| 1. |
- Ohlin, Elisabet, et al.
(författare)
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Vascular endothelial growth factor is upregulated by L-dopa in the parkinsonian brain: implications for the development of dyskinesia.
- 2011
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 134, s. 2339-2357
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Tidskriftsartikel (refereegranskat)abstract
- Angiogenesis and increased permeability of the blood-brain barrier have been reported to occur in animal models of Parkinson's disease and l-dopa-induced dyskinesia, but the significance of these phenomena has remained unclear. Using a validated rat model of l-dopa-induced dyskinesia, this study demonstrates that chronic treatment with l-dopa dose dependently induces the expression of vascular endothelial growth factor in the basal ganglia nuclei. Vascular endothelial growth factor was abundantly expressed in astrocytes and astrocytic processes in the proximity of blood vessels. When co-administered with l-dopa, a small molecule inhibitor of vascular endothelial growth factor signalling significantly attenuated the development of dyskinesia and completely blocked the angiogenic response and associated increase in blood-brain barrier permeability induced by the treatment. The occurrence of angiogenesis and vascular endothelial growth factor upregulation was verified in post-mortem basal ganglia tissue from patients with Parkinson's disease with a history of dyskinesia, who exhibited increased microvascular density, microvascular nestin expression and an upregulation of vascular endothelial growth factor messenger ribonucleic acid. These congruent findings in the rat model and human patients indicate that vascular endothelial growth factor is implicated in the pathophysiology of l-dopa-induced dyskinesia and emphasize an involvement of the microvascular compartment in the adverse effects of l-dopa pharmacotherapy in Parkinson's disease.
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| 2. |
- Fieblinger, Tim, et al.
(författare)
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Mechanisms of Dopamine D1 Receptor-Mediated ERK1/2 Activation in the Parkinsonian Striatum and Their Modulation by Metabotropic Glutamate Receptor Type 5
- 2014
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Ingår i: Journal of Neuroscience. - : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 34:13, s. 4728-4740
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Tidskriftsartikel (refereegranskat)abstract
- In animal models of Parkinsons disease, striatal overactivation of ERK1/2 via dopamine (DA) D1 receptors is the hallmark of a supersensitive molecular response associated with dyskinetic behaviors. Here we investigate the pathways involved in D1 receptor-dependent ERK1/2 activation using acute striatal slices from rodents with unilateral 6-hydroxydopamine (6-OHDA) lesions. Application of the dopamine D1-like receptor agonist SKF38393 induced ERK1/2 phosphorylation and downstream signaling in the DA-denervated but not the intact striatum. This response was mediated through a canonical D1R/PKA/MEK1/2 pathway and independent of ionotropic glutamate receptors but blocked by antagonists of L-type calcium channels. Coapplication of an antagonist of metabotropic glutamate receptor type 5 (mGluR5) or its downstream signaling molecules (PLC, PKC, IP3 receptors) markedly attenuated SKF38393-induced ERK1/2 activation. The role of striatal mGluR5 in D1-dependent ERK1/2 activation was confirmed in vivo in 6-OHDA-lesioned animals treated systemically with SKF38393. In one experiment, local infusion of the mGluR5 antagonistMTEPin the DA-denervated rat striatum attenuated the activation of ERK1/2 signaling by SKF38393. In another experiment, 6-OHDA lesions were applied to transgenic mice with a cell-specific knockdown of mGluR5 in D1 receptor-expressing neurons. These mice showed a blunted striatal ERK1/2 activation in response to SFK38393 treatment. Our results reveal that D1-dependent ERK1/2 activation in the DA-denervated striatum depends on a complex interaction between PKA-and Ca2+ -dependent signaling pathways that is critically modulated by striatal mGluR5.
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| 3. |
- Francardo, Veronica, et al.
(författare)
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Impact of the lesion procedure on the profiles of motor impairment and molecular responsiveness to L-DOPA in the 6-hydroxydopamine mouse model of Parkinson's disease.
