| 1. |
- Decressac, Mickael, et al.
(författare)
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GDNF fails to exert neuroprotection in a rat {alpha}-synuclein model of Parkinson's disease.
- 2011
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Ingår i: Brain. - : Oxford University Press (OUP). - 1460-2156 .- 0006-8950. ; 134:8, s. 2302-2311
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Tidskriftsartikel (refereegranskat)abstract
- The neuroprotective effect of the glial cell line-derived neurotrophic factor has been extensively studied in various toxic models of Parkinson's disease. However, it remains unclear whether this neurotrophic factor can protect against the toxicity induced by the aggregation-prone protein α-synuclein. Targeted overexpression of human wild-type α-synuclein in the nigrostriatal system, using adeno-associated viral vectors, causes a progressive degeneration of the nigral dopamine neurons and the development of axonal pathology in the striatum. In the present study, we investigated, using different paradigms of delivery, whether glial cell line-derived neurotrophic factor can protect against the neurodegenerative changes and the cellular stress induced by α-synuclein. We found that viral vector-mediated delivery of glial cell line-derived neurotrophic factor into substantia nigra and/or striatum, administered 2-3 weeks before α-synuclein, was inefficient in preventing the wild-type α-synuclein-induced loss of dopamine neurons and terminals. In addition, glial cell line-derived neurotrophic factor overexpression did not ameliorate the behavioural deficit in this rat model of Parkinson's disease. Quantification of striatal α-synuclein-positive aggregates revealed that glial cell line-derived neurotrophic factor had no effect on α-synuclein aggregation. These data provide the evidence for the lack of neuroprotective effect of glial cell line-derived neurotrophic factor against the toxicity of human wild-type α-synuclein in an in vivo model of Parkinson's disease. The difference in neuroprotective efficacy of glial cell line-derived neurotrophic factor seen in our model and the commonly used neurotoxin models of Parkinson's disease, raises important issues pertinent to the interpretation of the results obtained in preclinical models of Parkinson's disease, and their relevance for the therapeutic use glial cell line-derived neurotrophic factor in patients with Parkinson's disease.
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| 2. |
- Ericson, Cecilia, et al.
(författare)
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Ex vivo gene delivery of GDNF using primary astrocytes transduced with a lentiviral vector provides neuroprotection in a rat model of Parkinson's disease.
- 2005
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 22:11, s. 2755-2764
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Tidskriftsartikel (refereegranskat)abstract
- Astrocytes are, as normal constituents of the brain, promising vehicles for ex vivo gene delivery to the central nervous system. In the present study, we have used a lentiviral vector encoding glial cell line-derived neurotrophic factor (GDNF) to transduce rat-derived primary astrocytes, in order to evaluate their potential for long-term transgene expression in vivo and neuroprotection in a rat model of Parkinson's disease. Following transplantation of GDNF-transduced astrocytes to the intact striatum, the level of released GDNF was 2.93 +/- 0.28 ng/mg tissue at 1 week post-grafting, reduced to 0.42 +/- 0.12 ng/mg tissue at 4 weeks, and thereafter was maintained at this level throughout the experiment (12 weeks; 0.53 +/- 0.068 ng/mg tissue). Similarly, grafting to the substantia nigra (SN) resulted in a significant overexpression of GDNF ( approximately 0.20 ng/mg tissue) at 1 week. Intact animals receiving transplants of GDNF-transduced astrocytes displayed an increased contralateral turning (5.39 +/- 1.19 turns/min) in the amphetamine-induced rotation test, which significantly correlated with the GDNF tissue levels measured in the striatum, indicating a stimulatory effect of GDNF on the dopaminergic function. Transplantation of GDNF-transduced astrocytes to the SN 1 week prior to an intrastriatal 6-hydroxydopamine lesion provided a significant protection of nigral tyrosine hydroxylase-positive cells. By contrast, when the cells were transplanted to the striatum, the level of released GDNF was not sufficient to rescue the striatal fibers and, hence, to protect the nigral dopaminergic neurons. Overall, our results suggest that genetically modified astrocytes expressing GDNF can provide neuroprotection in a rat model of Parkinson's disease following transplantation to the SN.
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| 3. |
- Eslamboli, A, et al.
