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Urate and its transgenic depletion modulate neuronal vulnerability in a cellular model of Parkinson's disease.

Cipriani S, Desjardins CA, Burdett TC, Xu Y, Xu K, Schwarzschild MA - PLoS ONE (2012)

Bottom Line: In this study we investigated the effects of modulating intracellular urate concentration on 1-methyl-4-phenyl-pyridinium (MPP(+))-induced degeneration of dopaminergic neurons in cultures of mouse ventral mesencephalon prepared to contain low (neuron-enriched cultures) or high (neuron-glial cultures) percentage of astrocytes.To assess the effect of reducing cellular urate content on MPP(+)-induced toxicity, mesencephalic neurons were prepared from mice over-expressing urate oxidase (UOx).Dopaminergic neurons expressing UOx were more susceptible to MPP(+) in mesencephalic neuron-enriched cultures and to a greater extent in mesencephalic neuron-astrocyte cultures.

View Article: PubMed Central - PubMed

Affiliation: Neurology Department, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, Massachusetts, United States of America. scipriani@partners.org

ABSTRACT
Urate is a major antioxidant as well as the enzymatic end product of purine metabolism in humans. Higher levels correlate with a reduced risk of developing Parkinson's disease (PD) and with a slower rate of PD progression. In this study we investigated the effects of modulating intracellular urate concentration on 1-methyl-4-phenyl-pyridinium (MPP(+))-induced degeneration of dopaminergic neurons in cultures of mouse ventral mesencephalon prepared to contain low (neuron-enriched cultures) or high (neuron-glial cultures) percentage of astrocytes. Urate, added to the cultures 24 hours before and during treatment with MPP(+), attenuated the loss of dopaminergic neurons in neuron-enriched cultures and fully prevented their loss and atrophy in neuron-astrocyte cultures. Exogenous urate was found to increase intracellular urate content in cortical neuronal cultures. To assess the effect of reducing cellular urate content on MPP(+)-induced toxicity, mesencephalic neurons were prepared from mice over-expressing urate oxidase (UOx). Transgenic UOx expression decreased endogenous urate content both in neurons and astrocytes. Dopaminergic neurons expressing UOx were more susceptible to MPP(+) in mesencephalic neuron-enriched cultures and to a greater extent in mesencephalic neuron-astrocyte cultures. Our findings correlate intracellular urate content in dopaminergic neurons with their toxin resistance in a cellular model of PD and suggest a facilitative role for astrocytes in the neuroprotective effect of urate.

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MPP+ effect on non-Tg, Tg and Tg/Tg neuron-enriched cultures.A) MPP+ effect on TH-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) neuronal cultures. B) MPP+ effect on MAP-2-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) cultures. C) Two-way ANOVA followed by Bonferroni multiple comparison test: **P<0.01, ***P<0.001 vs respective non-Tg value; ###P<0.01 vs respective Tg value.
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pone-0037331-g008: MPP+ effect on non-Tg, Tg and Tg/Tg neuron-enriched cultures.A) MPP+ effect on TH-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) neuronal cultures. B) MPP+ effect on MAP-2-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) cultures. C) Two-way ANOVA followed by Bonferroni multiple comparison test: **P<0.01, ***P<0.001 vs respective non-Tg value; ###P<0.01 vs respective Tg value.

Mentions: To determine whether the enzymatic reduction of intracellular urate exacerbates dopaminergic susceptibility to MPP+, neuron-enriched ventral mesencephalon cultures from non-Tg, Tg and Tg/Tg mice were treated with increasing concentrations of toxin for 24 hours. Two-way ANOVA showed that both genotype (F2,232 = 24.61, P<0.0001) and MPP+ concentration (F2,232 = 312.64, P<0.0001) affected the number of TH-IR neurons, and found significant interaction between these two factors (F2,232 = 13.82, P<0.0001). Dopaminergic viability was reduced in UOx expressing cultures in comparison to non-Tg cultures with a maximum effect at 1 µM MPP+, which further reduced TH-IR neuron number by 10% and 18% in Tg and Tg/Tg cultures compared to non-Tg cultures, respectively (Fig. 8A). The EC50 for MPP+ was 5.2 µM (95%CI: 2.8–9.7 µM) in non-Tg cultures, 3.9 µM (95%CI: 2.4–6.4 µM) in Tg and 2.5 µM (95%CI: 0.9–6.8 µM) in Tg/Tg without statistically significant difference among genotypes (F2,232 = 0.5612, P = 0.57).


Urate and its transgenic depletion modulate neuronal vulnerability in a cellular model of Parkinson's disease.

