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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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The figure shows the effect of pre-incubation of immature cortical neurons with nanomolar and micromolar α-T for 0.5 and 18 h on the viability of these cells exposed to hydrogen peroxide. The results of one typical experiment (n = 6) are presented as means ± SEM of 3–4 parallel determinations. The neurons were isolated from the brain cortex of an embryonic rat brain as described under Experimental procedure. After 6 days in culture (at the 7th day in vitro) immature cortical neurons were pre-incubated for 0.5 h (A) or 18 h (B) with α-T and then exposed to 0.2 mM H2O2 for 24 h. 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 < 0.01; # as compared to the effect of H2O2 and 50 μM α-T, p < 0.05.
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f6-ijms-13-11543: The figure shows the effect of pre-incubation of immature cortical neurons with nanomolar and micromolar α-T for 0.5 and 18 h on the viability of these cells exposed to hydrogen peroxide. The results of one typical experiment (n = 6) are presented as means ± SEM of 3–4 parallel determinations. The neurons were isolated from the brain cortex of an embryonic rat brain as described under Experimental procedure. After 6 days in culture (at the 7th day in vitro) immature cortical neurons were pre-incubated for 0.5 h (A) or 18 h (B) with α-T and then exposed to 0.2 mM H2O2 for 24 h. 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 < 0.01; # as compared to the effect of H2O2 and 50 μM α-T, p < 0.05.

Mentions: The protective effect of pre-incubation of immature cortical neurons with 100 nM and 50 μM α-T for 18 h prior to their exposure to H2O2 was found to be pronounced and similar (Figure 6B). However, pre-incubation of cortical neurons for 0.5 h with 100 nM α-T is not effective, while pre-incubation for 0.5 h with 50 μM α-T increases the viability of immature neurons to a great extent (Figure 6A,B).


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 effect of pre-incubation of immature cortical neurons with nanomolar and micromolar α-T for 0.5 and 18 h on the viability of these cells exposed to hydrogen peroxide. The results of one typical experiment (n = 6) are presented as means ± SEM of 3–4 parallel determinations. The neurons were isolated from the brain cortex of an embryonic rat brain as described under Experimental procedure. After 6 days in culture (at the 7th day in vitro) immature cortical neurons were pre-incubated for 0.5 h (A) or 18 h (B) with α-T and then exposed to 0.2 mM H2O2 for 24 h. 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 < 0.01; # as compared to the effect of H2O2 and 50 μM α-T, p < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6-ijms-13-11543: The figure shows the effect of pre-incubation of immature cortical neurons with nanomolar and micromolar α-T for 0.5 and 18 h on the viability of these cells exposed to hydrogen peroxide. The results of one typical experiment (n = 6) are presented as means ± SEM of 3–4 parallel determinations. The neurons were isolated from the brain cortex of an embryonic rat brain as described under Experimental procedure. After 6 days in culture (at the 7th day in vitro) immature cortical neurons were pre-incubated for 0.5 h (A) or 18 h (B) with α-T and then exposed to 0.2 mM H2O2 for 24 h. 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 < 0.01; # as compared to the effect of H2O2 and 50 μM α-T, p < 0.05.
Mentions: The protective effect of pre-incubation of immature cortical neurons with 100 nM and 50 μM α-T for 18 h prior to their exposure to H2O2 was found to be pronounced and similar (Figure 6B). However, pre-incubation of cortical neurons for 0.5 h with 100 nM α-T is not effective, while pre-incubation for 0.5 h with 50 μM α-T increases the viability of immature neurons to a great extent (Figure 6A,B).

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