PT  - JOURNAL ARTICLE
AU  - Dorota Zolkowska
AU  - Raka Jain
AU  - Richard B. Rothman
AU  - John S. Partilla
AU  - Bryan L. Roth
AU  - Vincent Setola
AU  - Thomas E. Prisinzano
AU  - Michael H. Baumann
TI  - Evidence for the Involvement of Dopamine Transporters in Behavioral Stimulant Effects of Modafinil
AID  - 10.1124/jpet.108.146142
DP  - 2009 May 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 738--746
VI  - 329
IP  - 2
4099  - http://jpet.aspetjournals.org/content/329/2/738.short
4100  - http://jpet.aspetjournals.org/content/329/2/738.full
SO  - J Pharmacol Exp Ther2009 May 01; 329
AB  - Modafinil is prescribed for numerous medical conditions, but the drug's mechanism of action is unclear. Here, we examined the interaction of modafinil with receptors and transporters in vitro and compared pharmacological effects of the drug with those produced by indirect dopamine (DA) agonists 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR12909) and (+)-methamphetamine (METH). Modafinil was screened at various receptors and transporters using binding assays. Transporter-mediated uptake and release were examined in rat brain synaptosomes. Effects of modafinil on motor activity and neurochemistry were determined in rats undergoing in vivo microdialysis in nucleus accumbens. Of the receptors and transporters assayed, modafinil displayed measurable potency only at DA transporters (DAT), inhibiting [3H]DA uptake, with an IC50 value of 4.0 μM. Accordingly, modafinil pretreatment (10 μM) antagonized METH-induced release of the DAT substrate [3H]1-methyl-4-phenylpyridinium. Intravenous modafinil (20 and 60 mg/kg) produced dose-dependent increases in motor activity and extracellular DA, without affecting serotonin (5-HT). Analogous results were observed for GBR12909 (1 and 3 mg/kg), whereas METH (0.3 and 1 mg/kg) increased DA and 5-HT. Locomotor effects of all drugs were positively correlated with dialysate DA (P < 0.001). Interestingly, modafinil pretreatment reduced METH-induced ambulation and DA release. Our data show that modafinil interacts with DAT sites in rat brain, a property shared with agonist medications under investigation for treating cocaine dependence. Nondopaminergic mechanisms may also contribute to the pharmacology of modafinil. Finally, the results suggest that modafinil should be tested as an adjunct for treating METH addiction. U.S. Government work not protected by U.S. copyright