title: Nicotine increases dopamine transporter function in rat striatum through a trafficking-independent mechanism.
abstract: In previous in vivo voltammetry studies, acute nicotine administration increased striatal dopamine clearance. The current study aimed to determine whether nicotine also increases [(3)H]dopamine uptake across the time course of the previous voltammetry studies and whether dopamine transporter trafficking to the cell surface mediates the nicotine-induced augmentation of dopamine clearance in striatum. Rats were administered nicotine (0.32 mg/kg, s.c.); striatal synaptosomes were obtained 5, 10, 40 or 60 min later. Nicotine increased (25%) the V(max) of [(3)H]dopamine uptake at 10 and 40 min. To determine whether the increase in V(max) was due to an increase in dopamine transporter density, [(3)H]GBR 12935 (1-(2-[bis(4-fluorophenyl)methoxy]ethyl)-4-(3-phenylpropyl)piperazine dihydrochloride) binding was performed using rat striatal membranes; no differences were found between nicotine and saline-control groups at 5, 10 or 40 min post-injection, indicating that nicotine did not increase striatal dopamine transporter density; however, [(3)H]GBR 12935 binding assays determine both cell surface and intracellular dopamine transporter. Changes in cellular dopamine transporter localization in striatum were determined using biotinylation and subfractionation approaches; no differences between nicotine and saline-control groups were observed at 10 and 40 min post-injection. These results suggest that the nicotine-induced increase in dopamine uptake and clearance in striatum may occur via a trafficking-independent mechanism.
authors.affiliation: University of Kentucky, Department of Pharmaceutical Sciences, College of Pharmacy, Lexington, Kentucky 40536-0082, USA.
authors.forename: Lisa S
authors.initials: LS
authors.lastname: Middleton
authors.forename: Subbu
authors.initials: S
authors.lastname: Apparsundaram
authors.forename: Kelley A
authors.initials: KA
authors.lastname: King-Pospisil
authors.forename: Linda P
authors.initials: LP
authors.lastname: Dwoskin
mesh_terms: D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D001692:Biological Transport / Q000502:physiology; D015153:Blotting, Western / Q000379:methods; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000493:pharmacokinetics; D050483:Dopamine Plasma Membrane Transport Proteins / Q000032:analysis / Q000502:physiology*; D005731:Ganglionic Stimulants / Q000008:administration & dosage / Q000494:pharmacology; D007279:Injections, Subcutaneous; D007700:Kinetics; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D005731:Ganglionic Stimulants; D010879:Piperazines; D014316:Tritium; D009538:Nicotine; C044630:1-(2 (diphenylmethoxy)ethyl)-4-(3-phenylpropyl)piperazine; D004298:Dopamine