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Chronic vitamin C deficiency promotes redox imbalance in the brain but does not alter sodium-dependent vitamin C transporter 2 expression.

Paidi MD, Schjoldager JG, Lykkesfeldt J, Tveden-Nyborg P - Nutrients (2014)

Bottom Line: Biochemical analyses demonstrated significantly decreased total VitC and an increased percentage of dehydroascorbic acid, as well as increased lipid oxidation (malondialdehyde), in the brains of VitC deficient animals (p < 0.0001) compared to controls.No significant changes were detected in either gene or protein expression of SVCT2 between groups or brain regions.In conclusion, chronic pre-and postnatal VitC deficiency increased brain redox imbalance but did not increase SVCT2 expression.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C 1870, Denmark. maypa@sund.ku.dk.

ABSTRACT
Vitamin C (VitC) has several roles in the brain acting both as a specific and non-specific antioxidant. The brain upholds a very high VitC concentration and is able to preferentially retain VitC even during deficiency. The accumulation of brain VitC levels much higher than in blood is primarily achieved by the sodium dependent VitC transporter (SVCT2). This study investigated the effects of chronic pre-and postnatal VitC deficiency as well as the effects of postnatal VitC repletion, on brain SVCT2 expression and markers of oxidative stress in young guinea pigs. Biochemical analyses demonstrated significantly decreased total VitC and an increased percentage of dehydroascorbic acid, as well as increased lipid oxidation (malondialdehyde), in the brains of VitC deficient animals (p < 0.0001) compared to controls. VitC repleted animals were not significantly different from controls. No significant changes were detected in either gene or protein expression of SVCT2 between groups or brain regions. In conclusion, chronic pre-and postnatal VitC deficiency increased brain redox imbalance but did not increase SVCT2 expression. Our findings show potential implications for VitC deficiency induced negative effects of redox imbalance in the brain and provide novel insight to the regulation of VitC in the brain during deficiency.

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Related in: MedlinePlus

Specificity of anti-SVCT2 in Western blot. (A) Specificity of anti-SVCT2 without pre-absorption of antibody with blocking peptide in guinea pig (Gp) brain lysates (HP, BFC, and BC, respectively) seen as a doublet above 60 kDa and in mouse (M) brain lysates as a single band at 60 kDa; (B) Show brain lysates of Gp and M with pre-absorption of antibody with blocking peptide. Block arrow show the non-specific band detected in western blots in a few guinea pig brain lysates. Western blot standard ladder (Std) and band lengths are displayed for both blots.
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nutrients-06-01809-f002: Specificity of anti-SVCT2 in Western blot. (A) Specificity of anti-SVCT2 without pre-absorption of antibody with blocking peptide in guinea pig (Gp) brain lysates (HP, BFC, and BC, respectively) seen as a doublet above 60 kDa and in mouse (M) brain lysates as a single band at 60 kDa; (B) Show brain lysates of Gp and M with pre-absorption of antibody with blocking peptide. Block arrow show the non-specific band detected in western blots in a few guinea pig brain lysates. Western blot standard ladder (Std) and band lengths are displayed for both blots.

Mentions: The PCR analysis of SVCT2 expression from HP displayed a tendency to increase in DEF animals, but this was not significant (Figure 1A). No significant differences were observed in either BC or BFC regions between the three groups (Figure 1B,C). Western blot was performed to investigate if VitC deficiency affected SVCT2 protein levels from the three brain regions. Samples resulted in a doublet that may correspond to glycosylated and non-glycosylated forms (bands above 60 kDa and ~70 kDa) (Figure 2A), as has been previously reported [32,33]. Incubation with antibody specific blocking peptide successfully prevented both bands (Figure 2B), confirming specificity of the SVCT2 antibody in both guinea pig and mouse (positive control) lysates (Figure 2A,B). A few brain lysates gave rise to an additional 80 kDa band following anti-SVCT2 blots. This was detected even after pre-absorption with blocking peptide, confirming it to be a non-specific band (Figure 2B). Although we did not quantify band density between the three regions of the brain, hippocampus samples generally appeared to display intense bands compared to the samples from the other two brain regions with the faintest bands pertaining to samples from BFC. No significant changes in protein expression were found between the three dietary groups within the measured brain regions (Figure 3) suggesting that SVCT2 expression is not induced by the dietary regimes applied in this study.


