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

Nutrition & Metabolism

Musalmah Mazlan³  Wan Zurinah Wan Ngah³  Gapor M Top¹  Coral Sanfeliu⁴  Sue-Mian Then² 

[1] Malaysian Palm Oil Board, Bangi, Selangor, Malaysia;UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia (UKM), Kuala Lumpur, Malaysia;Department of Biochemistry, Faculty of Medicine, Universiti Kebangsaan Malaysia (UKM), Kuala Lumpur, Malaysia;Institut d'Investigacions Biomèdiques de Barcelona (IIBB), CSIC-IDIBAPS, Barcelona, Spain

关键词: vitamin E;    γ-tocotrienol;    oxidative stress;    human neurons;    Down syndrome;    Apoptosis;   

Others  :  1131810
DOI  :  10.1186/1743-7075-9-1

 received in 2011-11-02, accepted in 2012-01-05,  发布年份 2012

【 摘 要 】

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 (H₂O₂) -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, H₂O₂, γT3 pre-treatment with H₂O₂, γT3 only, αT pre-treatment with H₂O₂ and 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 μM. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H₂O₂-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 H₂O₂. 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 H₂O₂-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 H₂O₂ as 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 H₂O₂-induced oxidative assault, instead induced the apoptosis process.

【 授权许可】

   
2012 Then et al; licensee BioMed Central Ltd.

【 图 表 】

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