(författare)
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Continuous low-level glial cell line-derived neurotrophic factor delivery using recombinant adeno-associated viral vectors provides neuroprotection and induces behavioral recovery in a primate model of Parkinson's disease
- 2005
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 25:4, s. 769-777
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Tidskriftsartikel (refereegranskat)abstract
- The therapeutic potential of glial cell line-derived neurotrophic factor ( GDNF) for Parkinson's disease is likely to depend on sustained delivery of the appropriate amount to the target areas. Recombinant adeno-associated viral vectors ( rAAVs) expressing GDNF may be a suitable delivery system for this purpose. The aim of this study was to define a sustained level of GDNF that does not affect the function of the normal dopamine (DA) neurons but does provide anatomical and behavioral protection against an intrastriatal 6-hydroxydopamine (6-OHDA) lesion in the common marmoset. We found that unilateral intrastriatal injection of rAAV resulting in the expression of high levels of GDNF ( 14 ng/mg of tissue) in the striatum induced a substantial bilateral increase in tyrosine hydroxylase protein levels and activity as well as in DA turnover. Expression of low levels of GDNF (0.04 ng/mg of tissue), on the other hand, produced only minimal effects on DA synthesis and only on the injected side. In addition, the low level of GDNF provided similar to 85% protection of the nigral DA neurons and their projections to the striatum in the 6-OHDA-lesioned hemisphere. Furthermore, the anatomical protection was accompanied by a complete attenuation of sensorimotor neglect, head position bias, and amphetamine-induced rotation. We conclude that when delivered continuously, a low level of GDNF in the striatum ( approximately threefold above baseline) is sufficient to provide optimal functional outcome.
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| 4. |
- Georgievska, Biljana, et al.
(författare)
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Aberrant sprouting and downregulation of tyrosine hydroxylase in lesioned nigrostriatal dopamine neurons induced by long-lasting overexpression of glial cell line derived neurotrophic factor in the striatum by lentiviral gene transfer.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 177:2, s. 461-474
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Tidskriftsartikel (refereegranskat)abstract
- The effects of sustained (up to 9 months) striatal overexpression of glial cell line derived neurotrophic factor (GDNF) on lesioned nigrostriatal dopamine (DA) neurons was studied using a recombinant lentiviral (rLV) vector to deliver GDNF into the striatum 4 weeks prior to the creation of an intrastriatal 6-hydroxydopamine lesion. The results of the amphetamine-induced rotation suggested an initial partial protection followed by a complete recovery, whereas the spontaneous motor behaviors remained impaired. There was a clear protection of the nigral tyrosine hydroxylase (TH)-positive neurons in the rLV-GDNF group compared to rats injected with the control vector encoding green fluorescent protein (GFP) (70 and 20% of the intact side, respectively). However, the striatal TH+ fiber density was equally reduced (to 20% of the intact side) in both groups. Further morphological analyses indicated that the nigrostriatal projections of the DA neurons were indeed preserved in the GDNF group. The axonal projections were visualized using two independent methods: First, retrograde labeling of the nigral cell bodies by intrastriatal Fluoro-Gold injections showed that the majority of rescued cells in the GDNF group had preserved axonal projections to striatum. Second, injections of a recombinant adeno-associated viral vector expressing GFP into the nigra was used to anterogradely fill the DA neurons and their projections with GFP protein. GFP immunostaining clearly demonstrated that the fibers of the nigral DA cells were preserved along the nigrostriatal pathway and innervated large parts of the striatum, but did not express TH at detectable levels. In addition, fiber sprouting was observed in the globus pallidus, entopeduncular nucleus, and substantia nigra, corresponding to areas where GDNF protein was released. The lack of functional recovery in the spontaneous motor behaviors may, at least in part, be explained by this extensive aberrant fiber sprouting in the downstream striatal target nuclei and/or decreased synthesis of dopamine in the striatum.
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| 5. |
- Georgievska, Biljana, et al.
(författare)
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Dissociation between short-term increased graft survival and long-term functional improvements in Parkinsonian rats overexpressing glial cell line-derived neurotrophic factor.
