Abstract
The 5-HT (5-hydroxytryptamine) system has been assigned a key role in the development of 3,4-dihydroxyphenyl-l-alanine (l-DOPA)-induced dyskinesia, mainly due to 5-HT neuronal ability to decarboxylate l-DOPA into dopamine. Nevertheless, knowledge of l-DOPA-induced events that could lead to development of dyskinesias are limited and therefore the present work has evaluated (i) the role of the 5-HT system in l-DOPA-derived dopamine synthesis when dopamine neurons are present, (ii) l-DOPA-induced effects on striatal dopamine release and clearance, and on 5-HT nerve fiber density, and (iii) the behavioral outcome of altered 5-HT transmission in dyskinetic rats. Chronoamperometric recordings demonstrated attenuated striatal l-DOPA-derived dopamine release (~30%) upon removal of 5-HT nerve fibers in intact animals. Interestingly, four weeks of daily l-DOPA treatment yielded similar-sized dopamine peak amplitudes in intact animals as found after a 5-HT-lesion. Moreover, chronic l-DOPA exposure attenuated striatal 5-HT nerve fiber density in the absence of dopamine nerve terminals. Furthermore, fluoxetine-induced altered 5-HT transmission blocked dyskinetic behavior via action on 5-HT1A receptors. Taken together, the results indicate a central role for the 5-HT system in l-DOPA-derived dopamine synthesis and in dyskinesia, and therefore potential l-DOPA-induced deterioration of 5-HT function might reduce l-DOPA efficacy as well as promote the upcoming of motor side effects.
Original language | English |
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Pages (from-to) | 73-86 |
Number of pages | 14 |
Journal | Neuroscience |
Volume | 260 |
DOIs | |
State | Published - Feb 28 2014 |
Bibliographical note
Funding Information:This study was funded by the Swedish Research Council Grant # 09917, The Umeå University Medical Faculty Funds, Konung Gustav V och drottning Victoria’s Fond, and Parkinsonfonden, Sweden. There are no conflicts of interest to be declared, neither financial nor personal.
Keywords
- 5-HT
- Dyskinesia
- Fluoxetine
- In vivo chronoamperometry
- L-DOPA
- WAY-100 635
ASJC Scopus subject areas
- General Neuroscience