title: Striatal inhibition of PKA prevents levodopa-induced behavioural and molecular changes in the hemiparkinsonian rat.
abstract: l-3,4-dihydroxyphenylalanine methyl ester hydrochloride (l-DOPA) is the gold standard for symptomatic treatment of Parkinson's disease (PD), but long-term therapy is associated with the emergence of abnormal involuntary movements (AIMS) known as l-DOPA-induced dyskinesias (LID). The molecular changes underlying LID are not completely understood. Using the 6-hydroxydopamine-lesioned rat model of PD, we showed that l-DOPA elicits profound alterations in the activity of three LID molecular markers, namely DeltaFosB, dopamine, cAMP-regulated phosphoprotein of 32 kDa (DARPP-32) and extracellular signal-regulated kinases 1 and 2 (ERK1/2), as well as in phosphorylation levels of the cytoskeletal-associated protein tau. These modifications are triggered by protein kinase A (PKA) activation and intermittent stimulation of dopamine receptors as they are totally prevented by intrastriatal injections of Rp-cAMPS, a PKA inhibitor, or by continuous administration of l-DOPA via subcutaneous mini-pump. Importantly, Rp-cAMPS does not modulate the positive effect of l-DOPA on locomotor deficits and significantly attenuates the emergence of AIMS in 6-hydroxydopamine hydrobromide-lesioned rats. Even if decreased PKA signalling in the striatum may represent a clinical challenge, these data provide novel evidence that PKA activation, through modification of striatal signalling and alterations of cytoskeletal constituents, plays a key role in the manifestation of LID.
authors.affiliation: Groupe de recherche en neurosciences, Département de chimie-biologie, Université du Québec à Trois-Rivières, 3351, boul. des Forges, C.P. 500, Trois-Rivières, QC, Canada G9A 5H7.
authors.forename: Manon
authors.initials: M
authors.lastname: Lebel
authors.forename: Laure
authors.initials: L
authors.lastname: Chagniel
authors.forename: Geneviève
authors.initials: G
authors.lastname: Bureau
authors.forename: Michel
authors.initials: M
authors.lastname: Cyr
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D015415:Biomarkers / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32 / Q000187:drug effects / Q000378:metabolism; D004409:Dyskinesia, Drug-Induced / Q000378:metabolism* / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects / Q000378:metabolism; D020233:Gait Disorders, Neurologic / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology; D015918:Infusion Pumps, Implantable; D007980:Levodopa / Q000009:adverse effects / Q000037:antagonists & inhibitors*; D008124:Locomotion / Q000187:drug effects / Q000502:physiology; D008297:Male; D020734:Parkinsonian Disorders / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004791:Enzyme Inhibitors; C483820:Fosb protein, rat; C497930:Ppp1r1b protein, rat; D016760:Proto-Oncogene Proteins c-fos; D013873:Thionucleotides; C016957:adenosine-3',5'-cyclic phosphorothioate; D007980:Levodopa; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D004298:Dopamine