- 2004
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 20:11, s. 3121-3130
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Tidskriftsartikel (refereegranskat)abstract
- The present study was designed to analyse whether continuous overexpression of glial cell line-derived neurotrophic factor (GDNF) in the striatum by a recombinant lentiviral vector can provide improved cell survival and additional long-term functional benefits after transplantation of fetal ventral mesencephalic cells in Parkinsonian rats. A four-site intrastriatal 6-hydroxydopamine lesion resulted in an 80–90% depletion of nigral dopamine cells and striatal fiber innervation, leading to stable motor impairments. Histological analysis performed at 4 weeks after grafting into the GDNF-overexpressing striatum revealed a twofold increase in the number of surviving tyrosine hydroxylase (TH)-positive cells, as compared with grafts placed in control (green fluorescent protein-overexpressing) animals. However, in animals that were allowed to survive for 6 months, the numbers of surviving TH-positive cells in the grafts were equal in both groups, suggesting that the cells initially protected at 4 weeks failed to survive despite the continued presence of GDNF. Although cell survival was similar in both grafted groups, the TH-positive fiber innervation density was lower in the GDNF-treated grafted animals (30% of normal) compared with animals with control grafts (55% of normal). The vesicular monoamine transporter-2-positive fiber density in the striatum, by contrast, was equal in both groups, suggesting that long-term GDNF overexpression induced a selective down-regulation of TH in the grafted dopamine neurons. Behavioral analysis in the long-term grafted animals showed that the control grafted animals improved their performance in spontaneous motor behaviors to approximately 50% of normal, whereas the GDNF treatment did not provide any additional recovery.
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| 6. |
- Georgievska, Biljana
(författare)
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GDNF gene delivery in an animal model of Parkinson's disease. Long-term effects on intact, injured and transplanted dopamine neurons using lentiviral gene transfer
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Parkinson's disease is characterized by a progressive degeneration of dopaminergic neurons in the substantia nigra, leading to a loss of dopamine in the target structure striatum and development of motor symptoms, such as bradykinesia, rigidity and tremor. New experimental treatment strategies for Parkinson's disease are aimed at either preventing the degeneration of the dopaminergic neurons, or at restoring dopamine in the striatum by fetal dopaminergic transplants. In this thesis work, we have evaluated the long-term effects of glial cell line-derived neurotrophic factor (GDNF) on intact, injured and transplanted dopaminergic neurons following GDNF gene delivery using a viral vector system based on lentiviruses. The results show that the lentiviral vectors provide an efficient transfer of the GDNF gene into the nigrostriatal dopamine system, resulting in a stable and long-lasting expression of the GDNF protein at high levels. The neuroprotective effects of lentiviral-mediated delivery of GDNF were evaluated in a rat model of Parkinson's disease and demonstrated that continuous overexpression of GDNF in the striatum provided an efficient protection of the nigral dopamine neurons, however, improvements in motor function were not observed. Instead, GDNF induced an aberrant sprouting of nigrostriatal fibers in areas outside of the striatum, and the phenotypic expression of tyrosine hydroxylase was reduced in the preserved dopaminergic terminals. We further evaluated the GDNF-induced downregulation of tyrosine hydroxylase in the intact nigrostriatal dopamine system and showed that this effect was both time- and dose-dependent, and did not seem to have a detrimental effect on normal dopamine neurotransmission. The lentiviral vector was also used to study the long-term effects of GDNF on the survival and function of transplanted fetal dopamine neurons. GDNF initially increased the survival of the grafted dopamine neurons, however, the protected cells failed to survive long-term and the presence of GDNF around the grafts appeared to be detrimental to the transplant-induced recovery in these animals. Based on the observation that long-term and continuous GDNF delivery may have compromising effects on the functional outcome in either a neuroprotective or restorative paradigm, we developed a regulatable lentiviral vector system for controlled expression of GDNF in the rat brain. Efficient induction of GDNF gene expression was obtained following injection of the regulated lentiviral vector into the striatum, however, a significant basal expression was also observed, demonstrating the need to further improve the vector system for tight regulation in vivo. The findings of this thesis will have implications for the development of a GDNF gene therapy approach in Parkinson's disease.
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| 7. |
- Georgievska, Biljana, et al.
(författare)
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Neuroprotection in the rat Parkinson model by intrastriatal GDNF gene transfer using a lentiviral vector.
