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Differential effects of iodoacetamide and iodoacetate on glycolysis and glutathione metabolism of cultured astrocytes.

Schmidt MM, Dringen R - Front Neuroenergetics (2009)

Bottom Line: However, the two thiol reagents differed substantially in their potential to deprive cellular GSH and to inhibit astrocytic glycolysis.IAA depleted the cellular GSH content more efficiently than IA as demonstrated by half-maximal effects for IAA and IA that were observed at concentrations of about 10 and 100 muM, respectively.In contrast, IA was highly efficient in inactivating GAPDH and lactate production with half-maximal effects observed already at a concentration below 100 muM, whereas IAA had to be applied in 10 times higher concentration to inhibit lactate production by 50%.

View Article: PubMed Central - PubMed

Affiliation: Center for Biomolecular Interactions Bremen, University of Bremen Bremen, Germany.

ABSTRACT
Iodoacetamide (IAA) and iodoacetate (IA) have frequently been used to inhibit glycolysis, since these compounds are known for their ability to irreversibly inhibit the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). However, the consequences of a treatment with such thiol reagents on the glutathione (GSH) metabolism of brain cells have not been explored. Exposure of astroglia-rich primary cultures to IAA or IA in concentrations of up to 1 mM deprived the cells of GSH, inhibited cellular GAPDH activity, lowered cellular lactate production and caused a delayed cell death that was detectable after 90 min of incubation. However, the two thiol reagents differed substantially in their potential to deprive cellular GSH and to inhibit astrocytic glycolysis. IAA depleted the cellular GSH content more efficiently than IA as demonstrated by half-maximal effects for IAA and IA that were observed at concentrations of about 10 and 100 muM, respectively. In contrast, IA was highly efficient in inactivating GAPDH and lactate production with half-maximal effects observed already at a concentration below 100 muM, whereas IAA had to be applied in 10 times higher concentration to inhibit lactate production by 50%. These substantial differences of IAA and IA to affect GSH content and glycolysis of cultured astrocytes suggest that in order to inhibit astrocytic glycolysis without substantially compromising the cellular GSH metabolism, IA - and not IAA - should be used in low concentrations and/or for short incubation periods.

No MeSH data available.


Related in: MedlinePlus

Consequences of an application of IAA (A) or IA (B) on the extracellular lactate concentration in astrocyte cultures. The cells were incubated for up to 120 min without or with IAA or IA in the concentrations indicated in (A) and (B). The results represent mean ± SD of data that were obtained on three independently prepared cultures. The cultures contained initial protein contents of 80 ± 8 μg protein per well. The significance of differences to the data obtained for the control condition (absence of inhibitor) are indicated by *p < 0.05, **p < 0.01 or ***p < 0.001.
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Figure 6: Consequences of an application of IAA (A) or IA (B) on the extracellular lactate concentration in astrocyte cultures. The cells were incubated for up to 120 min without or with IAA or IA in the concentrations indicated in (A) and (B). The results represent mean ± SD of data that were obtained on three independently prepared cultures. The cultures contained initial protein contents of 80 ± 8 μg protein per well. The significance of differences to the data obtained for the control condition (absence of inhibitor) are indicated by *p < 0.05, **p < 0.01 or ***p < 0.001.

Mentions: Exposure of astrocytes to IAA hardly affected the extracellular accumulation of lactate during the first 60 min of incubation compared to control (Figure 6A), whereas a further increase of extracellular lactate was slowed during longer incubations, at least for IAA concentrations of 0.3 and 1 mM (Figure 6A). The extracellular lactate concentration determined for cells that were treated with IAA for 60 min did not differ significantly to that of control cells (Figure 7A). In contrast, incubation of astrocytes with IA in a concentration of 1 mM inhibited extracellular lactate accumulation much quicker than IAA (Figure 6B). In concentrations of 0.1 or 0.3 mM IA almost completely prevented extracellular lactate accumulation within 30 min of incubation (Figure 6B). After 60 min of incubation the extracellular lactate concentrations of astrocyte cultures that were treated with 0.1, 0.3 and 1 mM IA were significantly lowered to 40 ± 7, 24 ± 16 and 6 ± 8%, respectively, of the concentration determined for cells that were incubated without inhibitor (Figure 7A).


