title: The unique psychostimulant profile of (±)-modafinil: investigation of behavioral and neurochemical effects in mice.
abstract: Blockade of dopamine (DA) reuptake via the dopamine transporter (DAT) is a primary mechanism identified as underlying the therapeutic actions of (±)-modafinil (modafinil) and its R-enantiomer, armodafinil. Herein, we explored the neurochemical and behavioral actions of modafinil to better characterize its psychostimulant profile. Swiss-Webster mice were implanted with microdialysis probes in the nucleus accumbens shell (NAS) or core (NAC) to evaluate changes in DA levels related to acute reinforcing actions of drugs of abuse. Additionally, subjective effects were studied in mice trained to discriminate 10 mg/kg cocaine (i.p.) from saline. Modafinil (17-300 mg/kg, i.p.) significantly increased NAS and NAC DA levels that at the highest doses reached ~300% at 1 h, and lasted > 6 h in duration. These elevated DA levels did not show statistically significant regional differences between the NAS and NAC. Modafinil produced cocaine-like subjective effects at 56-100 mg/kg when administered at 5 and 60 min before the start of the session, and enhanced cocaine effects when the two were administered in combination. Despite sharing subjective effects with cocaine, modafinil's psychostimulant profile was unique compared to that of cocaine and like compounds. Modafinil had lower potency and efficacy than cocaine in stimulating NAS DA. In addition, the cocaine-like subjective effects of modafinil were obtained at lower doses and earlier onset times than expected based on its dopaminergic effects. These studies suggest that although inhibition of DA reuptake may be a primary mechanism underlying modafinil's therapeutic actions, non DA-dependent actions may be playing a role in its psychostimulant profile.
authors.affiliation: Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA.
authors.forename: Maddalena
authors.initials: M
authors.lastname: Mereu
authors.affiliation: Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Chun
authors.affiliation: Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Prisinzano
authors.affiliation: Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA.|Medicinal Chemistry Section, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA.
authors.forename: Amy H
authors.initials: AH
authors.lastname: Newman
authors.affiliation: Psychobiology Section, Molecular Neuropsychiatry Research Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD, USA.
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Katz
authors.affiliation: Medication Development Program, Molecular Targets and Medications Discovery Branch, Department of Health and Human Services, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, 333 Cassell Drive, Baltimore, MD, 21224, USA.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Tanda
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001559:Benzhydryl Compounds / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology; D050483:Dopamine Plasma Membrane Transport Proteins / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D017551:Microdialysis / Q000379:methods; D000077408:Modafinil
chemical_list: D001559:Benzhydryl Compounds; D000697:Central Nervous System Stimulants; D050483:Dopamine Plasma Membrane Transport Proteins; D003042:Cocaine; D000077408:Modafinil
keywords: 
  ADHD
  ; cocaine abuse and addiction; dopamine microdialysis; methylphenidate; modafinil; nucleus accumbens shell