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Riluzole administration to rats with levodopa-induced dyskinesia analyzed by RRBS

ABSTRACT: Dyskinesias are characterized by abnormal repetitive involuntary movements due to dysfunctional neuronal activity. Although levodopa-induced dyskinesia, characterized by tic-like abnormal involuntary movements, has no clinical treatment for Parkinson’s disease patients, animal studies indicate that Riluzole, which interferes with glutamatergic neurotransmission, can improve the phenotype. The rat model of levodopa-induced dyskinesia is a unilateral lesion with 6-hydroxydopamine in the medial forebrain bundle, followed by the repeated administration of levodopa. The molecular pathomechanism of levodopa-induced dyskinesia is still not deciphered, however implication of epigenetic mechanisms was suggested. In this study, we investigated the striatum for DNA methylation alterations under chronic levodopa treatment with or without co-treatment with Riluzole. Our data show that the lesioned and contralateral striata have nearly identical DNA methylation profiles. Chronic levodopa and levodopa+Riluzole treatments led to DNA methylation loss, particularly outside of promoters, in gene bodies and CpG poor regions. We observed that several genes involved in the levodopa-induced dyskinesia underwent methylation changes. Furthermore, the Riluzole co-treatment, which improved the phenotype, pinpointed specific methylation targets, with more than 20% methylation difference relative to levodopa treatment alone. These findings indicate potential new druggable targets for levodopa-induced dyskinesia.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE176004 | GEO | 2021/06/03

REPOSITORIES: GEO

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Project description:L-3,4-dihydroxyphenylalanine (levodopa) treatment is the major pharmacotherapy for Parkinson's disease. However, almost all patients receiving levodopa eventually develop debilitating involuntary movements (dyskinesia). While it is known that striatal spiny projection neurons (SPNs) are involved in the genesis of this movement disorder, the molecular basis of dyskinesia is not understood. In this study, we identify distinct cell-type-specific gene expression changes that occur in sub-classes of SPNs upon induction of a parkinsonian lesion followed by chronic levodopa treatment. We identify several hundred genes whose expression is correlated with levodopa dose, many of which are under the control of AP-1 and ERK signaling. In spite of homeostatic adaptations involving several signaling modulators, AP-1-dependent gene expression remains highly dysregulated in direct pathway SPNs (dSPNs) upon chronic levodopa treatment. We also discuss which molecular pathways are most likely to dampen abnormal dopaminoceptive signaling in spiny projection neurons, hence providing potential targets for antidyskinetic treatments in Parkinson's disease. To profile the cell-type-specific responses of striatal spiny projection neurons (SPNs) to striatal dopamine depletion, we conducted TRAP analysis of the two major classes of these neurons: dSPNs that express the dopamine receptor 1a (Drd1a), and iSPNs that express the dopamine receptor 2 (Drd2). To disrupt dopamine innervation to both of these SPN populations that reside in the striatum, we injected the neurotoxin 6-hydroxydopamine (6-OHDA), unilaterally, in the medial forebrain bundle (MFB) in hemizygous Drd1-TRAP and Drd2-TRAP adult (9-14 weeks) male mice (kept on a C57BL/6J genetic background). This lesion procedure causes nigral dopamine cell death within a few days, along with a widespread and near-complete loss of dopaminergic innervation to the entire dorsal striatum on one side of the brain (a hemiparkinsonian model). We first examined the effects of dopamine depletion alone, compared to a mock lesion (ascorbate / saline injected). We then examined the effects of chronic levodopa treatment upon the molecular profiles of dopamine- depleted dSPNs and iSPNs, with two dose regimens. The ‘high-dose’ L-DOPA regimen (3 mg/kg on days 1-3, followed by 6 mg/kg on days 4-9) was expected to induce severe dyskinesia in all MFB-lesioned mice. The low-dose L-DOPA regimen (1 mg/kg on days 1-3, followed by 2 mg/kg on days 4-9) was expected to reverse limb use asymmetry without causing conspicuous dyskinesias. To equalize the effects of stress and handling across all groups, including control groups, all mice were equally handled and thus received saline injections when not receiving levodopa injections. Each treatment group contained 7-10 replicates. TRAP-purified mRNAs from either Drd1a- or Drd2-expressing SPNs were reverse-transcribed, amplified, and used to interrogate Affymetrix 430_2.0 GeneChip microarrays.

Project description:Levodopa-induced dyskinesia (LID) is a persistent behavioral sensitization that develops after repeated levodopa (L-DOPA) exposure in Parkinson disease (PD) patients. we used reduced representation bisulfite sequencing to determine the methylation status of cytosines genome wide at base pair resolution following a parkinsonian-like lesion and LID development. Due to the enrichment of RRBS, we focused our analysis to cytosines in a CpG context and observed extensive locus-specific changes in DNA methylation, including a preponderance of demethylation, in the dorsal striatum following the development of dyskinetic behaviors in our animal model system. Changes in DNA methylation were concentrated in putative regulatory regions of many genes known to be aberrantly transcribed following L-DOPA exposure and enriched for genes relevant to mechanisms of synaptic plasticity. In the areas of the genome exhibiting the highest levels of effect, the magnitudes of change to methylation were strongly correlated with dyskinetic behaviors. Rats were given a unilateral dopaminergic lesion to the left medial forebrain bundle with 6-OHDA to destroy at least 90% of TH positive axons. Animals were allowed to recover for 3 weeks and then given daily injections of L-DOPA (6 mg/kg) for seven days to establish stable dyskinesia. Animals were sacked 3 hrs following the final L-DOPA injection and the dorsal striatum was immediately dissected and flash frozen. Striatal tissue samples were processed for nucleic acid isolation using the AllPrep DNA/RNA Mini Kit (Qiagen) following the manufacturer's instructions. One Î¼g of gDNA sample was used for library construction. Bisulfite converted DNA libraries were produced and adaptor ligated, and single-end reads were sequenced on an Illumina HiSeq-2500 following library QC. Bisulfite conversion efficiency was greater that 98% for all of the samples and we obtained an average of 68 million reads per library. Quality control on raw reads was performed with FastQC (version 0.10.1, http://www.bioinformatics.bbsrc.ac.uk/projects/fastqc), and adaptor trimming and removal of trimmed reads shorter than 20 bp was performed with Trim Galore (version 0.3.7, http://www.bioinformatics.babraham.ac.uk/projects/trim_galore). Trimmed reads were mapped to the UCSC Rattus norvegicus rn5 genome with the methylation-aware mapper bismark (version 0.13.0). Samtools (version 0.1.19â??96b5f2294a) was used to sort SAM files produced by bismark and de-duplicate reads. SAM files were analyzed using MethylKit (version 0.9.2) in R (Akalin et al., 2012). Reads were filtered based on coverage, with a cutoff of at least ten reads per site, and normalized for each samples coverage before analysis. The genome was tiled at 250 bp and regions were counted if they contained at least 2 identified CpGs per tile. Differential methylation was defined as a sliding linear model correct p-value of <0.01 and, for highly dynamic regions, included at least a 5% change.

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Riluzole administration to rats with levodopa-induced dyskinesia analyzed by RRBS

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