- 2011
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Ingår i: Neurobiology of disease. - : Elsevier BV. - 1095-953X .- 0969-9961. ; 42:3, s. 327-40
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Tidskriftsartikel (refereegranskat)abstract
- 6-Hydroxydopamine (6-OHDA) lesions are being used in the mouse for basic research on Parkinson's disease and L-DOPA-induced dyskinesia. We set out to compare unilateral lesion models produced by intrastriatal or intramesencephalic injections of a fixed 6-OHDA concentration (3.2 μg/μl) in C57BL/6 mice. In the first experiment, toxin injections were performed either at two striatal coordinates (1 or 2 μl per site, termed "striatum(2 × 1 μl)" and "striatum(2 × 2 μl)" models), in the medial forebrain bundle (MFB), or in the substantia nigra pars compacta (SN) (1 μl per site). All the four lesion models produced significant forelimb use asymmetry, but spontaneous turning asymmetry only occurred in the MFB and striatum(2 × 2 μl) models. After the behavioral studies, the induction of phosphorylated extracellular signal-regulated kinases 1 and 2 (pERK1/2) by acute L-DOPA (30 mg/kg) was used as a marker of post-synaptic supersensitivity. Striatal pERK1/2 expression was sparse in the SN and striatum(2 × 1 μl) groups, but pronounced in the striatum(2 × 2 μl) and MFB-lesioned mice. In further experiments, mice with MFB and striatal(2 × 2 μl) lesions were used to compare behavioral and molecular responses to chronic L-DOPA treatment (12 days at 3 and 6 mg/kg/day). Maximally severe abnormal involuntary movements (AIMs) occurred in all MFB-lesioned mice, whereas only 35% of the mice with striatal lesions developed dyskinesia. Striatal tissue levels of dopamine were significantly lower in the dyskinetic animals (both MFB and striatum(2 × 2 μl) groups) in comparison with the non-dyskinetic ones. Noradrenaline levels were significantly reduced only in MFB lesioned animals and did not differ among the dyskinetic and non-dyskinetic cases with striatal lesions. In all groups, the L-DOPA-induced AIM scores correlated closely with the number of cells immunoreactive for tyrosine hydroxylase or FosB/∆FosB in the striatum. In conclusion, among the four lesion procedures examined here, only the MFB and striatum(2 × 2 μl) models yielded a degree of dopamine denervation sufficient to produce spontaneous postural asymmetry and molecular supersensitivity to L-DOPA. Both lesion models are suitable to reproduce L-DOPA-induced dyskinesia, although only MFB lesions yield a pronounced and widespread expression of post-synaptic supersensitivity markers in the striatum.
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| 4. |
- Francardo, Veronica, et al.
(författare)
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Pharmacological stimulation of sigma-1 receptors has neurorestorative effects in experimental parkinsonism
- 2014
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 137, s. 1998-2014
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Tidskriftsartikel (refereegranskat)abstract
- Sigma-1 receptor ligands may have neuroprotective and neurorestorative properties. In a mouse model of parkinsonism, Francardo et al. show that chronic treatment with the sigma-1 receptor agonist PRE-084 increases the density of striatal dopaminergic fibres and improves forelimb use. Boosting sigma-1 receptor activity may have disease-modifying effects in ParkinsonA ' s disease.The sigma-1 receptor, an endoplasmic reticulum-associated molecular chaperone, is attracting great interest as a potential target for neuroprotective treatments. We provide the first evidence that pharmacological modulation of this protein produces functional neurorestoration in experimental parkinsonism. Mice with intrastriatal 6-hydroxydopamine lesions were treated daily with the selective sigma-1 receptor agonist, PRE-084, for 5 weeks. At the dose of 0.3 mg/kg/day, PRE-084 produced a gradual and significant improvement of spontaneous forelimb use. The behavioural recovery was paralleled by an increased density of dopaminergic fibres in the most denervated striatal regions, by a modest recovery of dopamine levels, and by an upregulation of neurotrophic factors (BDNF and GDNF) and their downstream effector pathways (extracellular signal regulated kinases 1/2 and Akt). No treatment-induced behavioural-histological restoration occurred in sigma-1 receptor knockout mice subjected to 6-hydroxydopamine lesions and treated with PRE-084. Immunoreactivity for the sigma-1 receptor protein was evident in both astrocytes and neurons in the substantia nigra and the striatum, and its intracellular distribution was modulated by PRE-084 (the treatment resulted in a wider intracellular distribution of the protein). Our results suggest that sigma-1 receptor regulates endogenous defence and plasticity mechanisms in experimental parkinsonism. Boosting the activity of this protein may have disease-modifying effects in Parkinson's disease.
