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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 the effects of pre-incubation with α-T for 0.5 and 18 h prior to PC12 cell exposure to 1 mM H2O2 for 3 h. (A) Pre-incubation with α-T at various concentrations for 0.5 h; (B) Pre-incubation with 100 nM and 100 μM α-T for 18 h. In this figure, the results of one typical experiment (from five experiments made) are presented as means ± SEM of 2–3 parallel determinations. The differences are significant by one-way ANOVA followed by Tukey’s multiple comparison test: * as compared to control values, p < 0.01; x as compared to the effect of H2O2 alone, p < 0.05; # as compared to the effect of α-T at all higher concentrations, p < 0.01. The data obtained provide evidence that pre-incubation with nanomolar α-T for 0.5 h prior to cell exposure to 1 mM H2O2 is not protective against H2O2-induced toxicity, while micromolar α-T is protective (A). However, if PC12 cells are pre-incubated with 100 nM or 100 μM α-T for 18 h and then exposed to 1 mM H2O2 (B) the protective effect of α-T in both concentrations is similar and significant (B).
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f3-ijms-13-11543: The figure shows the effects of pre-incubation with α-T for 0.5 and 18 h prior to PC12 cell exposure to 1 mM H2O2 for 3 h. (A) Pre-incubation with α-T at various concentrations for 0.5 h; (B) Pre-incubation with 100 nM and 100 μM α-T for 18 h. In this figure, the results of one typical experiment (from five experiments made) are presented as means ± SEM of 2–3 parallel determinations. The differences are significant by one-way ANOVA followed by Tukey’s multiple comparison test: * as compared to control values, p < 0.01; x as compared to the effect of H2O2 alone, p < 0.05; # as compared to the effect of α-T at all higher concentrations, p < 0.01. The data obtained provide evidence that pre-incubation with nanomolar α-T for 0.5 h prior to cell exposure to 1 mM H2O2 is not protective against H2O2-induced toxicity, while micromolar α-T is protective (A). However, if PC12 cells are pre-incubated with 100 nM or 100 μM α-T for 18 h and then exposed to 1 mM H2O2 (B) the protective effect of α-T in both concentrations is similar and significant (B).

Mentions: We were interested to find out if α-T at nanomolar concentration was protective following short pre-incubation (0.5 h) and a short (3 h) exposure of 1 mM H2O2. It is to be emphasized that we used the cell exposure to 1 mM H2O2 for 3 h only in a very limited number of experiments presented in Figure 3. In all other figures and tables presented, the results of experiments were made using cell exposure to 0.2 mM H2O2 for 24 h.


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 the effects of pre-incubation with α-T for 0.5 and 18 h prior to PC12 cell exposure to 1 mM H2O2 for 3 h. (A) Pre-incubation with α-T at various concentrations for 0.5 h; (B) Pre-incubation with 100 nM and 100 μM α-T for 18 h. In this figure, the results of one typical experiment (from five experiments made) are presented as means ± SEM of 2–3 parallel determinations. The differences are significant by one-way ANOVA followed by Tukey’s multiple comparison test: * as compared to control values, p < 0.01; x as compared to the effect of H2O2 alone, p < 0.05; # as compared to the effect of α-T at all higher concentrations, p < 0.01. The data obtained provide evidence that pre-incubation with nanomolar α-T for 0.5 h prior to cell exposure to 1 mM H2O2 is not protective against H2O2-induced toxicity, while micromolar α-T is protective (A). However, if PC12 cells are pre-incubated with 100 nM or 100 μM α-T for 18 h and then exposed to 1 mM H2O2 (B) the protective effect of α-T in both concentrations is similar and significant (B).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3-ijms-13-11543: The figure shows the effects of pre-incubation with α-T for 0.5 and 18 h prior to PC12 cell exposure to 1 mM H2O2 for 3 h. (A) Pre-incubation with α-T at various concentrations for 0.5 h; (B) Pre-incubation with 100 nM and 100 μM α-T for 18 h. In this figure, the results of one typical experiment (from five experiments made) are presented as means ± SEM of 2–3 parallel determinations. The differences are significant by one-way ANOVA followed by Tukey’s multiple comparison test: * as compared to control values, p < 0.01; x as compared to the effect of H2O2 alone, p < 0.05; # as compared to the effect of α-T at all higher concentrations, p < 0.01. The data obtained provide evidence that pre-incubation with nanomolar α-T for 0.5 h prior to cell exposure to 1 mM H2O2 is not protective against H2O2-induced toxicity, while micromolar α-T is protective (A). However, if PC12 cells are pre-incubated with 100 nM or 100 μM α-T for 18 h and then exposed to 1 mM H2O2 (B) the protective effect of α-T in both concentrations is similar and significant (B).
Mentions: We were interested to find out if α-T at nanomolar concentration was protective following short pre-incubation (0.5 h) and a short (3 h) exposure of 1 mM H2O2. It is to be emphasized that we used the cell exposure to 1 mM H2O2 for 3 h only in a very limited number of experiments presented in Figure 3. In all other figures and tables presented, the results of experiments were made using cell exposure to 0.2 mM H2O2 for 24 h.

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