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Sökning: WFRF:(Bezard Erwan) > (2010-2014)

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1.
  • Bezard, Erwan, et al. (författare)
  • Animal Models of Parkinson's Disease: Limits and Relevance to Neuroprotection Studies
  • 2013
  • Ingår i: Movement Disorders. - : John Wiley & Sons Inc.. - 0885-3185. ; 28:1, s. 61-70
  • Forskningsöversikt (refereegranskat)abstract
    • Over the last two decades, significant strides has been made toward acquiring a better knowledge of both the etiology and pathogenesis of Parkinson's disease (PD). Experimental models are of paramount importance to obtain greater insights into the pathogenesis of the disease. Thus far, neurotoxin-based animal models have been the most popular tools employed to produce selective neuronal death in both in vitro and in vivo systems. These models have been commonly referred to as the pathogenic models. The current trend in modeling PD revolves around what can be called the disease gene-based models or etiologic models. The value of utilizing multiple models with a different mechanism of insult rests on the premise that dopamine-producing neurons die by stereotyped cascades that can be activated by a range of insults, from neurotoxins to downregulation and overexpression of disease-related genes. In this position article, we present the relevance of both pathogenic and etiologic models as well as the concept of clinically relevant designs that, we argue, should be utilized in the preclinical development phase of new neuroprotective therapies before embarking into clinical trials. (C) 2012 Movement Disorder Society
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2.
  • Bezard, Erwan, et al. (författare)
  • Anti-dyskinetic effect of anpirtoline in animal models of L-DOPA-induced dyskinesia
  • 2013
  • Ingår i: Neuroscience Research. - : Elsevier. - 0168-0102. ; 77:4, s. 242-246
  • Tidskriftsartikel (refereegranskat)abstract
    • The serotonin system has emerged as a potential target for anti-dyskinetic therapy in Parkinson's disease. In fact, serotonin neurons can convert L-DOPA into dopamine, and mediate its synaptic release. However, they lack a feedback control mechanism able to regulate synaptic dopamine levels, which leads to un-physiological stimulation of post-synaptic striatal dopamine receptors. Accordingly, drugs able to dampen the activity of serotonin neurons can suppress L-DOPA-induced dyskinesia in animal models of Parkinson's disease. Here, we investigated the ability of the 5-HT1A/1B receptor agonist anpirtoline to counteract LDOPA-induced dyskinesia in L-DOPA-primed 6-OHDA-lesioned rats and MPTP-treated macaques. Results suggest that anpirtoline dose-dependently reduced dyskinesia both in rats and monkeys; however, the effect in MPTP-treated macaques was accompanied by a worsening of the Parkinson's disease score at significantly effective doses (1.5 and 2.0 mg/kg). At a lower dose (0.75 mg/ kg), anpirtoline markedly reduced dyskinesia in 4 out of 5 subjects, but statistical significance was prevented by the presence of a non-responsive subject. These results provide further evidence that the serotonin neurons contribute both to the pro-dyskinetic effect of L-DOPA and to its therapeutic efficacy in the rat and monkey models of Parkinson's disease. (c) 2013 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.
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3.
  • Bezard, Erwan, et al. (författare)
  • Study of the antidyskinetic effect of eltoprazine in animal models of levodopa-induced dyskinesia
  • 2013
  • Ingår i: Movement Disorders. - : John Wiley & Sons Inc.. - 0885-3185. ; 28:8, s. 1088-1096
  • Tidskriftsartikel (refereegranskat)abstract
    • The serotonin (5-hydroxytryptamine [5HT]) system has recently emerged as an important player in the appearance of l-3,4-dihydroxyphenylalanine (levodopa [l-dopa])-induced dyskinesia in animal models of Parkinson's disease. In fact, dopamine released as a false transmitter from serotonin neurons appears to contribute to the pulsatile stimulation of dopamine receptors, leading to the appearance of the abnormal involuntary movements. Thus, drugs able to dampen the activity of serotonin neurons hold promise for the treatment of dyskinesia. The authors investigated the ability of the mixed 5-HT 1A/1B receptor agonist eltoprazine to counteract l-dopa-induced dyskinesia in 6-hydroxydopamine-lesioned rats and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated macaques. The data demonstrated that eltoprazine is extremely effective in suppressing dyskinesia in experimental models, although this effect was accompanied by a partial worsening of the therapeutic effect of l-dopa. Interestingly, eltoprazine was found to (synergistically) potentiate the antidyskinetic effect of amantadine. The current data indicated that eltoprazine is highly effective in counteracting dyskinesia in preclinical models. However, the partial worsening of the l-dopa effect observed after eltoprazine administration represents a concern; whether this side effect is due to a limitation of the animal models or to an intrinsic property of eltoprazine needs to be addressed in ongoing clinical trials. The data also suggest that the combination of low doses of eltoprazine with amantadine may represent a valid strategy to increase the antidyskinetic effect and reduce the eltoprazine-induced worsening of l-dopa therapeutic effects. (c) 2013 Movement Disorder Society
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4.
