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Parkinson disease (PD) involves a selective degeneration of nigrostriatal dopaminergic (DA) neurons. This pathology can be modeled in experimental animals by the administration of MPTP (1-metyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine), a toxin which selectively destroys DA neurons and causes anatomical, behavioral, and biochemical changes similar to those seen in Parkinson's disease. In vivo MPTP is converted to MPP+ (1-methyl-4-phenylpyridinium) and this is the active neurotoxic agent that selectively destroys DA neurons. In dopaminergic neuron cultures MPP+ has similar effects and it is therefore possible to model the PD pathology in vitro.
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A primary culture of mesencephalic neurons, which contains DA neurons, are exposed to MPP+ under controlled condition (medium without serum, concentration and duration of intoxication, ...). The number of survival neurons is evaluated by a manual counting after an immuno-staining of tyrosine hydroxylase to identify DA neurons.
To evaluate the neuroprotective properties of a new compound, two types of study can be conducted in this model:
1) Protective: The test compound is added to the medium 24 h before the induction of MPP+ damage.
2) Reversal: The test compound is added to the medium 24 h after MPP+ intoxication to evaluate its potential to reverse injury.
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Picture of primary culture of mesencephalic neurons
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Pictures show primary culture of mesencephalic neurons. In upper panel it is phase contrast photograph and in the bottom fluorescent microscopy: nucleus are stained in blue and dopaminergic neurons in red.
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Effect of several reference compounds on MPP+ - induced death using the protective protocol
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Effects of reference compounds to counteract MPP+ injury: GDNF and BDNF as a combination of neurotrophic compounds, Riluzol to impair glutamatergic transmission, cAMP to activate cyclic-AMP-dependent protein kinase, zVAD (Z-Val-Ala-Asp-FMZ) as a cell permeable inhibitor for caspase 1 and 3.
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Effect of GDNF and BDNF in combination on DA neurones injured by MPP+
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Protective and reversal effect of BDNF and GDNF on damage induced by MPP+ on DA neurons.
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Gilles G., Hung S.T. Reichmann H. and Rausch W.D. Oxidative stress to dopaminergic neurons as models of Parkinson's disease. Ann. N. Y. Acad. Sci. (2004) 1018: 533-540.
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Eberhardt O. and Schulz J. B. Apoptotic mechanisms and antiapoptotic therapy in the MPTP model of Parkinson's disease. Tox. Letters (2003) 139:135-151.
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Dauer W. and Pezedborski S. Parkinson's disease: mechanism and models. Neuron (2003) 39:889-909.
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Kaul S., Kanthasamy A., Kitazawa M., Anantharam V. and Kanthasamy A.G. Caspase-3 dependent proteolytic activation of protein kinase C delta mediates and regulates 1-methy-4-phenylpyridinium (MPP+)-induced apoptotic cell death in dopaminergic cells: relevance to oxidative stress in dopaminergic degeneration. Eur. J. Neurosci. (2003) 18:1387-1401.
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