Differential effects of iodoacetamide and iodoacetate on glycolysis and glutathione metabolism of cultured astrocytes.

Schmidt MM, Dringen R - Front Neuroenergetics (2009)

Consequences of an application of IAA (A) or IA (B) on the extracellular lactate concentration in astrocyte cultures. The cells were incubated for up to 120 min without or with IAA or IA in the concentrations indicated in (A) and (B). The results represent mean ± SD of data that were obtained on three independently prepared cultures. The cultures contained initial protein contents of 80 ± 8 μg protein per well. The significance of differences to the data obtained for the control condition (absence of inhibitor) are indicated by *p < 0.05, **p < 0.01 or ***p < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2691547&req=5

Figure 6: Consequences of an application of IAA (A) or IA (B) on the extracellular lactate concentration in astrocyte cultures. The cells were incubated for up to 120 min without or with IAA or IA in the concentrations indicated in (A) and (B). The results represent mean ± SD of data that were obtained on three independently prepared cultures. The cultures contained initial protein contents of 80 ± 8 μg protein per well. The significance of differences to the data obtained for the control condition (absence of inhibitor) are indicated by *p < 0.05, **p < 0.01 or ***p < 0.001.
Mentions: Exposure of astrocytes to IAA hardly affected the extracellular accumulation of lactate during the first 60 min of incubation compared to control (Figure 6A), whereas a further increase of extracellular lactate was slowed during longer incubations, at least for IAA concentrations of 0.3 and 1 mM (Figure 6A). The extracellular lactate concentration determined for cells that were treated with IAA for 60 min did not differ significantly to that of control cells (Figure 7A). In contrast, incubation of astrocytes with IA in a concentration of 1 mM inhibited extracellular lactate accumulation much quicker than IAA (Figure 6B). In concentrations of 0.1 or 0.3 mM IA almost completely prevented extracellular lactate accumulation within 30 min of incubation (Figure 6B). After 60 min of incubation the extracellular lactate concentrations of astrocyte cultures that were treated with 0.1, 0.3 and 1 mM IA were significantly lowered to 40 ± 7, 24 ± 16 and 6 ± 8%, respectively, of the concentration determined for cells that were incubated without inhibitor (Figure 7A).

Bottom Line: However, the two thiol reagents differed substantially in their potential to deprive cellular GSH and to inhibit astrocytic glycolysis.IAA depleted the cellular GSH content more efficiently than IA as demonstrated by half-maximal effects for IAA and IA that were observed at concentrations of about 10 and 100 muM, respectively.In contrast, IA was highly efficient in inactivating GAPDH and lactate production with half-maximal effects observed already at a concentration below 100 muM, whereas IAA had to be applied in 10 times higher concentration to inhibit lactate production by 50%.

View Article: PubMed Central - PubMed

Affiliation: Center for Biomolecular Interactions Bremen, University of Bremen Bremen, Germany.

ABSTRACT
Iodoacetamide (IAA) and iodoacetate (IA) have frequently been used to inhibit glycolysis, since these compounds are known for their ability to irreversibly inhibit the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). However, the consequences of a treatment with such thiol reagents on the glutathione (GSH) metabolism of brain cells have not been explored. Exposure of astroglia-rich primary cultures to IAA or IA in concentrations of up to 1 mM deprived the cells of GSH, inhibited cellular GAPDH activity, lowered cellular lactate production and caused a delayed cell death that was detectable after 90 min of incubation. However, the two thiol reagents differed substantially in their potential to deprive cellular GSH and to inhibit astrocytic glycolysis. IAA depleted the cellular GSH content more efficiently than IA as demonstrated by half-maximal effects for IAA and IA that were observed at concentrations of about 10 and 100 muM, respectively. In contrast, IA was highly efficient in inactivating GAPDH and lactate production with half-maximal effects observed already at a concentration below 100 muM, whereas IAA had to be applied in 10 times higher concentration to inhibit lactate production by 50%. These substantial differences of IAA and IA to affect GSH content and glycolysis of cultured astrocytes suggest that in order to inhibit astrocytic glycolysis without substantially compromising the cellular GSH metabolism, IA - and not IAA - should be used in low concentrations and/or for short incubation periods.

No MeSH data available.


Related in: MedlinePlus