{at}ohsu.edu

This article has been cited by other articles:

				Z. Xie and G. M. Miller A Receptor Mechanism for Methamphetamine Action in Dopamine Transporter Regulation in Brain J. Pharmacol. Exp. Ther., July 1, 2009; 330(1): 316 - 325. [Abstract] [Full Text] [PDF]