title: Rats with persistently high exploratory activity have both higher extracellular dopamine levels and higher proportion of D(2) (High) receptors in the striatum.
abstract: Increases in both striatal dopamine release and the proportion of the D(2) receptors in the high affinity state (D(2) (High)) accompany the behavioral sensitization to psychostimulants, but it is not known whether the physiological substrate of the interindividual differences locomotor and exploratory behavior is similar. Thus, we examined whether persistently high spontaneous exploratory activity is associated with extracellular dopamine as well as the proportion of D(2) (High) in the striatum. Extracellular dopamine levels were found to be significantly higher in rats with high exploratory activity (high explorers, HE) as compared with low explorers (LE) in baseline conditions as well as after administration of amphetamine (0.5 mg/kg, i.p.). Also, the HE animals had significantly higher proportion of striatal D(2) (High) receptors than the LE-rats (43.8 +/- 4.4% and 22.5 +/- 1.5%, respectively). Thus, the present findings support the notion that concomitant higher extracellular dopamine levels and the proportion of D(2) (High) receptors in the striatum, whether naturally occurring and persistent or pharmacologically induced, are causally related to high behavioral activity.
authors.affiliation: Department of Psychology, Centre of Behavioral and Health Sciences, University of Tartu, 50410 Tartu, Estonia.
authors.forename: Aet
authors.initials: A
authors.lastname: Alttoa
authors.forename: Philip
authors.initials: P
authors.lastname: Seeman
authors.forename: Kadri
authors.initials: K
authors.lastname: Kõiv
authors.forename: Marika
authors.initials: M
authors.lastname: Eller
authors.forename: Jaanus
authors.initials: J
authors.lastname: Harro
mesh_terms: D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D003342:Corpus Striatum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism* / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology*; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D017551:Microdialysis / Q000379:methods; D011485:Protein Binding / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D014316:Tritium / Q000378:metabolism
chemical_list: D018492:Dopamine Antagonists; D018765:Dopamine Uptake Inhibitors; D017448:Receptors, Dopamine D2; D014316:Tritium; D004294:Domperidone; D000661:Amphetamine; D004298:Dopamine