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Ginkgo biloba extract ameliorates oxidative phosphorylation performance and rescues abeta-induced failure.

Rhein V, Giese M, Baysang G, Meier F, Rao S, Schulz KL, Hamburger M, Eckert A - PLoS ONE (2010)

Bottom Line: We observed a general antioxidant effect of GBE leading to an increase of the coupling state of mitochondria as well as energy homeostasis and a reduction of ROS levels in control cells and in APP cells.GBE effect on OXPHOS was even preserved in mitochondria after isolation from treated cells.Although the underlying molecular mechanisms of the mode of action of GBE remain to be determined, our study clearly highlights the beneficial effect of GBE on the cellular OXPHOS performance and restoration of Abeta-induced mitochondrial dysfunction.

View Article: PubMed Central - PubMed

Affiliation: Neurobiology Laboratory for Brain Aging and Mental Health, Psychiatric University Clinics, University of Basel, Basel, Switzerland.

ABSTRACT

Background: Energy deficiency and mitochondrial failure have been recognized as a prominent, early event in Alzheimer's disease (AD). Recently, we demonstrated that chronic exposure to amyloid-beta (Abeta) in human neuroblastoma cells over-expressing human wild-type amyloid precursor protein (APP) resulted in (i) activity changes of complexes III and IV of the oxidative phosphorylation system (OXPHOS) and in (ii) a drop of ATP levels which may finally instigate loss of synapses and neuronal cell death in AD. Therefore, the aim of the present study was to investigate whether standardized Ginkgo biloba extract LI 1370 (GBE) is able to rescue Abeta-induced defects in energy metabolism.

Methodology/principal findings: We used a high-resolution respiratory protocol to evaluate OXPHOS respiratory capacity under physiological condition in control (stably transfected with the empty vector) and APP cells after treatment with GBE. In addition, oxygen consumption of isolated mitochondria, activities of mitochondrial respiratory enzymes, ATP and reactive oxygen species (ROS) levels as well as mitochondrial membrane mass and mitochondrial DNA content were determined. We observed a general antioxidant effect of GBE leading to an increase of the coupling state of mitochondria as well as energy homeostasis and a reduction of ROS levels in control cells and in APP cells. GBE effect on OXPHOS was even preserved in mitochondria after isolation from treated cells. Moreover, these functional data were paralleled by an up-regulation of mitochondrial DNA. Improvement of the OXPHOS efficiency was stronger in APP cells than in control cells. In APP cells, the GBE-induced amelioration of oxygen consumption most likely arose from the modulation and respective normalization of the Abeta-induced disturbance in the activity of mitochondrial complexes III and IV restoring impaired ATP levels possibly through decreasing Abeta and oxidative stress level.

Conclusions/significance: Although the underlying molecular mechanisms of the mode of action of GBE remain to be determined, our study clearly highlights the beneficial effect of GBE on the cellular OXPHOS performance and restoration of Abeta-induced mitochondrial dysfunction.

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Related in: MedlinePlus

GBE modulated mitochondrial flux control ratios and rose ATP synthesis.A) Respiratory control ratio (RCR) represents the mitochondrial coupling state. RCR was decreased in APP cells and increased in GBE-treated control and APP cells. B) ROX/ETS yields an index of the magnitude of residual oxygen consumption relative to the maximum oxygen consumption capacity. This ratio was decreased in GBE-treated control and APP cells. C) ATP levels were decreased in APP cells and increased in GBE-treated control and APP cells. (A–C) Values represent the means ± S.E., GBE treatment effect, paired student's t-test, number of pairs n = 5: #, p<0.05, ##, p<0.01 GBE treated versus corresponding untreated cells; and effect of Aβ, unpaired student's t-test, n = 5, *, p<0.05; ***, p<0.001 APP versus control cells.
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pone-0012359-g003: GBE modulated mitochondrial flux control ratios and rose ATP synthesis.A) Respiratory control ratio (RCR) represents the mitochondrial coupling state. RCR was decreased in APP cells and increased in GBE-treated control and APP cells. B) ROX/ETS yields an index of the magnitude of residual oxygen consumption relative to the maximum oxygen consumption capacity. This ratio was decreased in GBE-treated control and APP cells. C) ATP levels were decreased in APP cells and increased in GBE-treated control and APP cells. (A–C) Values represent the means ± S.E., GBE treatment effect, paired student's t-test, number of pairs n = 5: #, p<0.05, ##, p<0.01 GBE treated versus corresponding untreated cells; and effect of Aβ, unpaired student's t-test, n = 5, *, p<0.05; ***, p<0.001 APP versus control cells.