  • Bourdenx, Mathieu, et al. (författare)
  • Abnormal structure-specific peptide transmission and processing in a primate model of Parkinson's disease and L-DOPA-induced dyskinesia
  • 2014
  • Ingår i: Neurobiology of Disease. - 0969-9961 .- 1095-953X. ; 62, s. 307-312
  • Tidskriftsartikel (refereegranskat)abstract
    • A role for enhanced peptidergic transmission, either opioidergic or not, has been proposed for the generation of L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) on the basis of in situ hybridization studies showing that striatal peptidergic precursor expression consistently correlates with LID severity. Few studies, however, have focused on the actual peptides derived from these precursors. We used mass-spectrometry to study peptide profiles in the putamen and globus pallidus (internalis and externalis) collected from 1-methyl-4-phenyl-1,2,4,6-tetrahydropyridine treated macaque monkeys, acutely or chronically treated with L-DOPA. We identified that parkinsonian and dyskinetic states are associated with an abnormal production of proenkephalin-, prodynorphin- and protachykinin-1-derived peptides in both segments of the globus pallidus. Moreover, we report that peptidergic processing is dopamine-state dependent and highly structure-specific, possibly explaining the failure of previous clinical trials attempting to rectify abnormal peptidergic transmission.
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5.
  • Fasano, Stefania, et al. (författare)
  • Inhibition of Ras-guanine nucleotide-releasing factor 1 (Ras-GRF1) signaling in the striatum reverts motor symptoms associated with L-dopa-induced dyskinesia.
  • 2010
  • Ingår i: Proceedings of the National Academy of Sciences. - : National Academy of Sciences. - 1091-6490. ; 107, s. 21824-21829
  • Tidskriftsartikel (refereegranskat)abstract
    • l-dopa-induced dyskinesia (LID) is a common debilitating complication of dopamine replacement therapy in Parkinson's disease. Recent evidence suggests that LID may be linked causally to a hyperactivation of the Ras-ERK signaling cascade in the basal ganglia. We set out to determine whether specific targeting of Ras-guanine nucleotide-releasing factor 1 (Ras-GRF1), a brain-specific activator of the Ras-ERK pathway, may provide a therapy for LID. On the rodent abnormal involuntary movements scale, Ras-GRF1-deficient mice were significantly resistant to the development of dyskinesia during chronic l-dopa treatment. Furthermore, in a nonhuman primate model of LID, lentiviral vectors expressing dominant negative forms of Ras-GRF1 caused a dramatic reversion of dyskinesia severity leaving intact the therapeutic effect of l-dopa. These data reveal the central role of Ras-GRF1 in governing striatal adaptations to dopamine replacement therapy and validate a viable treatment for LID based on intracellular signaling modulation.
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6.
  • Rylander, Daniella, et al. (författare)
  • A mGluR5 antagonist under clinical development improves L-DOPA-induced dyskinesia in parkinsonian rats and monkeys.
