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Differential neuroprotective activity of two different grape seed extracts.

Narita K, Hisamoto M, Okuda T, Takeda S - PLoS ONE (2011)

Bottom Line: By contrast, Muscat Bailey A, a red, hybrid variety (Muscat Humburg × Bailey), failed to show any neuroprotective effect.Unlike brain-derived neurotrophic factor and other neuroprotective cytokines, Koshu extract did not induce Akt phosphorylation.These data suggest the presence of high affinity molecular targets for polyphenols in hippocampal neurons, which induce neuroprotective effects in a manner different from BDNF, and the importance of low molecular weight polyphenols and/or procyanidin oligomers for neuroprotection.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, Interdisciplinary Graduate School of Medicine & Engineering, University of Yamanashi, Yamanashi, Japan.

ABSTRACT
Glutamate excitotoxicity is one of the major events that takes place during various neurotoxic injuries such as brain ischemia. We prepared grape seed extracts, from two different varieties, containing high amounts of polyphenols but little resveratrol. Their neuroprotective effects were investigated using primary culture of neonatal mouse hippocampal neurons treated with an excitotoxic concentration of glutamate. Koshu, a white, local variety of V. vinifera, alleviated the acute inactivation of Erk1/2 and dendrite retraction in cultured hippocampal neurons exposed to a toxic concentration of glutamate (1.0 ng/ml). By contrast, Muscat Bailey A, a red, hybrid variety (Muscat Humburg × Bailey), failed to show any neuroprotective effect. Unlike brain-derived neurotrophic factor and other neuroprotective cytokines, Koshu extract did not induce Akt phosphorylation. Koshu extract also augmented neuron survival rate 24 hours after glutamate toxicity. The comparison of polyphenols between the two samples by liquid chromatography/time-of-flight mass spectrometry demonstrated that Koshu had higher amounts of low molecular weight polyphenols along with several Koshu-specific procyanidin oligomers. These data suggest the presence of high affinity molecular targets for polyphenols in hippocampal neurons, which induce neuroprotective effects in a manner different from BDNF, and the importance of low molecular weight polyphenols and/or procyanidin oligomers for neuroprotection.

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Koshu GSE protects dendrite processing of cultured hippocampal neurons exposed to a toxic concentration of glutamate.(A) Representative image of untreated hippocampal neurons at 8 DIV immunostained for MAP2. Bar, 100 µm. (B) Representative binary images of cultured hippocampal neurons immunostained for MAP2 with no treatment or after a 30 min treatment with 50 µM glutamate alone, 50 µM glutamate plus 1.0 ng/ml KOS, or 50 µM glutamate plus 1.0 ng/ml MBA. Bar, 100 µm. (C) Quantification of the mean dendrite length by morphometric analysis (n = 10). ***, P<0.001 versus untreated controls.
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pone-0014575-g002: Koshu GSE protects dendrite processing of cultured hippocampal neurons exposed to a toxic concentration of glutamate.(A) Representative image of untreated hippocampal neurons at 8 DIV immunostained for MAP2. Bar, 100 µm. (B) Representative binary images of cultured hippocampal neurons immunostained for MAP2 with no treatment or after a 30 min treatment with 50 µM glutamate alone, 50 µM glutamate plus 1.0 ng/ml KOS, or 50 µM glutamate plus 1.0 ng/ml MBA. Bar, 100 µm. (C) Quantification of the mean dendrite length by morphometric analysis (n = 10). ***, P<0.001 versus untreated controls.

Mentions: Next, we validated the protective effect of GSEs based on neuronal morphology. Under normal conditions, cultured hippocampal neurons at 8 days in vitro (DIV) extend long, highly branched dendrites and are heavily connected to each other, as demonstrated by immunostaining for microtubule-associated protein 2 (MAP2) (Figure 2A and B). However, when neurons were treated with glutamate for 30 min, stressed neurons exhibited morphological changes. The deleterious effects of glutamate on neuronal morphology were recognized as low as 10–20 µM, in which some MAP2-positive dendrites showed an irregular punctate staining, indicative of neuronal damage (data not shown). When neurons were exposed to 50 µM glutamate, the length and branching of dendrites in neural networks were severely reduced (Figure 2B). A morphometric analysis indicated that the mean dendrite length of stressed neurons was reduced by 50% as compared to the untreated control (Figure 2C). When cells were treated with 50 µM glutamate in the presence of 1.0 ng/ml KOS GSE, the dendritic network connecting distant neurons, as well as the number of branches appeared to be better preserved compared to cells treated with glutamate alone (Figure 2B). Treatment with KOS GSE also alleviated the reduction in mean dendrite length significantly (Figure 2C). On the other hand, 1.0 ng/ml MBA GSE did not show any protective effect on dendrite arborization during glutamate excitotoxicity, which was consistent with the Erk1/2 phosphorylation data. These data indicated that KOS, but not MBA GSE, protected dendritic arborization of hippocampal neurons exposed to excitotoxic concentrations of glutamate.


Differential neuroprotective activity of two different grape seed extracts.