Mentions: To analyse the impact of GBE on metabolic states of mitochondrial respiration, two flux control ratios have been evaluated. First, the respiratory control ratio (RCR) which is an indicator of the coupling state of mitochondria was determined. State 3 is the rate of phosphorylating respiration in the presence of exogenous ADP, when mitochondria are actively making ATP, whereas state 4 is the rate of resting respiration, when all ADP has been consumed. State 4 is associated with proton leakage across the inner mitochondrial membrane, when mitochondria exhibit basal activity, i.e. they are respiring but not making ATP. Therefore, RCR represents the ADP-activated flux to measure coupled OXPHOS capacity (state3) divided by leak flux (state4). Whereas increased Aβ levels led to a decrease of RCR in APP cells, treatment with GBE significantly increased the ratio in both cell types (Fig. 3A). Secondly, ROX/ETS yields an index of the magnitude of residual oxygen consumption relative to maximum oxygen consumption capacity. This ratio was decreased in both cell types after treatment with GBE with the strongest effect in APP cells (Fig. 3B). Both flux control ratio changes indicate an increase of the coupling state of mitochondria leading to a better efficiency of OXPHOS. Consistent with this result, we observed a rise of ATP levels which are closely correlated with a higher complex V activity, the final OXPHOS enzyme, in GBE-treated control and APP cells (Fig. 3C).


Ginkgo biloba extract ameliorates oxidative phosphorylation performance and rescues abeta-induced failure.

Rhein V, Giese M, Baysang G, Meier F, Rao S, Schulz KL, Hamburger M, Eckert A - PLoS ONE (2010)

GBE modulated mitochondrial flux control ratios and rose ATP synthesis.A) Respiratory control ratio (RCR) represents the mitochondrial coupling state. RCR was decreased in APP cells and increased in GBE-treated control and APP cells. B) ROX/ETS yields an index of the magnitude of residual oxygen consumption relative to the maximum oxygen consumption capacity. This ratio was decreased in GBE-treated control and APP cells. C) ATP levels were decreased in APP cells and increased in GBE-treated control and APP cells. (A–C) Values represent the means ± S.E., GBE treatment effect, paired student's t-test, number of pairs n = 5: #, p<0.05, ##, p<0.01 GBE treated versus corresponding untreated cells; and effect of Aβ, unpaired student's t-test, n = 5, *, p<0.05; ***, p<0.001 APP versus control cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2927422&req=5

