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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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Related in: MedlinePlus

Inhibition of catalase activity attenuates pioglitazone-induced protection from H2O2 in cortical neuronal cultures. (a) The effect of hydrogen peroxide exposure (MIN H2O2; 250 μM) on cortical neuronal viability in vitro compared to serum free minimal media (MIN) (**P < 0.01 as compared with MIN); the effect of pioglitazone (1 μM) and the specific catalase inhibitor, 3-aminotriazole (3-AT) (10 mM) (**P < 0.01 MIN H2O2 compared to MIN H2O2 Pio 1 μM; and **P < 0.01 MIN H2O2 Pio 1 μM compared to MIN H2O2 Pio 1 μM 3-AT 10 mM) and the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) on cortical neuronal viability. Cultures were treated with pioglitazone for 1 hour prior to incubation with 3-AT for 1 hour followed by exposure to hydrogen peroxide. Cultures were treated with catalase for 1 hour prior to exposure to hydrogen peroxide. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in MIN medium. Statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of hydrogen peroxide exposure (250 μM H2O2) on cortical neuronal cell survival (number of βIII-tubulin cells per field; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on cortical neuronal viability exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT (10 mM) on pioglitazone-induced neuroprotection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). (c) Effect of hydrogen peroxide exposure (250 μM H2O2) on axon length within neuronal cultures (determined by SMI312 staining; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on axon length in neurons exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT, (10 mM) on pioglitazone-induced axon protection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). Values represent the mean ± SEM from at least three separate experiments. ANOVA, analysis of variance; MTT, 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide; SEM, standard error of the mean.
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Figure 5: Inhibition of catalase activity attenuates pioglitazone-induced protection from H2O2 in cortical neuronal cultures. (a) The effect of hydrogen peroxide exposure (MIN H2O2; 250 μM) on cortical neuronal viability in vitro compared to serum free minimal media (MIN) (**P < 0.01 as compared with MIN); the effect of pioglitazone (1 μM) and the specific catalase inhibitor, 3-aminotriazole (3-AT) (10 mM) (**P < 0.01 MIN H2O2 compared to MIN H2O2 Pio 1 μM; and **P < 0.01 MIN H2O2 Pio 1 μM compared to MIN H2O2 Pio 1 μM 3-AT 10 mM) and the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) on cortical neuronal viability. Cultures were treated with pioglitazone for 1 hour prior to incubation with 3-AT for 1 hour followed by exposure to hydrogen peroxide. Cultures were treated with catalase for 1 hour prior to exposure to hydrogen peroxide. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in MIN medium. Statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of hydrogen peroxide exposure (250 μM H2O2) on cortical neuronal cell survival (number of βIII-tubulin cells per field; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on cortical neuronal viability exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT (10 mM) on pioglitazone-induced neuroprotection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). (c) Effect of hydrogen peroxide exposure (250 μM H2O2) on axon length within neuronal cultures (determined by SMI312 staining; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on axon length in neurons exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT, (10 mM) on pioglitazone-induced axon protection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). Values represent the mean ± SEM from at least three separate experiments. ANOVA, analysis of variance; MTT, 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide; SEM, standard error of the mean.


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)

Inhibition of catalase activity attenuates pioglitazone-induced protection from H2O2 in cortical neuronal cultures. (a) The effect of hydrogen peroxide exposure (MIN H2O2; 250 μM) on cortical neuronal viability in vitro compared to serum free minimal media (MIN) (**P < 0.01 as compared with MIN); the effect of pioglitazone (1 μM) and the specific catalase inhibitor, 3-aminotriazole (3-AT) (10 mM) (**P < 0.01 MIN H2O2 compared to MIN H2O2 Pio 1 μM; and **P < 0.01 MIN H2O2 Pio 1 μM compared to MIN H2O2 Pio 1 μM 3-AT 10 mM) and the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) on cortical neuronal viability. Cultures were treated with pioglitazone for 1 hour prior to incubation with 3-AT for 1 hour followed by exposure to hydrogen peroxide. Cultures were treated with catalase for 1 hour prior to exposure to hydrogen peroxide. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in MIN medium. Statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of hydrogen peroxide exposure (250 μM H2O2) on cortical neuronal cell survival (number of βIII-tubulin cells per field; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on cortical neuronal viability exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT (10 mM) on pioglitazone-induced neuroprotection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). (c) Effect of hydrogen peroxide exposure (250 μM H2O2) on axon length within neuronal cultures (determined by SMI312 staining; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on axon length in neurons exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT, (10 mM) on pioglitazone-induced axon protection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). Values represent the mean ± SEM from at least three separate experiments. ANOVA, analysis of variance; MTT, 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide; SEM, standard error of the mean.
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Figure 5: Inhibition of catalase activity attenuates pioglitazone-induced protection from H2O2 in cortical neuronal cultures. (a) The effect of hydrogen peroxide exposure (MIN H2O2; 250 μM) on cortical neuronal viability in vitro compared to serum free minimal media (MIN) (**P < 0.01 as compared with MIN); the effect of pioglitazone (1 μM) and the specific catalase inhibitor, 3-aminotriazole (3-AT) (10 mM) (**P < 0.01 MIN H2O2 compared to MIN H2O2 Pio 1 μM; and **P < 0.01 MIN H2O2 Pio 1 μM compared to MIN H2O2 Pio 1 μM 3-AT 10 mM) and the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) on cortical neuronal viability. Cultures were treated with pioglitazone for 1 hour prior to incubation with 3-AT for 1 hour followed by exposure to hydrogen peroxide. Cultures were treated with catalase for 1 hour prior to exposure to hydrogen peroxide. Cell viability was assessed by MTT assay. Data are expressed as percentage of cells grown in MIN medium. Statistical significance was obtained by one-way ANOVA followed by Bonferroni post-hoc test. (b) Effect of hydrogen peroxide exposure (250 μM H2O2) on cortical neuronal cell survival (number of βIII-tubulin cells per field; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on cortical neuronal viability exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT (10 mM) on pioglitazone-induced neuroprotection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). (c) Effect of hydrogen peroxide exposure (250 μM H2O2) on axon length within neuronal cultures (determined by SMI312 staining; **P < 0.01 as compared with MIN, Student's t-test); the effect of pioglitazone (1 μM) on axon length in neurons exposed to H2O2 (*P < 0.05 compared with MIN H2O2); the effect of catalase exposure (MIN H2O2 CAT; 100 U/ml) (**P < 0.01 MIN H2O2 compared to MIN H2O2 CAT) and the effect of the specific catalase inhibitor, 3-AT, (10 mM) on pioglitazone-induced axon protection from H2O2 (**P < 0.01 comparing MIN H2O2 Pio 1 μM with MIN H2O2 Pio 1 μM 3-AT 10 mM). Values represent the mean ± SEM from at least three separate experiments. ANOVA, analysis of variance; MTT, 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide; SEM, standard error of the mean.
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