Differential effect of MK 801 and scopolamine on c-fos expression induced by L-dopa in the striatum of 6-hydroxydopamine lesioned rats.
In rats with a unilateral 6-hydroxydopamine lesion of the dopaminergic nigro-striatal pathway, striatal D1-receptor-stimulated c-fos expression and turning behavior are positively modulated by D2 receptor stimulation and by blockade of N-methyl-D-aspartate (NMDA) or muscarinic receptors. Combined D1/D2 receptor stimulation by L-dopa activates c-fos in a manner not additive with muscarinic receptor blockade by scopolamine. On the other hand, blockade of NMDA receptors by MK 801 reduced c-fos expression induced by L-dopa while, depending on the dose of L-dopa, differentially affecting contralateral turning behavior. The results are interpreted to suggest that D2 receptor stimulation amplifies D1-receptor-mediated c-fos expression by two mechanisms differentially related to muscarinic and NMDA receptors.
Morelli
M
M
Department of Toxicology, University of Cagliari, Italy.
Pinna
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Fenu
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Carta
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Cozzolino
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Di Chiara
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D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects*; D016762:Genes, fos; D007150:Immunohistochemistry; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism*; D016627:Oxidopamine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000819:agonists; D017448:Receptors, Dopamine D2 / Q000819:agonists; D012601:Scopolamine / Q000494:pharmacology*; D013239:Stereotyped Behavior / Q000187:drug effects
D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D007980:Levodopa; D016291:Dizocilpine Maleate; D016627:Oxidopamine; D012601:Scopolamine