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α-Tocopherol at nanomolar concentration protects PC12 cells from hydrogen peroxide-induced death and modulates protein kinase activities.

Zakharova IO, Sokolova TV, Bayunova LV, Vlasova YA, Rychkova MP, Avrova NF - Int J Mol Sci (2012)

Bottom Line: For the first time, the protective effect of α-tocopherol was shown to depend on its concentration in the nanomolar range (1 nM < 10 nM < 100 nM), if the pre-incubation time was 18 h.Nanomolar and micromolar α-tocopherol decreased the number of PC12 cells in late apoptosis induced by H(2)O(2) to the same extent if pre-incubation time was 18 h.The data obtained suggest that inhibition by α-tocopherol in late stage ERK 1/2 and Akt activation induced by H(2)O(2) in PC12 cells makes contribution to its protective effect, while total inhibition of these enzymes is not protective.

View Article: PubMed Central - PubMed

Affiliation: Department of Comparative Neurochemistry, Institute of Evolutionary Physiology and Biochemistry of Russian Academy of Sciences, Thorez avenue, 44, Saint-Petersburg 194223, Russia; E-Mails: zakhar@iephb.ru (I.O.Z.); sokolt1956@mail.ru (T.V.S.); bayunoval@mail.ru (L.V.B.); yousia@mail.ru (Y.A.V.); involved@mail.ru (M.P.R.).

ABSTRACT
The aim of this work was to compare protective and anti-apoptotic effects of α-tocopherol at nanomolar and micromolar concentrations against 0.2 mM H(2)O(2)-induced toxicity in the PC12 neuronal cell line and to reveal protein kinases that contribute to α-tocopherol protective action. The protection by 100 nM α-tocopherol against H(2)O(2)-induced PC12 cell death was pronounced if the time of pre-incubation with α-tocopherol was 3-18 h. For the first time, the protective effect of α-tocopherol was shown to depend on its concentration in the nanomolar range (1 nM < 10 nM < 100 nM), if the pre-incubation time was 18 h. Nanomolar and micromolar α-tocopherol decreased the number of PC12 cells in late apoptosis induced by H(2)O(2) to the same extent if pre-incubation time was 18 h. Immunoblotting data showed that α-tocopherol markedly diminished the time of maximal activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and protein kinase B (Akt)-induced in PC12 cells by H(2)O(2). Inhibitors of MEK 1/2, PI 3-kinase and protein kinase C (PKC) diminished the protective effect of α-tocopherol against H(2)O(2)-initiated toxicity if the pre-incubation time was long. The modulation of ERK 1/2, Akt and PKC activities appears to participate in the protection by α-tocopherol against H(2)O(2)-induced death of PC12 cells. The data obtained suggest that inhibition by α-tocopherol in late stage ERK 1/2 and Akt activation induced by H(2)O(2) in PC12 cells makes contribution to its protective effect, while total inhibition of these enzymes is not protective.

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Related in: MedlinePlus

The figure shows effect of pre-incubation of PC12 cells with 100 nM and 100 μM α-T for 18 h prior to exposure of cells to 0.3 mM H2O2 on the activity of Akt (pAkt level). The results of five experiments made are shown as means ± SEM. (A) Pre-incubation with 100 nM α-T; (B) Pre-incubation with 100 μM α-T. Red lines with square data points show effect of H2O2 alone, black lines with diamond data points show effect of H2O2 after pre-incubation with α-T. On (A,B): HP = hydrogen peroxide; alpha-T = α-tocopherol. * The differences are significant according to Students’ paired t test as compared to the level of pAkt in the PC12 cells exposed to α-T and H2O2, p < 0.05.
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f10-ijms-13-11543: The figure shows effect of pre-incubation of PC12 cells with 100 nM and 100 μM α-T for 18 h prior to exposure of cells to 0.3 mM H2O2 on the activity of Akt (pAkt level). The results of five experiments made are shown as means ± SEM. (A) Pre-incubation with 100 nM α-T; (B) Pre-incubation with 100 μM α-T. Red lines with square data points show effect of H2O2 alone, black lines with diamond data points show effect of H2O2 after pre-incubation with α-T. On (A,B): HP = hydrogen peroxide; alpha-T = α-tocopherol. * The differences are significant according to Students’ paired t test as compared to the level of pAkt in the PC12 cells exposed to α-T and H2O2, p < 0.05.

Mentions: As Figure 8 shows, in the presence of 10 μM SL327, pERK 1/2 is not revealed in PC12 cells, while in the presence of 50 μM LY294002, pAkt is absent in these cells. The effect of other inhibitors used will be described later (after Figures 9 and 10).


