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Nicotine- and methamphetamine-induced dopamine release evaluated with in-vivo binding of radiolabelled raclopride to dopamine D2 receptors: comparison with in-vivo microdialysis data

Cited 6 time in Web of Science Cited 8 time in Scopus
Authors
Kim, Sang Eun; Han, Seung-Moo
Issue Date
2009-01-22
Publisher
Cambridge University Press
Citation
International Journal of Neuropsychopharmacology 12, 833-841
Keywords
Analysis of VarianceAnimalsBrain/*drug effects/metabolism/radionuclide imagingDopamine/*metabolismDopamine Agents/*pharmacologyDose-Response Relationship, DrugDrug InteractionsMaleMethamphetamine/*pharmacologyMicrodialysis/methodsNicotine/*pharmacologyNicotinic Agonists/*pharmacologyProtein Binding/drug effectsRaclopride/metabolismRatsRats, Sprague-DawleyReceptors, Dopamine D2/*metabolismTritium/metabolism
Abstract
The effect of substances which alter extracellular dopamine (DA) concentration has been studied by measuring changes in the binding of radiolabelled raclopride, a DA D2 receptor ligand that is sensitive to endogenous DA. To better characterize the relationship between extracellular DA concentration and DA D2 receptor binding of raclopride, we compared the changes of extracellular DA concentration (measured using in-vivo microdialysis) and in-vivo [3H]raclopride binding induced by different doses of methamphetamine (Meth) and nicotine, drugs that enhance DA release with and without blocking DA transporters (DATs), respectively, in rat striatum. Nicotine elicited a modest increase of striatal extrasynaptic extracellular DA, while Meth produced a marked increase of striatal extrasynaptic DA in a dose-dependent manner. There was a close correlation between the decrease in [3H]raclopride in-vivo binding and the increase in extrasynaptic DA concentration induced by both nicotine (r2=0.95, p<0.001) and Meth (r2=0.98, p=0.001), supporting the usefulness of the radiolabelled raclopride-binding measurement for the non-invasive assessment of DA release following interventions in the living brain. However, the linear regression analysis revealed that the ratio of percent DA increase to percent [3H]raclopride binding reduction was 25-fold higher for Meth (34.8:1) than for nicotine (1.4:1). The apparent discrepancy in the extrasynaptic DA-[3H]raclopride binding relationship between the DA-enhancing drugs with and without DAT-blocking property indicates that the competition between endogenous DA and radiolabelled raclopride takes place at the intrasynaptic rather than extrasynaptic DA D2 receptors and reflects synaptic concentration of DA.
ISSN
1469-5111 (Electronic)
Language
English
URI
http://hdl.handle.net/10371/62539
DOI
https://doi.org/10.1017/S1461145708009826
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College of Medicine/School of Medicine (의과대학/대학원)Nuclear Medicine (핵의학전공)Journal Papers (저널논문_핵의학전공)
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