Narita K, Hisamoto M, Okuda T, Takeda S - PLoS ONE (2011)

Koshu GSE protects dendrite processing of cultured hippocampal neurons exposed to a toxic concentration of glutamate.(A) Representative image of untreated hippocampal neurons at 8 DIV immunostained for MAP2. Bar, 100 µm. (B) Representative binary images of cultured hippocampal neurons immunostained for MAP2 with no treatment or after a 30 min treatment with 50 µM glutamate alone, 50 µM glutamate plus 1.0 ng/ml KOS, or 50 µM glutamate plus 1.0 ng/ml MBA. Bar, 100 µm. (C) Quantification of the mean dendrite length by morphometric analysis (n = 10). ***, P<0.001 versus untreated controls.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3025924&req=5

pone-0014575-g002: Koshu GSE protects dendrite processing of cultured hippocampal neurons exposed to a toxic concentration of glutamate.(A) Representative image of untreated hippocampal neurons at 8 DIV immunostained for MAP2. Bar, 100 µm. (B) Representative binary images of cultured hippocampal neurons immunostained for MAP2 with no treatment or after a 30 min treatment with 50 µM glutamate alone, 50 µM glutamate plus 1.0 ng/ml KOS, or 50 µM glutamate plus 1.0 ng/ml MBA. Bar, 100 µm. (C) Quantification of the mean dendrite length by morphometric analysis (n = 10). ***, P<0.001 versus untreated controls.
Mentions: Next, we validated the protective effect of GSEs based on neuronal morphology. Under normal conditions, cultured hippocampal neurons at 8 days in vitro (DIV) extend long, highly branched dendrites and are heavily connected to each other, as demonstrated by immunostaining for microtubule-associated protein 2 (MAP2) (Figure 2A and B). However, when neurons were treated with glutamate for 30 min, stressed neurons exhibited morphological changes. The deleterious effects of glutamate on neuronal morphology were recognized as low as 10–20 µM, in which some MAP2-positive dendrites showed an irregular punctate staining, indicative of neuronal damage (data not shown). When neurons were exposed to 50 µM glutamate, the length and branching of dendrites in neural networks were severely reduced (Figure 2B). A morphometric analysis indicated that the mean dendrite length of stressed neurons was reduced by 50% as compared to the untreated control (Figure 2C). When cells were treated with 50 µM glutamate in the presence of 1.0 ng/ml KOS GSE, the dendritic network connecting distant neurons, as well as the number of branches appeared to be better preserved compared to cells treated with glutamate alone (Figure 2B). Treatment with KOS GSE also alleviated the reduction in mean dendrite length significantly (Figure 2C). On the other hand, 1.0 ng/ml MBA GSE did not show any protective effect on dendrite arborization during glutamate excitotoxicity, which was consistent with the Erk1/2 phosphorylation data. These data indicated that KOS, but not MBA GSE, protected dendritic arborization of hippocampal neurons exposed to excitotoxic concentrations of glutamate.

Bottom Line: By contrast, Muscat Bailey A, a red, hybrid variety (Muscat Humburg × Bailey), failed to show any neuroprotective effect.Unlike brain-derived neurotrophic factor and other neuroprotective cytokines, Koshu extract did not induce Akt phosphorylation.These data suggest the presence of high affinity molecular targets for polyphenols in hippocampal neurons, which induce neuroprotective effects in a manner different from BDNF, and the importance of low molecular weight polyphenols and/or procyanidin oligomers for neuroprotection.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Cell Biology, Interdisciplinary Graduate School of Medicine & Engineering, University of Yamanashi, Yamanashi, Japan.

ABSTRACT
Glutamate excitotoxicity is one of the major events that takes place during various neurotoxic injuries such as brain ischemia. We prepared grape seed extracts, from two different varieties, containing high amounts of polyphenols but little resveratrol. Their neuroprotective effects were investigated using primary culture of neonatal mouse hippocampal neurons treated with an excitotoxic concentration of glutamate. Koshu, a white, local variety of V. vinifera, alleviated the acute inactivation of Erk1/2 and dendrite retraction in cultured hippocampal neurons exposed to a toxic concentration of glutamate (1.0 ng/ml). By contrast, Muscat Bailey A, a red, hybrid variety (Muscat Humburg × Bailey), failed to show any neuroprotective effect. Unlike brain-derived neurotrophic factor and other neuroprotective cytokines, Koshu extract did not induce Akt phosphorylation. Koshu extract also augmented neuron survival rate 24 hours after glutamate toxicity. The comparison of polyphenols between the two samples by liquid chromatography/time-of-flight mass spectrometry demonstrated that Koshu had higher amounts of low molecular weight polyphenols along with several Koshu-specific procyanidin oligomers. These data suggest the presence of high affinity molecular targets for polyphenols in hippocampal neurons, which induce neuroprotective effects in a manner different from BDNF, and the importance of low molecular weight polyphenols and/or procyanidin oligomers for neuroprotection.

Show MeSH
Related in: MedlinePlus