title: Dexmedetomidine decreases extracellular dopamine concentrations in the rat nucleus accumbens.
abstract: The effects of dexmedetomidine, a highly selective alpha(2)-adrenoceptor agonist, on extracellular dopamine (DA) concentrations in the nucleus accumbens of awake rats were collected via in vivo cerebral microdialysis and measured using HPLC with electrochemical detection. The administration of dexmedetomidine (DEX) at a low dose (2 microg/kg bolus i.v. over 2 min followed by a continuous infusion of 0.1 microg/kg per min) and a high dose (20 microg/kg bolus i.v. over 2 min followed by a continuous infusion of 1 microg/kg per min), significantly decreased extracellular dopamine concentrations in the nucleus accumbens. The observed decrease was dose-dependent, occurring sooner and to a greater magnitude in the rats receiving a high dose of DEX. This inhibitory modulation of accumbal dopamine was receptor-specific, as the decrease in extracellular DA produced by DEX was no longer evident following pre-treatment and co-infusion with the highly selective alpha(2)-adrenoceptor antagonist, atipamezole (ATZ). Thus, these data suggest that adrenoceptor agonists and antagonists may modulate dopaminergic neurotransmission via mechanisms that are specific to the alpha(2)-adrenoceptor.
authors.affiliation: Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, 622 West 168th Street PH 5, New York, NY 10032, USA. raw9@columbia.edu
authors.forename: R A
authors.initials: RA
authors.lastname: Whittington
authors.forename: L
authors.initials: L
authors.lastname: Virag
authors.forename: H O
authors.initials: HO
authors.lastname: Morishima
authors.forename: Y
authors.initials: Y
authors.lastname: Vulliemoz
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D020927:Dexmedetomidine / Q000008:administration & dosage / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects* / Q000378:metabolism*; D007275:Injections, Intravenous; D008297:Male; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000316:Adrenergic alpha-Agonists; D020927:Dexmedetomidine; D004298:Dopamine