Neophobia and cortical and subcortical binding of the dopamine D2 receptor antagonist [3H]-raclopride.
The potential role of dopamine system in response to novelty was analysed using the selective dopamine D2 receptor antagonist, raclopride, in behavioral and biochemical assays, in rats (the open field test, and specific binding of [3H]-raclopride, within different brain structures measured with autoradiography). It was found that raclopride at a low dose (50 microg/kg, IP) caused anxiolytic-like effect (increased the anti-thigmotactic index), whereas at a higher dose (500 microg/kg, IP) produced general inhibitory influence, and decreased the anti-thigmotactic index. Analysis of the behavioral and biochemical results of the experiment revealed a significant negative correlation between the ligand binding in the substantia nigra pars reticulata (SNR), and the number of entries into the central sector of the open field (r=-0.48, p<0.05), as well as the positive correlation between time spent in the central sector of the open field and [3H]-raclopride binding within nucleus accumbens septi (r=0.57, p<0.05). Factor analysis revealed a Factor 1 (eigenvalue=3.361) grouping parameters of central entries into the open field and [3H]-raclopride binding in the SNR (factor loadings are 0.814 and 0.703 respectively), indicating that both phenomena are under control of a similar central process. The above data are discussed in relation to the structure dependent dopamine D2 receptor mechanisms in a rat response to novelty.
Siemiatkowski
Marek
M
Department of Pharmacology and Physiology of the Nervous System, Poland.
Maciejak
Piotr
P
Wisłowska
Aleksandra
A
Zienowicz
Małgorzata
M
Sienkiewicz-Jarosz
Helena
H
Szyndler
Janusz
J
Członkowska
Agnieszka I
AI
Bidziński
Andrzej
A
Gryczyńska
Alicja
A
Płaźnik
Adam
A
D000818:Animals; D001345:Autoradiography; D001522:Behavior, Animal / Q000187:drug effects*; D002540:Cerebral Cortex / Q000378:metabolism*; D018492:Dopamine Antagonists / Q000378:metabolism*; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D005106:Exploratory Behavior / Q000187:drug effects*; D005163:Factor Analysis, Statistical; D008297:Male; D020891:Raclopride / Q000378:metabolism* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D020891:Raclopride