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| 5. |
- Francardo, Veronica, et al.
(författare)
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Preclinical models of levodopa-induced dyskinesia
- 2014
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Ingår i: Levodopa-Induced Dyskinesia in Parkinson's Disease. - London : Springer London. - 1447165020 - 9781447165026 - 9781447165033 ; , s. 335-353
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Bokkapitel (refereegranskat)abstract
- L -DOPA-induced dyskinesia (LID) represents one of the major limitations in the current pharmacotherapy of Parkinson's disease (PD) and affects the majority of PD patients. Animal models are the most important preclinical tool for molecular investigations of LID mechanisms and therapeutic targets. Over the last two decades, models of LID have been developed in both nonhuman primate and rodent species, recapitulating several aspects of the human dyskinesia. This chapter will review and compare the main features of the rodent and nonprimate models of LID currently available and summarize some of the main neurobiological fi ndings obtained from these models.
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| 6. |
- Lindgren, Hanna, et al.
(författare)
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L-DOPA-induced dopamine efflux in the striatum and the substantia nigra in a rat model of Parkinson's disease: temporal and quantitative relationship to the expression of dyskinesia.
- 2010
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Ingår i: Journal of neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 112:6, s. 1465-76
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Tidskriftsartikel (refereegranskat)abstract
- Abstract L-DOPA-induced dyskinesia in Parkinson's Disease (PD) is associated with large increases in brain dopamine (DA) levels following drug dosing, but the precise significance of this phenomenon is not understood. Here we compare DA efflux and metabolism in the striatum and the substantia nigra (SN) in dyskinetic and non-dyskinetic animals following a standard dose of L-DOPA. Rats with 6-OHDA lesions were treated chronically with L-DOPA, monitored on the abnormal involuntary movements (AIMs) scale, and then subjected to intracerebral microdialysis under freely-moving conditions. Following s.c. L-DOPA injection, peak extracellular DA levels in both striatum and SN were twice as large in dyskinetic animals compared to non-dyskinetic rats. This effect was not attributable to differences in DOPA levels or DA metabolism. The larger DA efflux in dyskinetic animals was blunted by 5-HT1A/5-HT1B receptor agonists and TTX infusion, reflecting release from serotonin neurons. Striatal levels of serotonin and its main metabolite, 5-hydroxyindolacetic acid were indeed elevated in dyskinetic animals compared to non-dyskinetic rats, indicating a larger serotonergic innervation density in the former group. High DA release was, however, not sufficient to explain dyskinesia. The AIMs output per unit concentration of striatal extracellular DA was indeed much larger in dyskinetic animals compared to non-dyskinetic cases at most time points examined. The present results indicate that both a high DA release post L-DOPA administration and an increased responsiveness to DA must coexist for a full expression of dyskinesia.
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| 7. |
- Fieblinger, Tim, et al.
(författare)
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Cell type-specific plasticity of striatal projection neurons in parkinsonism and L-DOPA-induced dyskinesia.
- 2014
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- The striatum is widely viewed as the fulcrum of pathophysiology in Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID). In these disease states, the balance in activity of striatal direct pathway spiny projection neurons (dSPNs) and indirect pathway spiny projection neurons (iSPNs) is disrupted, leading to aberrant action selection. However, it is unclear whether countervailing mechanisms are engaged in these states. Here we report that iSPN intrinsic excitability and excitatory corticostriatal synaptic connectivity were lower in PD models than normal; L-DOPA treatment restored these properties. Conversely, dSPN intrinsic excitability was elevated in tissue from PD models and suppressed in LID models. Although the synaptic connectivity of dSPNs did not change in PD models, it fell with L-DOPA treatment. In neither case, however, was the strength of corticostriatal connections globally scaled. Thus, SPNs manifested homeostatic adaptations in intrinsic excitability and in the number but not strength of excitatory corticostriatal synapses.
