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The PPAR-γ agonist pioglitazone protects cortical neurons from inflammatory mediators via improvement in peroxisomal function.

Gray E, Ginty M, Kemp K, Scolding N, Wilkins A - J Neuroinflammation (2012)

Bottom Line: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase.In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Multiple Sclerosis and Stem Cell Group, Burden Centre, Institute of Clinical Neurosciences, Frenchay Hospital, University of Bristol, Bristol BS16 1JB, UK. elizabeth.gray@bristol.ac.uk

ABSTRACT

Background: Inflammation is known to play a pivotal role in mediating neuronal damage and axonal injury in a variety of neurodegenerative disorders. Among the range of inflammatory mediators, nitric oxide and hydrogen peroxide are potent neurotoxic agents. Recent evidence has suggested that oligodendrocyte peroxisomes may play an important role in protecting neurons from inflammatory damage.

Methods: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.

Results: Pioglitazone protected neurons and axons against both nitric-oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase. In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

Conclusions: Collectively, these observations provide evidence that modulation of PPAR-gamma activity and peroxisomal function by pioglitazone attenuates both NO and hydrogen peroxide-mediated neuronal and axonal damage suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

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Effect of pioglitazone on DETANONOate-mediated reductions in neuronal survival in cortical neuronal cultures. (a) The effect of DETANONOate exposure (MIN NO) on cortical neuronal cell viability in vitro compared to serum free minimal media (MIN); and the effect of different concentrations (10 nM to 10 μM) of peroxisome proliferator activated receptor-γ (PPAR-γ) agonist, pioglitazone (Pio) on cortical neuronal cell viability in vitro (***P < 0.001 compared to MIN and *P < 0.05 compared to MIN NO; n = 5). Cultures were pre-treated with pioglitazone for 1 hour, prior to exposure to DETANONOate. (b) The effect of pre-treatment with the specific PPAR-γ antagonist, GW9662 (1 μM) on cortical neuronal viability in vitro compared to the effect of pioglitazone (1 μM) (***P < 0.001 compared to MIN, *P < 0.05 compared to MIN NO and *P < 0.05 compared to MIN NO Pio 1 μM). Cultures were treated with GW9662 for 1 hour prior to incubation with pioglitazone and DETANONOate. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in B27. Statistical significance was obtained by one-way ANOVA followed by a Bonferroni post-hoc test. ANOVA, analysis of variance.
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Figure 1: Effect of pioglitazone on DETANONOate-mediated reductions in neuronal survival in cortical neuronal cultures. (a) The effect of DETANONOate exposure (MIN NO) on cortical neuronal cell viability in vitro compared to serum free minimal media (MIN); and the effect of different concentrations (10 nM to 10 μM) of peroxisome proliferator activated receptor-γ (PPAR-γ) agonist, pioglitazone (Pio) on cortical neuronal cell viability in vitro (***P < 0.001 compared to MIN and *P < 0.05 compared to MIN NO; n = 5). Cultures were pre-treated with pioglitazone for 1 hour, prior to exposure to DETANONOate. (b) The effect of pre-treatment with the specific PPAR-γ antagonist, GW9662 (1 μM) on cortical neuronal viability in vitro compared to the effect of pioglitazone (1 μM) (***P < 0.001 compared to MIN, *P < 0.05 compared to MIN NO and *P < 0.05 compared to MIN NO Pio 1 μM). Cultures were treated with GW9662 for 1 hour prior to incubation with pioglitazone and DETANONOate. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in B27. Statistical significance was obtained by one-way ANOVA followed by a Bonferroni post-hoc test. ANOVA, analysis of variance.

Mentions: To determine whether the PPAR-γ agonist pioglitazone could protect against the deleterious effects of a NO donor, cortical neuronal cultures were incubated for 1 hour in the presence of increasing concentrations (10 nM to 100 μM) of pioglitazone prior to exposure to DETANONOate (0.1 mM) for 24 hours. Cell viability was evaluated by assessing the reduction of the tetrazolium salt MTT, providing a general index of the metabolic state. Neuronal viability was significantly reduced when compared to control after nitric oxide exposure (Figure 1a). Preliminary dose response experiments determined the range of concentrations which appeared to have beneficial effects. In the presence of a range of concentrations (10 μM, 1 μM and 0.1 μM) of pioglitazone, neuronal viability was significantly increased during exposure to nitric oxide (Figure 1a). To examine whether the neuroprotection afforded by pioglitazone was a receptor-dependent effect, neurons were exposed to the specific PPAR-γ antagonist GW9662 (1 μM) for 1 hour, prior to incubation with pioglitazone (1 μM). As expected, neuronal viability was significantly increased following exposure to pioglitazone and this effect was abrogated in the presence of GW9662 (Figure 1b). Neuronal viability was not significantly different following exposure to the antagonist alone (Figure 1b). On the basis of these results, the concentrations of pioglitazone used to further study the effects of PPAR-γ activation on neuronal survival were determined. The final concentration of DMSO (vehicle) was always less than 0.1% and had no effects on cell viability (data not shown).


The PPAR-γ agonist pioglitazone protects cortical neurons from inflammatory mediators via improvement in peroxisomal function.

