title: Effects of the adenosine A 2A antagonist KW 6002 (istradefylline) on pimozide-induced oral tremor and striatal c-Fos expression: comparisons with the muscarinic antagonist tropicamide.
abstract: Typical antipsychotic drugs, including haloperidol and pimozide, have been shown to produce parkinsonian motor effects such as akinesia and tremor. Furthermore, there is an antagonistic interaction between adenosine A(2A) and dopamine D(2) receptors in the basal ganglia, which is important for motor functions related to the production of parkinsonian symptoms. Several experiments were conducted to assess the effects of the selective adenosine A(2A) antagonist KW 6002 on both the motor and cellular effects of subchronic administration of pimozide. The motor test employed was tremulous jaw movements, which is used as a model of parkinsonian tremor. In addition, c-Fos expression in the ventrolateral neostriatum, which is the striatal area most associated with tremulous jaw movements, was used as a marker of striatal cell activity in animals that were tested in the behavioral experiments. Repeated administration of 1.0 mg/kg pimozide induced tremulous jaw movements and increased ventrolateral striatal c-Fos expression, while administration of 20.0 mg/kg of the atypical antipsychotic quetiapine did not. The tremulous jaw movements induced by pimozide were significantly reduced by co-administration of either the adenosine A(2A) antagonist KW 6002 or the muscarinic antagonist tropicamide. Pimozide-induced increases in ventrolateral striatal c-Fos expression were reduced by a behaviorally effective dose of KW 6002, but c-Fos expression in pimozide-treated rats was actually increased by tropicamide. These results indicate that two different drug manipulations that act to reduce tremulous jaw movements can have different effects on DA antagonist-induced c-Fos expression, suggesting that adenosine A(2A) antagonism and muscarinic receptor antagonism exert their motor effects by acting on different striatal circuits.
authors.affiliation: Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Betz
authors.forename: R
authors.initials: R
authors.lastname: Vontell
authors.forename: J
authors.initials: J
authors.lastname: Valenta
authors.forename: L
authors.initials: L
authors.lastname: Worden
authors.forename: K S
authors.initials: KS
authors.lastname: Sink
authors.forename: L
authors.initials: L
authors.lastname: Font
authors.forename: M
authors.initials: M
authors.lastname: Correa
authors.forename: T N
authors.initials: TN
authors.lastname: Sager
authors.forename: J D
authors.initials: JD
authors.lastname: Salamone
mesh_terms: D058917:Adenosine A2 Receptor Antagonists; D000818:Animals; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000037:antagonists & inhibitors; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D065127:Dopamine D2 Receptor Antagonists; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008297:Male; D008410:Masticatory Muscles / Q000294:innervation / Q000503:physiopathology; D018727:Muscarinic Antagonists / Q000494:pharmacology; D010868:Pimozide / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism; D011687:Purines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043705:Receptor, Adenosine A2A / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D014202:Tremor / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D014331:Tropicamide / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D058917:Adenosine A2 Receptor Antagonists; D014150:Antipsychotic Agents; D015415:Biomarkers; D065127:Dopamine D2 Receptor Antagonists; D018727:Muscarinic Antagonists; D016760:Proto-Oncogene Proteins c-fos; D011687:Purines; D043705:Receptor, Adenosine A2A; D017448:Receptors, Dopamine D2; D010868:Pimozide; C111599:istradefylline; D014331:Tropicamide