  • 2010
  • Ingår i: Neurobiology of Disease. - : Elsevier. - 0969-9961. ; 39, s. 352-361
  • Tidskriftsartikel (refereegranskat)abstract
    • L-DOPA remains the gold-standard treatment for Parkinson's disease but causes motor fluctuations and dyskinesia. Metabotropic glutamate receptor type 5 (mGluR5) has been proposed as a target for antidyskinetic therapies. Here, we evaluate the effects of fenobam, a noncompetitive mGluR5 antagonist already tested in humans, using rodent and nonhuman primate models of L-DOPA-induced dyskinesia. In both animal models, acute administration of fenobam attenuated the L-DOPA-induced abnormal involuntary movements (50-70% reduction at the doses of 30mg/kg in rats and 10mg/kg in monkeys). The effect consisted in a reduction of peak-dose dyskinesia, whereas the end-dose phase was not affected. Chronic administration of fenobam to previously drug-naïve animals (de novo treatment) attenuated the development of peak-dose dyskinesia without compromising the anti-parkinsonian effect of L-DOPA. In addition, fenobam prolonged the motor stimulant effect of L-DOPA. We conclude that fenobam acts similarly in rat and primate models of L-DOPA-induced dyskinesia and that it represents a good candidate for antidyskinetic treatment in Parkinson's disease.
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7.
  • Rylander, Daniella, et al. (författare)
  • Maladaptive plasticity of serotonin axon terminals in levodopa-induced dyskinesia.
  • 2010
  • Ingår i: Annals of Neurology. - : John Wiley & Sons Inc.. - 1531-8249. ; 68:5, s. 619-628
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE:: Striatal serotonin projections have been implicated in levodopa-induced dyskinesia by providing an unregulated source of dopamine release. We set out to determine whether these projections are affected by levodopa treatment in a way that would favor the occurrence of dyskinesia. METHODS:: As an index of terminal serotonin innervation density, we measured radioligand binding to the plasma membrane serotonin transporter (SERT) in levodopa-treated dyskinetic and nondyskinetic subjects, using brain tissue from both rat and monkey models of Parkinson disease as well as parkinsonian patients. In addition, striatal tissue from dyskinetic rats was used for morphological and ultrastructural analyses of serotonin axon terminals, and for studies of stimulated [(3)H]dopamine release. RESULTS:: Across all conditions examined, striatal levels of SERT radioligand binding were significantly elevated in dyskinetic subjects compared to nondyskinetic cases. In the rat striatum, dyskinesiogenic levodopa treatment had induced sprouting of serotonin axon varicosities having a relatively high synaptic incidence. This response was associated with increased depolarization-induced [(3)H]dopamine release and with a stronger release potentiation by brain-derived neurotrophic factor. INTERPRETATION:: This study provides the first evidence that L-dopa treatment induces sprouting of serotonin axon terminals, with an increased incidence of synaptic contacts, and a larger activity-dependent potentiation of dopamine release in the dopamine-denervated striatum. Treatment-induced plasticity of the serotonin innervation may therefore represent a previously unappreciated cause of altered dopamine dynamics. These results are important for understanding the mechanisms by which L-dopa pharmacotherapy predisposes to dyskinesia, and for defining biomarkers of motor complications in Parkinsons disease. Ann Neurol 2010.
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8.
  • Shariatgorji, Mohammadreza, et al. (författare)
  • Direct targeted quantitative molecular imaging of neurotransmitters in brain tissue sections
  • 2014
  • Ingår i: Neuron. - 0896-6273 .- 1097-4199. ; 84:4, s. 697-707
  • Tidskriftsartikel (refereegranskat)abstract
    • Current neuroimaging techniques have very limited abilities to directly identify and quantify neurotransmitters from brain sections. We have developed a molecular-specific approach for the simultaneous imaging and quantitation of multiple neurotransmitters, precursors, and metabolites, such as tyrosine, tryptamine, tyramine, phenethylamine, dopamine, 3-methoxytyramine, serotonin, GABA, glutamate, acetylcholine, and L-alpha-glycerylphosphorylcholine, in histological tissue sections at high spatial resolutions. The method is employed to directly measure changes in the absolute and relative levels ofneurotransmitters in specific brain structures in animal disease models and in response to drug treatments, demonstrating the power of mass spectrometry imaging in neuroscience.
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