- 2002
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Ingår i: NeuroReport. - 1473-558X. ; 13:1, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- We used a recombinant lentiviral vector (rLV) for gene delivery of GDNF to the striatum, and assessed its neuroprotective effects in the intrastriatal 6-hydroxydopamine (6-OHDA) lesion model.The level of GDNF expression obtained with the rLV-GDNF vector was dose-related and ranged between 0.9-9.3 ng/mg tissue in the transduced striatum, as determined by ELISA, and 0.2-3.0 ng/mg tissue were detected in the ipsilateral substantia nigra (SN), due to anterograde transport of the GDNF protein. GDNF expression was apparent at 4 days and maintained for > 8 months after injection. Striatal delivery of rLV-GDNF efficiently protected the nigral dopamine (DA) neurons and their projection, against the 6-OHDA lesion (65-77% of intact side). Sprouting of the lesioned axons was observed along the nigrostriatal pathway, precisely corresponding to the areas containing anterogradely transported GDNF.
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| 8. |
- Georgievska, Biljana, et al.
(författare)
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Overexpression of glial cell line-derived neurotrophic factor using a lentiviral vector induces time- and dose-dependent downregulation of tyrosine hydroxylase in the intact nigrostriatal dopamine system.
- 2004
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Ingår i: JNeurosci. - 1529-2401. ; 24:29, s. 6437-6445
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Tidskriftsartikel (refereegranskat)abstract
- The effects of continuous glial cell line-derived neurotrophic factor (GDNF) overexpression in the intact nigrostriatal dopamine (DA) system was studied using recombinant lentiviral (rLV) vector delivery of GDNF to the striatum or substantia nigra (SN) in the rat. Intrastriatal delivery of rLV-GDNF resulted in significant overexpression of GDNF in the striatum (2-4 ng/mg tissue) and anterograde transport of GDNF protein to the SN. Striatal rLV-GDNF delivery initially induced an increase in DA turnover (1-6 weeks), accompanied by significant contralateral turning in response to amphetamine, suggesting an enhancement of the DA system on the injected side. Starting 6 weeks after continuous GDNF delivery, we observed a selective downregulation of tyrosine hydroxylase (TH) protein (approximately 70%) that was maintained until the end of the experiment (24 weeks). A similar effect was observed when rLV-GDNF was injected into the SN. The magnitude of TH downregulation was related to the level of GDNF expression and was most pronounced in animals in which the striatal GDNF level exceeded 0.7 ng/mg tissue. The decreased TH protein levels were associated with similar reductions in the in vitro TH enzyme activity (approximately 70%); however, in vivo L-3,4-dihydroxyphenylalanine production rate and DA tissue levels were maintained at normal levels. The results indicate that downregulation of TH protein reflects a compensatory effect in response to continuous GDNF stimulation of the DA neurons mediated by a combination of overactivity at the DA synapse and a direct GDNF-induced action on TH gene expression. This compensatory mechanism is proposed to maintain long-term DA neuron function within the normal range.
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| 9. |
- Georgievska, Biljana, et al.
(författare)
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Regulated delivery of glial cell line-derived neurotrophic factor into rat striatum, using a tetracycline-dependent lentiviral vector.
- 2004
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Ingår i: Human Gene Therapy. - : Mary Ann Liebert Inc. - 1043-0342 .- 1557-7422. ; 15:10, s. 934-944
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a tetracycline-regulated lentiviral vector system, based on the tetracycline-dependent transactivator rtTA2S-M2, was developed for controlled expression of glial cell line-derived neurotrophic factor (GDNF) in the rat brain. Expression of the marker gene green fluorescent protein (GFP) and GDNF was tightly regulated in a dose-dependent manner in neural cell lines in vitro. Injection of high-titer lentiviral vectors into the rat striatum resulted in a 7-fold induction of GDNF tissue levels (1060 pg/mg tissue), when doxycycline (a tetracycline analog) was added to the drinking water. However, low levels of GDNF (150 pg/mg tissue) were also detected in animals that did not receive doxycycline, indicating a significant background leakage from the vector system in vivo. The level of basal expression was markedly reduced when a 10-fold lower dose of the tetracycline-regulated GDNF vector was injected into the striatum (3–11 pg/mg tissue), and doxycycline- induced GDNF tissue levels obtained in these animals were about 190 pg/mg tissue. Doxycycline-induced expression of GDNF resulted in a significant downregulation of the tyrosine hydroxylase (TH) protein in the intact striatum. Removal of doxycycline from the drinking water rapidly (within 3 days) turned off transgenic GDNF mRNA expression and GDNF protein levels in the tissue were completely reduced by 2 weeks, demonstrating the dynamics of the system in vivo. Accordingly, TH protein expression returned to normal by 2–8 weeks after removal of doxycycline, indicating that GDNF-induced downregulation of TH is a reversible event.
