ININFA   02677
INSTITUTO DE INVESTIGACIONES FARMACOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Analysis of structural plastic changes underlying L-DOPA induced dyskinesias in an animal model of Parkinson's disease
Autor/es:
TARAVINI I; SUÁREZ LM; GÓMEZ G; LARRAMENDY C; SABORIDO MD; ESCANDE M; BELFORTE J; RELA L; MORATALLA R; MURER GM; GERSHANIK O
Lugar:
Buenos Aires
Reunión:
Conferencia; 5th Special Conference of the International Society for Neurochemistry. ?Synapses and dendritic spines in health and disease?; 2012
Institución organizadora:
The International Society for Neurochemistry
Resumen:
Parkinson´s disease is a neurodegenerative disorder characterized by a gradual loss of dopaminergic neurons in the substantia nigra pars compacta, leading to a progressive reduction of dopamine levels in the striatum. L-DOPA remains the most efficacious treatment despite inducing severe motor complications (dyskinesia). L-DOPA-induced dyskinesias (LID) correlate with post-synaptic plastic changes in striatal neurons deprived of dopaminergic innervations. Once LID have been established they are rarely reversible. Our current hypothesis is that striatal structural changes involve an increase in synaptic connectivity of the D1 pathway. We have the following aims: (I) To develop an animal model of LID in transgenic mice expressing fluorescent proteins under control of the D1 (striatonigral neurons) or D2 (striatopalidal neurons) receptor promoter. (II) To analyze the structural modifications after L-DOPA treatment in each neuronal type by means of morphological analysis of their dendritic trees. Transgenic mice expressing red or green fluorescent markers in striatal neurons containing either the D1 or D2 receptor promoter were injected with 6-hydroxydopamine in the medial forebrain bundle and treated with increasing doses of L-DOPA (6, 12, 18 mg/kg). Fixed tissue sections from the striatum were obtained and striatal neurons were iontophoretically injected with Lucifer yellow. These cells were revealed immunohistochemically using DAB as a chromogen. To analyze the dendritic tree structure and the density of dendritic spines we used the NIH software ImageJ to perform the Sholl Analysis and Mercator Pro software to quantify the spines. We induced a unilateral severe injury of the nigrostriatal system in mice by injection of 6-hydroxydopamine and designed a protocol of L-DOPA administration that successfully induced a dyskinetic phenomenon. As expected we found a dose-dependent development of LID. Additionally, we have performed the first experiments of Lucifer yellow iontophoretic injections of striatal neurons. At present, we are analyzing if dyskinetogenic doses of L-DOPA can modify the synaptic connectivity of each neuronal type. Evaluation of dendritic tree morphology and dendritic spine number and shape is in progress.