title: The role of the dorsal raphe nucleus in the development, expression, and treatment of L-dopa-induced dyskinesia in hemiparkinsonian rats.
abstract: Convergent evidence indicates that in later stages of Parkinson's disease raphestriatal serotonin neurons compensate for the loss of nigrostriatal dopamine neurons by converting and releasing dopamine derived from exogenous administration of the pharmacotherapeutic L-3,4-dihydroxyphenyl-L-alanine (L-dopa). Because the serotonin system is not equipped with dopamine autoregulatory mechanisms, it has been postulated that raphe-mediated striatal dopamine release may fluctuate dramatically. These fluctuations may portend the development of abnormal involuntary movements called L-dopa-induced dyskinesia (LID). As such, it has been hypothesized that reducing the activity of raphestriatal neurons could dampen supraphysiological stimulation of striatal dopamine receptors thereby alleviating LID. To directly address this, the current study employed the rodent model of LID to investigate the contribution of the rostral raphe nuclei (RRN) in the development, expression and treatment of LID. In the first study, dual serotonin/dopamine selective lesions of the RRN and medial forebrain bundle, respectively, verified that the RRN are essential for the development of LID. In a direct investigation into the neuroanatomical specificity of these effects, microinfusions of +/-8-OH-DPAT into the intact dorsal raphe nucleus dose-dependently attenuated the expression of LID without affecting the antiparkinsonian efficacy of L-dopa. These current findings reveal the integral contribution of the RRN in the development and expression of LID and implicate a prominent role for dorsal raphe 5-HT1AR in the efficacious properties of 5-HT1AR agonists.
authors.affiliation: Behavioral Neuroscience Program, Department of Psychology, State University of New York at Binghamton, Binghamton, New York 13902-6000, USA.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Eskow
authors.forename: Kristin B
authors.initials: KB
authors.lastname: Dupre
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Barnum
authors.forename: Sando O
authors.initials: SO
authors.lastname: Dickinson
authors.forename: John Y
authors.initials: JY
authors.lastname: Park
authors.forename: Christopher
authors.initials: C
authors.lastname: Bishop
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004409:Dyskinesia, Drug-Induced / Q000503:physiopathology*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007980:Levodopa; D008297:Male; D008474:Medial Forebrain Bundle / Q000187:drug effects / Q000503:physiopathology; D009043:Motor Activity / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D011903:Raphe Nuclei / Q000187:drug effects / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D018490:Serotonin Agents / Q000494:pharmacology
chemical_list: D018490:Serotonin Agents; D015102:3,4-Dihydroxyphenylacetic Acid; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D007980:Levodopa; D006897:Hydroxyindoleacetic Acid; D004298:Dopamine