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| 10. |
- Jakobsson, Johan, et al.
(författare)
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Efficient transduction of neurons using Ross River glycoprotein-pseudotyped lentiviral vectors.
- 2006
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Ingår i: Gene Therapy. - : Springer Science and Business Media LLC. - 0969-7128 .- 1476-5462. ; 13:12, s. 966-973
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Tidskriftsartikel (refereegranskat)abstract
- Lentiviral vectors are promising tools for CNS gene transfer since they efficiently transduce the cells of the nervous system in vivo. In this study, we have investigated the transduction efficiency of lentiviral vectors pseudotyped with Ross River virus glycoprotein (RRV-G) (RRV-G-pseudotyped lentiviral vectors (RRV-LV)). The RRV is an alphavirus with an extremely broad host range, including the cells of the central nervous system. Previous studies have shown that lentiviral vectors can be efficiently pseudotyped with this envelope protein and have demonstrated promising features of such vectors, including the possibility to establish stable producer cell lines. After injection of RRV-LV expressing green fluorescent protein into different structures in the rat brain we found efficient transduction of both neurons and glial cells. By using two cell-type-specific promoters, neuron-specific enolase and human glial fibrillary acidic protein, we demonstrated cell-specific transgene expression in the desired cell type. Ross River virus glycoprotein-pseudotyped lentiviral vectors also transduced human neural progenitor cells in vitro, showing that receptors for the RRV-G are present on human neural cells.
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| 11. |
- Jakobsson, Johan, et al.
(författare)
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Lesion-dependent regulation of transgene expression in the rat brain using a human glial fibrillary acidic protein-lentiviral vector.
- 2004
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Ingår i: European Journal of Neuroscience. - 1460-9568. ; 19:3, s. 761-765
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Tidskriftsartikel (refereegranskat)abstract
- The ability to regulate transgene expression will be crucial for development of gene therapy to the brain. The most commonly used systems are based on a transactivator in combination with a drug, e.g. the tetracycline-regulated system. Here we describe a different method of transgene regulation by the use of the human glial fibrillary acidic protein (GFAP) promoter. We constructed a lentiviral vector that directs transgene expression to astrocytes. Using toxin-induced lesions we investigated to what extent transgene expression could be regulated in accordance with the activation of the endogenous GFAP gene. In animals receiving excitotoxic lesions of the striatum we detected an eightfold increase of green fluorescent protein (GFP)-expressing cells. The vast majority of these cells did not divide, suggesting that the transgene was indeed regulated in a similar fashion as the endogenous GFAP gene. This finding will lead to the development of lentiviral vectors with autoregulatory capacities that may be very useful for gene therapy to the brain.
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| 12. |
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| 13. |
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| 14. |
- Kirik, Deniz, et al.
