Limits...
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.

Show MeSH

Related in: MedlinePlus

The figure shows the effect of pre-incubation for 18 h with α-T, prior to PC12 cell exposure to 0.2 mM H2O2 for 24 h on the relative number of PC12 cells in late apoptosis (% of the total cell number). The results of one typical experiment from 5 replicates are presented. The relative value of subG1 hypodiploid peak (left on the histograms) corresponds to the relative number of PC12 cells in late apoptosis. In the figure: (A) control; (B) H2O2; (C) H2O2 + pre-incubation with 50 μM α-T; (D) H2O2 + pre-incubation with 100 nM α-T. In the control sample, the relative number of cells in late apoptosis (A) is lower than 1%, but exposure to H2O2 increases this peak to 32% (B). However, pre-incubation with 50 μM and 100 nM α-T decreases the relative value of the subG1 hypodiploid peak from 32% (B) to 3% and 4% of the total cell number, respectively (C,D).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5-ijms-13-11543: The figure shows the effect of pre-incubation for 18 h with α-T, prior to PC12 cell exposure to 0.2 mM H2O2 for 24 h on the relative number of PC12 cells in late apoptosis (% of the total cell number). The results of one typical experiment from 5 replicates are presented. The relative value of subG1 hypodiploid peak (left on the histograms) corresponds to the relative number of PC12 cells in late apoptosis. In the figure: (A) control; (B) H2O2; (C) H2O2 + pre-incubation with 50 μM α-T; (D) H2O2 + pre-incubation with 100 nM α-T. In the control sample, the relative number of cells in late apoptosis (A) is lower than 1%, but exposure to H2O2 increases this peak to 32% (B). However, pre-incubation with 50 μM and 100 nM α-T decreases the relative value of the subG1 hypodiploid peak from 32% (B) to 3% and 4% of the total cell number, respectively (C,D).

Mentions: The anti-apoptotic effect of α-T was studied using cell staining with propidium iodide and flow cytometric analysis. The relative value of subG1 hypodiploid peak (left on the histograms) corresponds to the relative number of PC12 cells in late apoptosis. We compared the effect of short (0.5 h) and long (18 h) pre-incubation of PC12 cells with 100 nM and 50 μM α-T prior to their exposure to 0.2 mM hydrogen peroxide for 24 h (Figures 4 and 5, respectively).


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 for 18 h with α-T, prior to PC12 cell exposure to 0.2 mM H2O2 for 24 h on the relative number of PC12 cells in late apoptosis (% of the total cell number). The results of one typical experiment from 5 replicates are presented. The relative value of subG1 hypodiploid peak (left on the histograms) corresponds to the relative number of PC12 cells in late apoptosis. In the figure: (A) control; (B) H2O2; (C) H2O2 + pre-incubation with 50 μM α-T; (D) H2O2 + pre-incubation with 100 nM α-T. In the control sample, the relative number of cells in late apoptosis (A) is lower than 1%, but exposure to H2O2 increases this peak to 32% (B). However, pre-incubation with 50 μM and 100 nM α-T decreases the relative value of the subG1 hypodiploid peak from 32% (B) to 3% and 4% of the total cell number, respectively (C,D).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5-ijms-13-11543: The figure shows the effect of pre-incubation for 18 h with α-T, prior to PC12 cell exposure to 0.2 mM H2O2 for 24 h on the relative number of PC12 cells in late apoptosis (% of the total cell number). The results of one typical experiment from 5 replicates are presented. The relative value of subG1 hypodiploid peak (left on the histograms) corresponds to the relative number of PC12 cells in late apoptosis. In the figure: (A) control; (B) H2O2; (C) H2O2 + pre-incubation with 50 μM α-T; (D) H2O2 + pre-incubation with 100 nM α-T. In the control sample, the relative number of cells in late apoptosis (A) is lower than 1%, but exposure to H2O2 increases this peak to 32% (B). However, pre-incubation with 50 μM and 100 nM α-T decreases the relative value of the subG1 hypodiploid peak from 32% (B) to 3% and 4% of the total cell number, respectively (C,D).
Mentions: The anti-apoptotic effect of α-T was studied using cell staining with propidium iodide and flow cytometric analysis. The relative value of subG1 hypodiploid peak (left on the histograms) corresponds to the relative number of PC12 cells in late apoptosis. We compared the effect of short (0.5 h) and long (18 h) pre-incubation of PC12 cells with 100 nM and 50 μM α-T prior to their exposure to 0.2 mM hydrogen peroxide for 24 h (Figures 4 and 5, respectively).

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