γ-tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury

Sue Mian Then, Coral Sanfeliu, Gapor M. Top, Wan Zurinah Wan Ngah, Musalmah Mazlan

    Research output: Contribution to journalArticle

    5 Citations (Scopus)

    Abstract

    Background: Down syndrome (DS) neurons are more susceptible to oxidative stress and previous studies have shown that vitamin E was able to reduce oxidative stress and improve DS neurons' viability. Therefore, this study was done to investigate the protective role of γ-tocotrienol (γT3) in DS neurons from hydrogen peroxide (H 2O 2)-induced oxidative stress. The pro-apoptosis tendency of γT3 was compared to α-tocopherol (αT) in non-stress condition as well. Methods. Primary culture of DS and euploid neurons were divided into six groups of treatment: control, H 2O 2, γT3 pre-treatment with H 2O 2, γT3 only, αT pre-treatment with H 2O 2and αT only. The treatments were assessed by MTS assay and apoptosis assay by single-stranded DNA (ssDNA) apoptosis ELISA assay, Hoechst and Neu-N immunofluorescence staining. The cellular uptake of γT3 and αT was determined by HPLC while protein expressions were determined by Western blot. Comparison between groups was made by the Student's t test, one-way ANOVA and Bonferroni adjustment as well as two-way ANOVA for multiple comparisons. Results: One day incubation of γT3 was able to reduced apoptosis of DS neurons by 10%, however γT3 was cytotoxic at longer incubation period (14 days) and at concentrations 100 M. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H 2O 2-treated DS and euploid neurons by 10% in which the effects were minimal to maintain most of the DS cells' morphology. γT3 act as a free radical scavenger by reducing ROS generated by H 2O 2. In untreated controls, DS neurons showed lower Bcl-2/Bax ratio and p53 expression compared to normal neurons, while cPKC and PKC-δ expressions were higher in DS neurons. On the other hand, pre-treatment of γT3 in H 2O 2-treated DS neurons have reduced Bcl-2/Bax ratio, which was not shown in euploid neurons. This suggests that pre-treatment of γT3 did not promote DS cell survival. Meanwhile γT3 and αT treatments without H 2O 2as well as pre-treatment of γT3 and αT induced changes in cPKC and PKC-δ expression in DS neurons suggesting interaction of γT3 and αT with PKC activity. Conclusion: Our study suggests that γT3 pre-treatment are not sufficient to protect DS neurons from H 2O 2-induced oxidative assault, instead induced the apoptosis process.

    Original languageEnglish
    Article number1
    JournalNutrition and Metabolism
    Volume9
    DOIs
    Publication statusPublished - 2012

    Fingerprint

    Tocotrienols
    Down Syndrome
    Hydrogen Peroxide
    Neurons
    Wounds and Injuries
    Apoptosis
    Therapeutics
    Oxidative Stress
    Cell Survival
    Analysis of Variance
    Free Radical Scavengers
    Tocopherols
    Single-Stranded DNA
    Vitamin E

    Keywords

    • γ-tocotrienol
    • Apoptosis
    • Down syndrome
    • human neurons
    • oxidative stress
    • vitamin E

    ASJC Scopus subject areas

    • Medicine (miscellaneous)
    • Nutrition and Dietetics
    • Endocrinology, Diabetes and Metabolism

    Cite this

    γ-tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury. / Then, Sue Mian; Sanfeliu, Coral; Top, Gapor M.; Wan Ngah, Wan Zurinah; Mazlan, Musalmah.

    In: Nutrition and Metabolism, Vol. 9, 1, 2012.

    Research output: Contribution to journalArticle

    Then, Sue Mian ; Sanfeliu, Coral ; Top, Gapor M. ; Wan Ngah, Wan Zurinah ; Mazlan, Musalmah. / γ-tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury. In: Nutrition and Metabolism. 2012 ; Vol. 9.
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    title = "γ-tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury",
    abstract = "Background: Down syndrome (DS) neurons are more susceptible to oxidative stress and previous studies have shown that vitamin E was able to reduce oxidative stress and improve DS neurons' viability. Therefore, this study was done to investigate the protective role of γ-tocotrienol (γT3) in DS neurons from hydrogen peroxide (H 2O 2)-induced oxidative stress. The pro-apoptosis tendency of γT3 was compared to α-tocopherol (αT) in non-stress condition as well. Methods. Primary culture of DS and euploid neurons were divided into six groups of treatment: control, H 2O 2, γT3 pre-treatment with H 2O 2, γT3 only, αT pre-treatment with H 2O 2and αT only. The treatments were assessed by MTS assay and apoptosis assay by single-stranded DNA (ssDNA) apoptosis ELISA assay, Hoechst and Neu-N immunofluorescence staining. The cellular uptake of γT3 and αT was determined by HPLC while protein expressions were determined by Western blot. Comparison between groups was made by the Student's t test, one-way ANOVA and Bonferroni adjustment as well as two-way ANOVA for multiple comparisons. Results: One day incubation of γT3 was able to reduced apoptosis of DS neurons by 10{\%}, however γT3 was cytotoxic at longer incubation period (14 days) and at concentrations 100 M. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H 2O 2-treated DS and euploid neurons by 10{\%} in which the effects were minimal to maintain most of the DS cells' morphology. γT3 act as a free radical scavenger by reducing ROS generated by H 2O 2. In untreated controls, DS neurons showed lower Bcl-2/Bax ratio and p53 expression compared to normal neurons, while cPKC and PKC-δ expressions were higher in DS neurons. On the other hand, pre-treatment of γT3 in H 2O 2-treated DS neurons have reduced Bcl-2/Bax ratio, which was not shown in euploid neurons. This suggests that pre-treatment of γT3 did not promote DS cell survival. Meanwhile γT3 and αT treatments without H 2O 2as well as pre-treatment of γT3 and αT induced changes in cPKC and PKC-δ expression in DS neurons suggesting interaction of γT3 and αT with PKC activity. Conclusion: Our study suggests that γT3 pre-treatment are not sufficient to protect DS neurons from H 2O 2-induced oxidative assault, instead induced the apoptosis process.",
    keywords = "γ-tocotrienol, Apoptosis, Down syndrome, human neurons, oxidative stress, vitamin E",
    author = "Then, {Sue Mian} and Coral Sanfeliu and Top, {Gapor M.} and {Wan Ngah}, {Wan Zurinah} and Musalmah Mazlan",
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    T1 - γ-tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury

    AU - Then, Sue Mian

    AU - Sanfeliu, Coral

    AU - Top, Gapor M.

    AU - Wan Ngah, Wan Zurinah

    AU - Mazlan, Musalmah

    PY - 2012

    Y1 - 2012

    N2 - Background: Down syndrome (DS) neurons are more susceptible to oxidative stress and previous studies have shown that vitamin E was able to reduce oxidative stress and improve DS neurons' viability. Therefore, this study was done to investigate the protective role of γ-tocotrienol (γT3) in DS neurons from hydrogen peroxide (H 2O 2)-induced oxidative stress. The pro-apoptosis tendency of γT3 was compared to α-tocopherol (αT) in non-stress condition as well. Methods. Primary culture of DS and euploid neurons were divided into six groups of treatment: control, H 2O 2, γT3 pre-treatment with H 2O 2, γT3 only, αT pre-treatment with H 2O 2and αT only. The treatments were assessed by MTS assay and apoptosis assay by single-stranded DNA (ssDNA) apoptosis ELISA assay, Hoechst and Neu-N immunofluorescence staining. The cellular uptake of γT3 and αT was determined by HPLC while protein expressions were determined by Western blot. Comparison between groups was made by the Student's t test, one-way ANOVA and Bonferroni adjustment as well as two-way ANOVA for multiple comparisons. Results: One day incubation of γT3 was able to reduced apoptosis of DS neurons by 10%, however γT3 was cytotoxic at longer incubation period (14 days) and at concentrations 100 M. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H 2O 2-treated DS and euploid neurons by 10% in which the effects were minimal to maintain most of the DS cells' morphology. γT3 act as a free radical scavenger by reducing ROS generated by H 2O 2. In untreated controls, DS neurons showed lower Bcl-2/Bax ratio and p53 expression compared to normal neurons, while cPKC and PKC-δ expressions were higher in DS neurons. On the other hand, pre-treatment of γT3 in H 2O 2-treated DS neurons have reduced Bcl-2/Bax ratio, which was not shown in euploid neurons. This suggests that pre-treatment of γT3 did not promote DS cell survival. Meanwhile γT3 and αT treatments without H 2O 2as well as pre-treatment of γT3 and αT induced changes in cPKC and PKC-δ expression in DS neurons suggesting interaction of γT3 and αT with PKC activity. Conclusion: Our study suggests that γT3 pre-treatment are not sufficient to protect DS neurons from H 2O 2-induced oxidative assault, instead induced the apoptosis process.

    AB - Background: Down syndrome (DS) neurons are more susceptible to oxidative stress and previous studies have shown that vitamin E was able to reduce oxidative stress and improve DS neurons' viability. Therefore, this study was done to investigate the protective role of γ-tocotrienol (γT3) in DS neurons from hydrogen peroxide (H 2O 2)-induced oxidative stress. The pro-apoptosis tendency of γT3 was compared to α-tocopherol (αT) in non-stress condition as well. Methods. Primary culture of DS and euploid neurons were divided into six groups of treatment: control, H 2O 2, γT3 pre-treatment with H 2O 2, γT3 only, αT pre-treatment with H 2O 2and αT only. The treatments were assessed by MTS assay and apoptosis assay by single-stranded DNA (ssDNA) apoptosis ELISA assay, Hoechst and Neu-N immunofluorescence staining. The cellular uptake of γT3 and αT was determined by HPLC while protein expressions were determined by Western blot. Comparison between groups was made by the Student's t test, one-way ANOVA and Bonferroni adjustment as well as two-way ANOVA for multiple comparisons. Results: One day incubation of γT3 was able to reduced apoptosis of DS neurons by 10%, however γT3 was cytotoxic at longer incubation period (14 days) and at concentrations 100 M. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H 2O 2-treated DS and euploid neurons by 10% in which the effects were minimal to maintain most of the DS cells' morphology. γT3 act as a free radical scavenger by reducing ROS generated by H 2O 2. In untreated controls, DS neurons showed lower Bcl-2/Bax ratio and p53 expression compared to normal neurons, while cPKC and PKC-δ expressions were higher in DS neurons. On the other hand, pre-treatment of γT3 in H 2O 2-treated DS neurons have reduced Bcl-2/Bax ratio, which was not shown in euploid neurons. This suggests that pre-treatment of γT3 did not promote DS cell survival. Meanwhile γT3 and αT treatments without H 2O 2as well as pre-treatment of γT3 and αT induced changes in cPKC and PKC-δ expression in DS neurons suggesting interaction of γT3 and αT with PKC activity. Conclusion: Our study suggests that γT3 pre-treatment are not sufficient to protect DS neurons from H 2O 2-induced oxidative assault, instead induced the apoptosis process.

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    KW - Apoptosis

    KW - Down syndrome

    KW - human neurons

    KW - oxidative stress

    KW - vitamin E

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