(författare)
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Delayed infusion of GDNF promotes recovery of motor function in the partial lesion model of Parkinson's disease
- 2001
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 13:8, s. 1589-1599
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Tidskriftsartikel (refereegranskat)abstract
- Here we studied the effects of glial cell line-derived neurotrophic factor (GDNF) in a rat model that represents the symptomatic stages of Parkinson's disease. GDNF was infused starting 2 weeks after an intrastriatal 6-hydroxydopamine (6-OHDA) lesion in order to halt the ongoing degeneration of the nigrostriatal dopaminergic neurons. GDNF or vehicle was infused in the striatum or the lateral ventricle via an osmotic minipump over a total 4-week period (2-6 weeks postlesion). Motor function was evaluated by the stepping, paw reaching and drug-induced motor asymmetry tests before the pump infusion was initiated, and was repeated once during (5 weeks postlesion) and twice after the withdrawal of the minipumps (7 and 11 weeks postlesion). We found that within two weeks following the lesion approximately 40% of the nigral TH-positive neurons were lost. In the vehicle infusion groups there was an additional 20% cell loss between 2 and 12 weeks after the lesion. This latter cell loss occurred mainly in the caudal part of the SN whereas the cell loss in the rostral SN was almost complete within the first two weeks. Ventricular GDNF infusion completely blocked the late degenerating neurons in the caudal SN and had long lasting behavioural effects on the stepping test and amphetamine rotation, extending to 6 weeks after withdrawal of the factor. Striatal infusion affected the motor behaviour transiently during the infusion period but the motor performance of these animals returned to baseline upon cessation of the GDNF delivery, and the delayed nigral cell loss was marginally affected. We conclude that intraventricular GDNF can successfully block the already initiated degenerative process in the substantia nigra, and that the effects achieved via the striatal route, when GDNF is given acutely after the lesion, diminish as the fibre terminal degeneration proceeds.
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| 15. |
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| 16. |
- Kirik, Deniz, et al.
(författare)
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Reversal of motor impairments in parkinsonian rats by continuous intrastriatal delivery of L-dopa using rAAV-mediated gene transfer.
- 2002
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 99:7, s. 4708-4713
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Tidskriftsartikel (refereegranskat)abstract
- Intrastriatal delivery of the tyrosine hydroxylase gene by viral vectors is being explored as a tool for local delivery of L-dopa in animals with lesions of the nigrostriatal pathway. The functional effects reported using this approach have been disappointing, probably because the striatal L-dopa levels attained have been too low. In the present study, we have defined a critical threshold level of L-dopa, 1.5 pmol/mg of tissue, that has to be reached to induce any significant functional effects. Using new generation high-titer recombinant adeno-associated virus vectors, we show that levels of striatal L-dopa production exceeding this threshold can be obtained provided that tyrosine hydroxylase is coexpressed with the cofactor synthetic enzyme, GTP-cyclohydrolase-1. After striatal transduction with this combination of vectors, substantial functional improvement in both drug-induced and spontaneous behavior was observed in rats with either complete or partial 6-hydroxydopamine lesions of the nigrostriatal pathway. However, complete reversal of motor deficits occurred only in animals in which part of the striatal dopamine innervation was left intact. Spared nigrostriatal fibers thus may convert L-dopa to dopamine and store and release dopamine in a more physiologically relevant manner in the denervated striatum to mediate better striatal output-dependent motor function. We conclude that intrastriatal L-dopa delivery may be a viable strategy for treatment and control of adverse side effects associated with oral L-dopa therapy such as on-off fluctuations and drug-induced dyskinesias in patients with Parkinson's disease.
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| 17. |
- Pezet, S, et al.
(författare)
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Reversal of neurochemical changes and pain-related behavior in a model of neuropathic pain using modified lentiviral vectors expressing GDNF
- 2006
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Ingår i: Molecular Therapy. - : Elsevier BV. - 1525-0024 .- 1525-0016. ; 13:6, s. 1101-1109
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we evaluated the possible use of lentiviral vectors in the treatment of neuropathic pain. We chose to administer GDNF-expressing vectors because of the known beneficial effect of this trophic factor in alleviation of neuropathic pain in adult rodents. Lentiviral vectors expressing either GDNF or control, green fluorescent protein or beta-galactosidase, were injected unilaterally into the spinal dorsal horn 5 weeks before a spinal nerve ligation was induced (or sham surgery for the controls). We observed that intraspinally administered lentiviral vectors resulted in a large and sustained expression of transgenes in both neurons and glial cells. Injection of GDNF-expressing viral vectors induced a significant reduction of ATF-3 up-regulation and 1134 down-regulation in damaged DRG neurons. In addition, it produced a partial but significant reversal of thermal and mechanical hyperalgesia observed following the spinal nerve ligation. In conclusion, our study suggests that lentiviral vectors are efficient tools to induce a marked and sustained expression of trophic factors in specific areas of the CNS and can, even if with some limitations, be efficient in the treatment of neuropathic pain.