Gray E, Ginty M, Kemp K, Scolding N, Wilkins A - J Neuroinflammation (2012)

Effect of pioglitazone on DETANONOate-mediated reductions in neuronal survival in cortical neuronal cultures. (a) The effect of DETANONOate exposure (MIN NO) on cortical neuronal cell viability in vitro compared to serum free minimal media (MIN); and the effect of different concentrations (10 nM to 10 μM) of peroxisome proliferator activated receptor-γ (PPAR-γ) agonist, pioglitazone (Pio) on cortical neuronal cell viability in vitro (***P < 0.001 compared to MIN and *P < 0.05 compared to MIN NO; n = 5). Cultures were pre-treated with pioglitazone for 1 hour, prior to exposure to DETANONOate. (b) The effect of pre-treatment with the specific PPAR-γ antagonist, GW9662 (1 μM) on cortical neuronal viability in vitro compared to the effect of pioglitazone (1 μM) (***P < 0.001 compared to MIN, *P < 0.05 compared to MIN NO and *P < 0.05 compared to MIN NO Pio 1 μM). Cultures were treated with GW9662 for 1 hour prior to incubation with pioglitazone and DETANONOate. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in B27. Statistical significance was obtained by one-way ANOVA followed by a Bonferroni post-hoc test. ANOVA, analysis of variance.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368767&req=5

Figure 1: Effect of pioglitazone on DETANONOate-mediated reductions in neuronal survival in cortical neuronal cultures. (a) The effect of DETANONOate exposure (MIN NO) on cortical neuronal cell viability in vitro compared to serum free minimal media (MIN); and the effect of different concentrations (10 nM to 10 μM) of peroxisome proliferator activated receptor-γ (PPAR-γ) agonist, pioglitazone (Pio) on cortical neuronal cell viability in vitro (***P < 0.001 compared to MIN and *P < 0.05 compared to MIN NO; n = 5). Cultures were pre-treated with pioglitazone for 1 hour, prior to exposure to DETANONOate. (b) The effect of pre-treatment with the specific PPAR-γ antagonist, GW9662 (1 μM) on cortical neuronal viability in vitro compared to the effect of pioglitazone (1 μM) (***P < 0.001 compared to MIN, *P < 0.05 compared to MIN NO and *P < 0.05 compared to MIN NO Pio 1 μM). Cultures were treated with GW9662 for 1 hour prior to incubation with pioglitazone and DETANONOate. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in B27. Statistical significance was obtained by one-way ANOVA followed by a Bonferroni post-hoc test. ANOVA, analysis of variance.
Mentions: To determine whether the PPAR-γ agonist pioglitazone could protect against the deleterious effects of a NO donor, cortical neuronal cultures were incubated for 1 hour in the presence of increasing concentrations (10 nM to 100 μM) of pioglitazone prior to exposure to DETANONOate (0.1 mM) for 24 hours. Cell viability was evaluated by assessing the reduction of the tetrazolium salt MTT, providing a general index of the metabolic state. Neuronal viability was significantly reduced when compared to control after nitric oxide exposure (Figure 1a). Preliminary dose response experiments determined the range of concentrations which appeared to have beneficial effects. In the presence of a range of concentrations (10 μM, 1 μM and 0.1 μM) of pioglitazone, neuronal viability was significantly increased during exposure to nitric oxide (Figure 1a). To examine whether the neuroprotection afforded by pioglitazone was a receptor-dependent effect, neurons were exposed to the specific PPAR-γ antagonist GW9662 (1 μM) for 1 hour, prior to incubation with pioglitazone (1 μM). As expected, neuronal viability was significantly increased following exposure to pioglitazone and this effect was abrogated in the presence of GW9662 (Figure 1b). Neuronal viability was not significantly different following exposure to the antagonist alone (Figure 1b). On the basis of these results, the concentrations of pioglitazone used to further study the effects of PPAR-γ activation on neuronal survival were determined. The final concentration of DMSO (vehicle) was always less than 0.1% and had no effects on cell viability (data not shown).

Bottom Line: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase.In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

View Article: PubMed Central - HTML - PubMed

Affiliation: Multiple Sclerosis and Stem Cell Group, Burden Centre, Institute of Clinical Neurosciences, Frenchay Hospital, University of Bristol, Bristol BS16 1JB, UK. elizabeth.gray@bristol.ac.uk

ABSTRACT

Background: Inflammation is known to play a pivotal role in mediating neuronal damage and axonal injury in a variety of neurodegenerative disorders. Among the range of inflammatory mediators, nitric oxide and hydrogen peroxide are potent neurotoxic agents. Recent evidence has suggested that oligodendrocyte peroxisomes may play an important role in protecting neurons from inflammatory damage.

Methods: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia.

Results: Pioglitazone protected neurons and axons against both nitric-oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase. In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase.

Conclusions: Collectively, these observations provide evidence that modulation of PPAR-gamma activity and peroxisomal function by pioglitazone attenuates both NO and hydrogen peroxide-mediated neuronal and axonal damage suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

Show MeSH
Related in: MedlinePlus