Cipriani S, Desjardins CA, Burdett TC, Xu Y, Xu K, Schwarzschild MA - PLoS ONE (2012)

MPP+ effect on non-Tg, Tg and Tg/Tg neuron-enriched cultures.A) MPP+ effect on TH-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) neuronal cultures. B) MPP+ effect on MAP-2-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) cultures. C) Two-way ANOVA followed by Bonferroni multiple comparison test: **P<0.01, ***P<0.001 vs respective non-Tg value; ###P<0.01 vs respective Tg value.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3351394&req=5

pone-0037331-g008: MPP+ effect on non-Tg, Tg and Tg/Tg neuron-enriched cultures.A) MPP+ effect on TH-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) neuronal cultures. B) MPP+ effect on MAP-2-IR cell number in non-Tg (n = 18), Tg (n = 35) and Tg/Tg (n = 8) cultures. C) Two-way ANOVA followed by Bonferroni multiple comparison test: **P<0.01, ***P<0.001 vs respective non-Tg value; ###P<0.01 vs respective Tg value.
Mentions: To determine whether the enzymatic reduction of intracellular urate exacerbates dopaminergic susceptibility to MPP+, neuron-enriched ventral mesencephalon cultures from non-Tg, Tg and Tg/Tg mice were treated with increasing concentrations of toxin for 24 hours. Two-way ANOVA showed that both genotype (F2,232 = 24.61, P<0.0001) and MPP+ concentration (F2,232 = 312.64, P<0.0001) affected the number of TH-IR neurons, and found significant interaction between these two factors (F2,232 = 13.82, P<0.0001). Dopaminergic viability was reduced in UOx expressing cultures in comparison to non-Tg cultures with a maximum effect at 1 µM MPP+, which further reduced TH-IR neuron number by 10% and 18% in Tg and Tg/Tg cultures compared to non-Tg cultures, respectively (Fig. 8A). The EC50 for MPP+ was 5.2 µM (95%CI: 2.8–9.7 µM) in non-Tg cultures, 3.9 µM (95%CI: 2.4–6.4 µM) in Tg and 2.5 µM (95%CI: 0.9–6.8 µM) in Tg/Tg without statistically significant difference among genotypes (F2,232 = 0.5612, P = 0.57).

Bottom Line: In this study we investigated the effects of modulating intracellular urate concentration on 1-methyl-4-phenyl-pyridinium (MPP(+))-induced degeneration of dopaminergic neurons in cultures of mouse ventral mesencephalon prepared to contain low (neuron-enriched cultures) or high (neuron-glial cultures) percentage of astrocytes.To assess the effect of reducing cellular urate content on MPP(+)-induced toxicity, mesencephalic neurons were prepared from mice over-expressing urate oxidase (UOx).Dopaminergic neurons expressing UOx were more susceptible to MPP(+) in mesencephalic neuron-enriched cultures and to a greater extent in mesencephalic neuron-astrocyte cultures.

View Article: PubMed Central - PubMed

Affiliation: Neurology Department, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, Massachusetts, United States of America. scipriani@partners.org

ABSTRACT
Urate is a major antioxidant as well as the enzymatic end product of purine metabolism in humans. Higher levels correlate with a reduced risk of developing Parkinson's disease (PD) and with a slower rate of PD progression. In this study we investigated the effects of modulating intracellular urate concentration on 1-methyl-4-phenyl-pyridinium (MPP(+))-induced degeneration of dopaminergic neurons in cultures of mouse ventral mesencephalon prepared to contain low (neuron-enriched cultures) or high (neuron-glial cultures) percentage of astrocytes. Urate, added to the cultures 24 hours before and during treatment with MPP(+), attenuated the loss of dopaminergic neurons in neuron-enriched cultures and fully prevented their loss and atrophy in neuron-astrocyte cultures. Exogenous urate was found to increase intracellular urate content in cortical neuronal cultures. To assess the effect of reducing cellular urate content on MPP(+)-induced toxicity, mesencephalic neurons were prepared from mice over-expressing urate oxidase (UOx). Transgenic UOx expression decreased endogenous urate content both in neurons and astrocytes. Dopaminergic neurons expressing UOx were more susceptible to MPP(+) in mesencephalic neuron-enriched cultures and to a greater extent in mesencephalic neuron-astrocyte cultures. Our findings correlate intracellular urate content in dopaminergic neurons with their toxin resistance in a cellular model of PD and suggest a facilitative role for astrocytes in the neuroprotective effect of urate.

Show MeSH
Related in: MedlinePlus