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| 18. |
- Rosenblad, Carl, et al.
(författare)
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Long-term striatal overexpression of GDNF selectively downregulates tyrosine hydroxylase in the intact nigrostriatal dopamine system.
- 2003
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 17:2, s. 260-270
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Tidskriftsartikel (refereegranskat)abstract
- Sustained neurotrophic factor treatment in neurodegenerative disorders such as Parkinson's disease is likely to affect both degenerating and intact neurons. To investigate the effect of long-term glial cell line-derived neurotrophic factor (GDNF) overexpression on intact nigrostriatal dopamine neurons, we injected a recombinant lentiviral vector encoding GDNF, or green fluorescent protein, in the right striatum of young adult rats. Thirteen months after viral injection GDNF levels were 4.5 ng/mg tissue in the striatum and 0.9 ng/mg in the substantia nigra as measured by ELISA, representing a 25-100-fold increase above control vector- or nontransduced tissue. GDNF overexpression significantly reduced tyrosine hydroxylase mRNA levels (by 39-72%) in the substantia nigra and ventral tegmental area neurons, and the optical density of tyrosine hydroxylase-immunoreactive innervation in the striatum was reduced by 25-52% with the most prominent reductions appearing caudally. No significant reduction was seen in striatal vesicular monoamine transporter 2-immunoreactivity or [3H]mazindole binding autoradiography to dopamine uptake sites, two other presynaptic markers in dopamine axon terminals. The striatal D1 and D2 receptor binding as determined by [3H]SCH23390 and [3H]spiperone binding, respectively, was unaltered relative to the intact side in both treatment groups. Preproenkephalin mRNA levels in postsynaptic striatal neurons, which increase upon removal of striatal dopamine, were also unaffected by the GDNF treatment. Taken together our findings indicate that sustained GDNF administration to intact nigrostriatal dopamine neurons selectively reduces tyrosine hydroxylase expression, without altering striatal dopamine transmission to the extent that compensatory changes in several other components related to dopamine storage and signalling occur.
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| 19. |
- Winkler, Christian, et al.
(författare)
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Continuous exposure to glial cell line-derived neurotrophic factor to mature dopaminergic transplants impairs the graft's ability to improve spontaneous motor behavior in parkinsonian rats.
- 2006
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Ingår i: Neuroscience. - : Elsevier BV. - 1873-7544 .- 0306-4522. ; 141:1, s. 521-531
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Tidskriftsartikel (refereegranskat)abstract
- Functional recovery following intrastriatal transplantation of fetal dopaminergic neurons in animal models of Parkinson's disease is, at least in part, dependent on the number of surviving dopaminergic neurons and the degree of graft-derived dopaminergic reinnervation of the host striatum. In the present study, we analyzed whether continuous exposure of glial cell line-derived neurotrophic factor (GDNF) to mature dopaminergic grafts could further boost the functional outcome of widespread intrastriatal dopaminergic grafts. Rats with dopamine-denervating lesions received multiple intrastriatal transplants of fetal dopaminergic cells and graft-induced behavioral effects were analyzed in drug-induced and spontaneous motor behaviors. At three months after grafting, animals received intrastriatal injections of recombinant lentiviral vectors encoding for either human GDNF or the green fluorescent protein. Continuous exposure of GDNF to the grafts did not boost the functional recovery beyond what was observed in the control animals. Rather, in some of the spontaneous motor behaviors, animals in the GDNF-group showed deterioration as compared with control animals, and this negative effect of GDNF was associated with a down-regulation of the tyrosine hydroxylase enzyme. Based on these and our earlier results, we propose that intrastriatal administration of GDNF at the time of or shortly after grafting is highly effective in initially promoting the cell survival and fiber outgrowth from the grafts. However, once the grafts are mature, GDNF's ability to boost dopaminergic neurotransmission follows the same dynamics as for the native nigral dopaminergic neurons, which appears to be dependent on the concentration of GDNF. Since rather low doses of glial cell line-derived neurotrophic factor at nanogram levels appear to saturate these effects, it may be critical to adjust GDNF levels using tightly regulated gene expression systems. (c) 2006 IBRO. Published by Elsevier Ltd. All rights reserved.
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| 20. |
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