Chronic vitamin C deficiency promotes redox imbalance in the brain but does not alter sodium-dependent vitamin C transporter 2 expression.

Paidi MD, Schjoldager JG, Lykkesfeldt J, Tveden-Nyborg P - Nutrients (2014)

Specificity of anti-SVCT2 in Western blot. (A) Specificity of anti-SVCT2 without pre-absorption of antibody with blocking peptide in guinea pig (Gp) brain lysates (HP, BFC, and BC, respectively) seen as a doublet above 60 kDa and in mouse (M) brain lysates as a single band at 60 kDa; (B) Show brain lysates of Gp and M with pre-absorption of antibody with blocking peptide. Block arrow show the non-specific band detected in western blots in a few guinea pig brain lysates. Western blot standard ladder (Std) and band lengths are displayed for both blots.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4042571&req=5

nutrients-06-01809-f002: Specificity of anti-SVCT2 in Western blot. (A) Specificity of anti-SVCT2 without pre-absorption of antibody with blocking peptide in guinea pig (Gp) brain lysates (HP, BFC, and BC, respectively) seen as a doublet above 60 kDa and in mouse (M) brain lysates as a single band at 60 kDa; (B) Show brain lysates of Gp and M with pre-absorption of antibody with blocking peptide. Block arrow show the non-specific band detected in western blots in a few guinea pig brain lysates. Western blot standard ladder (Std) and band lengths are displayed for both blots.
Mentions: The PCR analysis of SVCT2 expression from HP displayed a tendency to increase in DEF animals, but this was not significant (Figure 1A). No significant differences were observed in either BC or BFC regions between the three groups (Figure 1B,C). Western blot was performed to investigate if VitC deficiency affected SVCT2 protein levels from the three brain regions. Samples resulted in a doublet that may correspond to glycosylated and non-glycosylated forms (bands above 60 kDa and ~70 kDa) (Figure 2A), as has been previously reported [32,33]. Incubation with antibody specific blocking peptide successfully prevented both bands (Figure 2B), confirming specificity of the SVCT2 antibody in both guinea pig and mouse (positive control) lysates (Figure 2A,B). A few brain lysates gave rise to an additional 80 kDa band following anti-SVCT2 blots. This was detected even after pre-absorption with blocking peptide, confirming it to be a non-specific band (Figure 2B). Although we did not quantify band density between the three regions of the brain, hippocampus samples generally appeared to display intense bands compared to the samples from the other two brain regions with the faintest bands pertaining to samples from BFC. No significant changes in protein expression were found between the three dietary groups within the measured brain regions (Figure 3) suggesting that SVCT2 expression is not induced by the dietary regimes applied in this study.

Bottom Line: Biochemical analyses demonstrated significantly decreased total VitC and an increased percentage of dehydroascorbic acid, as well as increased lipid oxidation (malondialdehyde), in the brains of VitC deficient animals (p < 0.0001) compared to controls.No significant changes were detected in either gene or protein expression of SVCT2 between groups or brain regions.In conclusion, chronic pre-and postnatal VitC deficiency increased brain redox imbalance but did not increase SVCT2 expression.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C 1870, Denmark. maypa@sund.ku.dk.

ABSTRACT
Vitamin C (VitC) has several roles in the brain acting both as a specific and non-specific antioxidant. The brain upholds a very high VitC concentration and is able to preferentially retain VitC even during deficiency. The accumulation of brain VitC levels much higher than in blood is primarily achieved by the sodium dependent VitC transporter (SVCT2). This study investigated the effects of chronic pre-and postnatal VitC deficiency as well as the effects of postnatal VitC repletion, on brain SVCT2 expression and markers of oxidative stress in young guinea pigs. Biochemical analyses demonstrated significantly decreased total VitC and an increased percentage of dehydroascorbic acid, as well as increased lipid oxidation (malondialdehyde), in the brains of VitC deficient animals (p < 0.0001) compared to controls. VitC repleted animals were not significantly different from controls. No significant changes were detected in either gene or protein expression of SVCT2 between groups or brain regions. In conclusion, chronic pre-and postnatal VitC deficiency increased brain redox imbalance but did not increase SVCT2 expression. Our findings show potential implications for VitC deficiency induced negative effects of redox imbalance in the brain and provide novel insight to the regulation of VitC in the brain during deficiency.

Show MeSH
Related in: MedlinePlus