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| 8. |
- Francardo, Veronica, et al.
(författare)
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Investigating the molecular mechanisms of L-DOPA-induced dyskinesia in the mouse
- 2014
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Ingår i: Parkinsonism and Related Disorders. - 1353-8020. ; 20:SUPPL.1, s. 20-22
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Tidskriftsartikel (refereegranskat)abstract
- L-DOPA-induced dyskinesia (LID) is a major complication of the pharmacotherapy of Parkinson's disease (PD). Animal models of LID are essential for investigating pathogenic pathways and therapeutic targets. While non-human primates have been the preferred species for pathophysiological studies, mouse models of LID have been recently produced and characterized to facilitate molecular investigations. Most of these studies have used mice with unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal projection sustaining treatment with L-DOPA for 1-4 weeks. Mice with complete medial forebrain bundle lesions have been found to develop dyskinetic movements of maximal severity associated with a pronounced post-synaptic supersensitivity of D1-receptor dependent signaling pathways throughout the striatum. In contrast, mice with striatal 6-OHDA lesions have been found to exhibit a variable susceptibility to LID and a regionally restricted post-synaptic supersensitivity. Genetic mouse models of PD have just started to be used for studies of LID, providing an opportunity to dissect the impact of genetic factors on the maladaptive neuroplasticity that drives the development of treatment-induced involuntary movements in PD.
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| 9. |
- Lindgren, Hanna, et al.
(författare)
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Putaminal Upregulation of FosB/Delta FosB-Like Immunoreactivity in Parkinson's Disease Patients with Dyskinesia
- 2011
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Ingår i: Journal of Parkinson's Disease. - 1877-718X. ; 1:4, s. 347-357
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor Delta FosB is a mediator of maladaptive neuroplasticity in animal models of Parkinson's disease (PD) and L-DOPA-induced dyskinesia. Using an antibody that recognizes all known isoforms of FosB and Delta FosB, we have examined the expression of these proteins in post-mortem basal ganglia sections from PD patients. The patient cases were classified as being dyskinetic or non-dyskinetic based on their clinical records. Sections from neurologically healthy controls were also included in the study. Compared to both controls and non-dyskinetic cases, the dyskinetic group showed a higher density of FosB/Delta FosB-immunopositive cells in the posterior putamen, which represents the motor region of the striatum in primates. In contrast, the number of FosB/Delta FosB-positive cells did not differ significantly among the groups in the caudate, a region primarily involved with the processing of cognitive and limbic-related information. Only sparse FosB/Delta FosB immunoreactivity was found in the in the pallidum externum and internum, and no significant group differences were detected in these nuclei. The putaminal elevation of FosB/Delta FosB-like immunoreactivity in patients who had been affected by L-DOPA-induced dyskinesia is consistent with results from both rat and non-human primate models of this movement disorder. The present findings support the hypothesis of an involvement of Delta FosB-related transcription factors in the molecular mechanisms of L-DOPA-induced dyskinesia.
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| 10. |
- Lindgren, Hanna S., et al.
(författare)
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Dyskinesia - Advances in the understanding of pathophysiology and possible treatment options
- 2010
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Ingår i: European Neurological Review. - 1758-3837. ; 5:2, s. 34-40
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Tidskriftsartikel (refereegranskat)abstract
- The degeneration of nigrostriatal dopaminergic neurons in Parkinson's disease gives rise to tremor and slowness of movement, cardinal motor symptoms of the disease that can be alleviated by the dopamine precursor L-DOPA. Despite this, long-term L-DOPA treatment is hampered by the development of abnormal involuntary movements, i.e. dyskinesia, in the majority of patients. The pathophysiology of dyskinesia is complex and multifactorial, but excessive swings in extracellular dopamine causing aberrant plasticity in dopaminoceptive neurons are attributed a primary role. To date there are few effective treatment alternatives for patients with Parkinson's disease experiencing dyskinesia, representing an unmet therapeutic need in the treatment strategy of the disease. This article reviews recent findings from both clinical and pre-clinical studies and their impact on the search for novel therapeutic approaches to levodopa-induced dyskinesia.
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