Divergent effect of the selective D3 receptor agonist pd-128,907 on locomotor activity in Roman high- and low-avoidance rats: relationship to NGFI-A gene expression in the Calleja islands.
BACKGROUND
The inbred Roman high- (RHA-I) and low-avoidance (RLA-I) rats, differing in dopaminergic activity and novelty/substance-seeking profiles, may be a suitable model to study the implication of the dopaminergic system in vulnerability to drug abuse. Differences in D3 receptor binding recently described between the two strains (Guitart-Masip M, Johansson B, Fernández-Teruel A, Cañete T, Tobeña A, Terenius L, Giménez-Llort L, Neuroscience 142:1231-1243, 2006b) may be important in shaping the aforementioned differences in novelty seeking.


OBJECTIVE
The aim of the present work was to study the effect of D3 receptor activation on novelty-induced locomotor activity in these two strains of rats.


METHODS
We administered saline and PD-128,907 (0.01 and 0.1 mg/kg), a putative D3 receptor agonist, to the Roman rats and studied the locomotor activity when animals were placed in a novel environment. Thereafter, by means of in situ hybridization, nerve growth factor inducible clone A (NGFI-A) mRNA was measured in the striatum and the Calleja islands of these animals.


RESULTS
We found that RLA-I rats showed stronger locomotor inhibition than RHA-I rats after PD-128,907 administration. Moreover, RLA-I rats showed stronger reduction of NGFI-A mRNA in the Calleja islands than RHA-I rats.


CONCLUSIONS
These results, together with previous findings, suggest that differences in D3 receptor expression in the Calleja islands may contribute to the divergent behavioral effect of PD-128,907 administration in the two strains of Roman rats.
Guitart-Masip
Marc
M
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neuroscience, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain.
Johansson
Björn
B
Fernández-Teruel
Albert
A
Tobeña
Adolf
A
Giménez-Llort
Lydia
L
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001578:Benzopyrans / Q000494:pharmacology*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D051766:Early Growth Response Protein 1 / Q000235:genetics*; D005106:Exploratory Behavior / Q000187:drug effects*; D015870:Gene Expression / Q000187:drug effects; D017403:In Situ Hybridization; D007266:Inhibition, Psychological; D020670:Islands of Calleja / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D010078:Oxazines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D011919:Rats, Inbred Strains; D050637:Receptors, Dopamine D3 / Q000819:agonists* / Q000235:genetics; D012931:Social Environment
D001578:Benzopyrans; D018491:Dopamine Agonists; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D010078:Oxazines; D012333:RNA, Messenger; D050637:Receptors, Dopamine D3; C062458:3,4,4a,10b-tetrahydro-4-propyl-2H,5H-(1)benzopyrano(4,3-b)-1,4-oxazin-9-ol