pone-0012359-g003: GBE modulated mitochondrial flux control ratios and rose ATP synthesis.A) Respiratory control ratio (RCR) represents the mitochondrial coupling state. RCR was decreased in APP cells and increased in GBE-treated control and APP cells. B) ROX/ETS yields an index of the magnitude of residual oxygen consumption relative to the maximum oxygen consumption capacity. This ratio was decreased in GBE-treated control and APP cells. C) ATP levels were decreased in APP cells and increased in GBE-treated control and APP cells. (A–C) Values represent the means ± S.E., GBE treatment effect, paired student's t-test, number of pairs n = 5: #, p<0.05, ##, p<0.01 GBE treated versus corresponding untreated cells; and effect of Aβ, unpaired student's t-test, n = 5, *, p<0.05; ***, p<0.001 APP versus control cells.
Mentions: To analyse the impact of GBE on metabolic states of mitochondrial respiration, two flux control ratios have been evaluated. First, the respiratory control ratio (RCR) which is an indicator of the coupling state of mitochondria was determined. State 3 is the rate of phosphorylating respiration in the presence of exogenous ADP, when mitochondria are actively making ATP, whereas state 4 is the rate of resting respiration, when all ADP has been consumed. State 4 is associated with proton leakage across the inner mitochondrial membrane, when mitochondria exhibit basal activity, i.e. they are respiring but not making ATP. Therefore, RCR represents the ADP-activated flux to measure coupled OXPHOS capacity (state3) divided by leak flux (state4). Whereas increased Aβ levels led to a decrease of RCR in APP cells, treatment with GBE significantly increased the ratio in both cell types (Fig. 3A). Secondly, ROX/ETS yields an index of the magnitude of residual oxygen consumption relative to maximum oxygen consumption capacity. This ratio was decreased in both cell types after treatment with GBE with the strongest effect in APP cells (Fig. 3B). Both flux control ratio changes indicate an increase of the coupling state of mitochondria leading to a better efficiency of OXPHOS. Consistent with this result, we observed a rise of ATP levels which are closely correlated with a higher complex V activity, the final OXPHOS enzyme, in GBE-treated control and APP cells (Fig. 3C).

Bottom Line: We observed a general antioxidant effect of GBE leading to an increase of the coupling state of mitochondria as well as energy homeostasis and a reduction of ROS levels in control cells and in APP cells.GBE effect on OXPHOS was even preserved in mitochondria after isolation from treated cells.Although the underlying molecular mechanisms of the mode of action of GBE remain to be determined, our study clearly highlights the beneficial effect of GBE on the cellular OXPHOS performance and restoration of Abeta-induced mitochondrial dysfunction.

View Article: PubMed Central - PubMed

Affiliation: Neurobiology Laboratory for Brain Aging and Mental Health, Psychiatric University Clinics, University of Basel, Basel, Switzerland.

ABSTRACT

Background: Energy deficiency and mitochondrial failure have been recognized as a prominent, early event in Alzheimer's disease (AD). Recently, we demonstrated that chronic exposure to amyloid-beta (Abeta) in human neuroblastoma cells over-expressing human wild-type amyloid precursor protein (APP) resulted in (i) activity changes of complexes III and IV of the oxidative phosphorylation system (OXPHOS) and in (ii) a drop of ATP levels which may finally instigate loss of synapses and neuronal cell death in AD. Therefore, the aim of the present study was to investigate whether standardized Ginkgo biloba extract LI 1370 (GBE) is able to rescue Abeta-induced defects in energy metabolism.

Methodology/principal findings: We used a high-resolution respiratory protocol to evaluate OXPHOS respiratory capacity under physiological condition in control (stably transfected with the empty vector) and APP cells after treatment with GBE. In addition, oxygen consumption of isolated mitochondria, activities of mitochondrial respiratory enzymes, ATP and reactive oxygen species (ROS) levels as well as mitochondrial membrane mass and mitochondrial DNA content were determined. We observed a general antioxidant effect of GBE leading to an increase of the coupling state of mitochondria as well as energy homeostasis and a reduction of ROS levels in control cells and in APP cells. GBE effect on OXPHOS was even preserved in mitochondria after isolation from treated cells. Moreover, these functional data were paralleled by an up-regulation of mitochondrial DNA. Improvement of the OXPHOS efficiency was stronger in APP cells than in control cells. In APP cells, the GBE-induced amelioration of oxygen consumption most likely arose from the modulation and respective normalization of the Abeta-induced disturbance in the activity of mitochondrial complexes III and IV restoring impaired ATP levels possibly through decreasing Abeta and oxidative stress level.

Conclusions/significance: Although the underlying molecular mechanisms of the mode of action of GBE remain to be determined, our study clearly highlights the beneficial effect of GBE on the cellular OXPHOS performance and restoration of Abeta-induced mitochondrial dysfunction.

Show MeSH
Related in: MedlinePlus