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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

Western blot analysis of SVCT2 protein in brain. Densitometry analysis of western blot analysis of SVCT2 protein levels from three brain regions of guinea pigs HP (A); BC (B) and BFC (C); CTRL: control group, REPL: repleted group and DEF: deficient group. Representative pictures of the blots are depicted above each bar graph. Values are displayed as mean of normalized ratio to actin ± SD, the exact SVCT2 densitometry mean values (±SD) are provided in Table 3.
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nutrients-06-01809-f003: Western blot analysis of SVCT2 protein in brain. Densitometry analysis of western blot analysis of SVCT2 protein levels from three brain regions of guinea pigs HP (A); BC (B) and BFC (C); CTRL: control group, REPL: repleted group and DEF: deficient group. Representative pictures of the blots are depicted above each bar graph. Values are displayed as mean of normalized ratio to actin ± SD, the exact SVCT2 densitometry mean values (±SD) are provided in Table 3.

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)

Western blot analysis of SVCT2 protein in brain. Densitometry analysis of western blot analysis of SVCT2 protein levels from three brain regions of guinea pigs HP (A); BC (B) and BFC (C); CTRL: control group, REPL: repleted group and DEF: deficient group. Representative pictures of the blots are depicted above each bar graph. Values are displayed as mean of normalized ratio to actin ± SD, the exact SVCT2 densitometry mean values (±SD) are provided in Table 3.
© Copyright Policy
Related In: Results  -  Collection

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

nutrients-06-01809-f003: Western blot analysis of SVCT2 protein in brain. Densitometry analysis of western blot analysis of SVCT2 protein levels from three brain regions of guinea pigs HP (A); BC (B) and BFC (C); CTRL: control group, REPL: repleted group and DEF: deficient group. Representative pictures of the blots are depicted above each bar graph. Values are displayed as mean of normalized ratio to actin ± SD, the exact SVCT2 densitometry mean values (±SD) are provided in Table 3.
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