Activation of N-methyl-D-aspartate receptors in the feline retrorubral nucleus elicits orofacial dyskinesia.
Stimulation of dopamine receptors within a circumscribed subregion of the feline caudate nucleus, that is the anterodorsal part of this nucleus, with dopamine or the dopamine receptor agonist (3,4-dihydroxyphenylimino)-2-imidazoline (DPI) elicits orofacial dyskinesia. Orofacial dyskinesia is a syndrome of tic-like contractions of the facial muscles which ends with a tongue protrusion. Afferent fibres of the anterodorsal part of the caudate nucleus are known to emanate from the retrorubral nucleus, including the dopaminergic A8 cell group. The present study was undertaken to investigate whether excitation of A8 cells can mediate and/or modulate orofacial dyskinesia. For this purpose, the activity of the retrorubral nucleus was manipulated with local injections of N-methyl-D-aspartate (NMDA). These local injections into the retrorubral nucleus were subsequently combined with manipulations of the dopamine transmission in the anterodorsal part of the caudate nucleus with local injections of DPI. The present study shows that injections of NMDA into the retrorubral nucleus elicits orofacial dyskinesia. This effect is dose-dependent, NMDA-specific, and inhibited by intra-caudate injections of DPI.
Department of Psychoneuropharmacology, University of Nijmegen, Netherlands.
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Bemelmans
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Cools
D000818:Animals; D002395:Catecholamines / Q000494:pharmacology; D002415:Cats; D002421:Caudate Nucleus / Q000187:drug effects / Q000502:physiology; D018491:Dopamine Agonists / Q000494:pharmacology; D004409:Dyskinesia, Drug-Induced / Q000503:physiopathology*; D004423:Ear / Q000503:physiopathology; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D048288:Imidazolines; D008297:Male; D016202:N-Methylaspartate / Q000633:toxicity; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000502:physiology*; D012012:Red Nucleus / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D014059:Tongue / Q000503:physiopathology
D002395:Catecholamines; D018491:Dopamine Agonists; D018690:Excitatory Amino Acid Agonists; D048288:Imidazolines; D016194:Receptors, N-Methyl-D-Aspartate; D016202:N-Methylaspartate; C011775:(3,4-dihydroxyphenylamino)-2-imidazoline