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Dopamine D2 receptor activation inhibits choroidal neovascularization in Parkinson patients with age related macular degeneration.

ABSTRACT: Neovascular age-related macular degeneration (nAMD) remains a major cause of visual impairment and puts considerable burden on patients and health care systems. L-DOPA-treated Parkinson Disease (PD) patients have been shown to be partially protected from nAMD, but the mechanism remains unknown. Using murine models combining 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD and laser-induced nAMD, standard PD treatment of L-DOPA/DOPA-decarboxylase inhibitor, or specific dopamine receptor inhibitors, we here demonstrate that L-DOPA treatment-induced increase of dopamine receptor D2 (DRD2) signaling inhibits choroidal neovascularization independently of MPTP-associated nigrostriatal pathway lesion. Analyzing a retrospective cohort of more than two hundred thousand nAMD patients receiving anti-VEGF treatment from the French nationwide insurance database, we show that DRD2-agonist treated (PD) patients have a significantly delayed age of onset for nAMD (81.4 (±7.0) vs 79.4 (±8.1) years old, respectively, p<0.0001) and reduced need for anti-VEGF therapies (-0.6 injections per 100 mg/day daily dose of DRD2 agonists the second year of treatment), similar to the L-DOPA treatment. While providing a mechanistic explanation for an intriguing epidemiological observation, our findings suggest that systemic DRD2 agonists might constitute an adjuvant therapy to delay and reduce the need for anti-VEGF therapy in nAMD patients.

ORGANISM(S): Mus musculus

PROVIDER: GSE266525 | GEO | 2024/09/13

REPOSITORIES: GEO

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Project description:The therapeutic benefits of L–3,4–dihydroxyphenylalanine (L-DOPA) in Parkinson’s disease (PD) patients severely diminishes with the onset of L-DOPA-induced dyskinesia (LID), a debilitating motor side effect. LID is mainly due to altered dopaminergic signaling in the striatum, a brain region that controls motor and cognitive functions. However, the molecular mechanisms that promote LID remain unclear. Here, we have reported that increased striatal RasGRP1 (also known as CalDAG-GEF-II) is instrumentally linked to the development of LID in a 6-hydroxydopamine (6-OHDA) lesioned mouse model of PD. L-DOPA treatment rapidly upregulated RasGRP1 in the dopamine-1 receptor positive neurons in the dorsal striatum. RasGRP1 deleted mice (RasGRP1–/–) had drastically diminished LID, and RasGRP1–/– mice did not interfere with the therapeutic benefits of L-DOPA. In terms of its mechanism, RasGRP1 mediated L-DOPA-induced extracellular regulated kinase (ERK), the mammalian target of rapamycin kinase (mTOR) and the cAMP/PKA pathway. RasGRP1 bind directly with and acts 2 as a guanine nucleotide exchange (GEF) for Ras-homolog-enriched in the brain (Rheb), a potent activator of mTOR, both in vitro and in the intact striatum. High-resolution tandem mass tag mass spectrometry analysis of striatal tissue revealed significant targets, such as phosphodiesterase 10a (Pde10a), Pde2a, catechol-o-methyltransferase (Comt), and glutamate decarboxylase 1 and 2 (Gad1 and Gad2), as downstream regulators of RasGRP1 that are linked to LID vulnerability. Moreover, we found that RASGRP1 protein is also upregulated predominantly in the striatum of MPTP-lesioned macaque treated with L-DOPA, emphasizing the translational potential of this protein. Collectively, the findings of this study demonstrated that RasGRP1 is a major regulator of LID in the dorsal striatum. Pharmacological or gene-depletion strategies targeting RasGRP1 may offer novel therapeutic opportunities for preventing LID in PD patients.

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.

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Dopamine D2 receptor activation inhibits choroidal neovascularization in Parkinson patients with age related macular degeneration.

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