α-Tocopherol at nanomolar concentration protects PC12 cells from hydrogen peroxide-induced death and modulates protein kinase activities.

Zakharova IO, Sokolova TV, Bayunova LV, Vlasova YA, Rychkova MP, Avrova NF - Int J Mol Sci (2012)

The figure shows effect of pre-incubation of PC12 cells with 100 nM and 100 μM α-T for 18 h prior to exposure of cells to 0.3 mM H2O2 on the activity of Akt (pAkt level). The results of five experiments made are shown as means ± SEM. (A) Pre-incubation with 100 nM α-T; (B) Pre-incubation with 100 μM α-T. Red lines with square data points show effect of H2O2 alone, black lines with diamond data points show effect of H2O2 after pre-incubation with α-T. On (A,B): HP = hydrogen peroxide; alpha-T = α-tocopherol. * The differences are significant according to Students’ paired t test as compared to the level of pAkt in the PC12 cells exposed to α-T and H2O2, p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472762&req=5

f10-ijms-13-11543: The figure shows effect of pre-incubation of PC12 cells with 100 nM and 100 μM α-T for 18 h prior to exposure of cells to 0.3 mM H2O2 on the activity of Akt (pAkt level). The results of five experiments made are shown as means ± SEM. (A) Pre-incubation with 100 nM α-T; (B) Pre-incubation with 100 μM α-T. Red lines with square data points show effect of H2O2 alone, black lines with diamond data points show effect of H2O2 after pre-incubation with α-T. On (A,B): HP = hydrogen peroxide; alpha-T = α-tocopherol. * The differences are significant according to Students’ paired t test as compared to the level of pAkt in the PC12 cells exposed to α-T and H2O2, p < 0.05.
Mentions: As Figure 8 shows, in the presence of 10 μM SL327, pERK 1/2 is not revealed in PC12 cells, while in the presence of 50 μM LY294002, pAkt is absent in these cells. The effect of other inhibitors used will be described later (after Figures 9 and 10).

Bottom Line: For the first time, the protective effect of α-tocopherol was shown to depend on its concentration in the nanomolar range (1 nM < 10 nM < 100 nM), if the pre-incubation time was 18 h.Nanomolar and micromolar α-tocopherol decreased the number of PC12 cells in late apoptosis induced by H(2)O(2) to the same extent if pre-incubation time was 18 h.The data obtained suggest that inhibition by α-tocopherol in late stage ERK 1/2 and Akt activation induced by H(2)O(2) in PC12 cells makes contribution to its protective effect, while total inhibition of these enzymes is not protective.

View Article: PubMed Central - PubMed

Affiliation: Department of Comparative Neurochemistry, Institute of Evolutionary Physiology and Biochemistry of Russian Academy of Sciences, Thorez avenue, 44, Saint-Petersburg 194223, Russia; E-Mails: zakhar@iephb.ru (I.O.Z.); sokolt1956@mail.ru (T.V.S.); bayunoval@mail.ru (L.V.B.); yousia@mail.ru (Y.A.V.); involved@mail.ru (M.P.R.).

ABSTRACT
The aim of this work was to compare protective and anti-apoptotic effects of α-tocopherol at nanomolar and micromolar concentrations against 0.2 mM H(2)O(2)-induced toxicity in the PC12 neuronal cell line and to reveal protein kinases that contribute to α-tocopherol protective action. The protection by 100 nM α-tocopherol against H(2)O(2)-induced PC12 cell death was pronounced if the time of pre-incubation with α-tocopherol was 3-18 h. For the first time, the protective effect of α-tocopherol was shown to depend on its concentration in the nanomolar range (1 nM < 10 nM < 100 nM), if the pre-incubation time was 18 h. Nanomolar and micromolar α-tocopherol decreased the number of PC12 cells in late apoptosis induced by H(2)O(2) to the same extent if pre-incubation time was 18 h. Immunoblotting data showed that α-tocopherol markedly diminished the time of maximal activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and protein kinase B (Akt)-induced in PC12 cells by H(2)O(2). Inhibitors of MEK 1/2, PI 3-kinase and protein kinase C (PKC) diminished the protective effect of α-tocopherol against H(2)O(2)-initiated toxicity if the pre-incubation time was long. The modulation of ERK 1/2, Akt and PKC activities appears to participate in the protection by α-tocopherol against H(2)O(2)-induced death of PC12 cells. The data obtained suggest that inhibition by α-tocopherol in late stage ERK 1/2 and Akt activation induced by H(2)O(2) in PC12 cells makes contribution to its protective effect, while total inhibition of these enzymes is not protective.

Show MeSH
Related in: MedlinePlus