Grape seed proanthocyanidin extract inhibits glutamate-induced cell death through inhibition of calcium signals and nitric oxide formation in cultured rat hippocampal neurons

Abstract

BackgroundProanthocyanidin is a polyphenolic bioflavonoid with known antioxidant activity. Some flavonoids have a modulatory effect on [Ca2+]i. Although proanthocyanidin extract from blueberries reportedly affects Ca2+ buffering capacity, there are no reports on the effects of proanthocyanidin on glutamate-induced [Ca2+]i or cell death. In the present study, the effects of grape seed proanthocyanidin extract (GSPE) on glutamate-induced excitotoxicity was investigated through calcium signals and nitric oxide (NO) in cultured rat hippocampal neurons.ResultsPretreatment with GSPE (0.3-10 μg/ml) for 5 min inhibited the [Ca2+]i increase normally induced by treatment with glutamate (100 μM) for 1 min, in a concentration-dependent manner. Pretreatment with GSPE (6 μg/ml) for 5 min significantly decreased the [Ca2+]i increase normally induced by two ionotropic glutamate receptor agonists, N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). GSPE further decreased AMPA-induced response in the presence of 1 μM nimodipine. However, GSPE did not affect the 50 mM K+-induced increase in [Ca2+]i. GSPE significantly decreased the metabotropic glutamate receptor agonist (RS)-3,5-Dihydroxyphenylglycine-induced increase in [Ca2+]i, but it did not affect caffeine-induced response. GSPE (0.3-6 μg/ml) significantly inhibited synaptically induced [Ca2+]i spikes by 0.1 mM [Mg2+]o. In addition, pretreatment with GSPE (6 μg/ml) for 5 min inhibited 0.1 mM [Mg2+]o- and glutamate-induced formation of NO. Treatment with GSPE (6 μg/ml) significantly inhibited 0.1 mM [Mg2+]o- and oxygen glucose deprivation-induced neuronal cell death.ConclusionsAll these data suggest that GSPE inhibits 0.1 mM [Mg2+]o- and oxygen glucose deprivation-induced neurotoxicity through inhibition of calcium signals and NO formation in cultured rat hippocampal neurons.

Cyanidin-3-glucoside inhibits glutamate-induced Zn2+ signaling and neuronal cell death in cultured rat hippocampal neurons by inhibiting Ca2+-induced mitochondrial depolarization and formation of reactive oxygen species

“…These results are indirectly supported by the report that C3G inhibits agonistinduced calcium signaling in PC12 cells (Shazia et al, 2014). Since flavonoids have been reported to inhibit agonist-induced Ca 2þ signals (Ahn et al, 2011;Bae et al, 2002;Han et al, 2008;Saponara et al, 2002;Shah et al, 1999;Shazia et al, 2014), flavonoids including C3G can inhibit agonist-induced [Zn 2þ ] i increase.…”

“…Polyphenols have antioxidant effects, anti-inflammatory activity, anti-carcinogenic effects, cardiovascular protective effects and antiaging effects (Han et al, 2007). Flavonoids, the largest group of polyphenols, have been reported to inhibit Ca 2þ channels and agonist-induced intracellular free Ca 2þ concentration ([Ca 2þ ] i ) increase (Ahn et al, 2011;Bae et al, 2002;Saponara et al, 2002;Shah et al, 1999). Cyanidin-3-glucoside (C3G) is a component of anthocyanin which belongs to the flavonoid family.…”

Methodologies and limitations in the analysis of potential neuroprotective compounds derived from natural products

“…In these approaches, compounds are added to brain derived cells and challenged with toxic substances known to produce cell damage and death, such as glutamate or hydrogen peroxide, which will generate excessive ROS and/or RNS [12,13]. This approach can include immortalized cell lines [14], or primary cells, which are generally derived from embryonic or neonatal brains of mice or rats [15,16].…”

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“…Extensive investigations have been undertaken to determine the neuroprotective effects of wine polyphenols [6,7,8] Several neuroprotective mechanisms of action have been proposed, suggesting that polyphenols exert their activities by reducing the production and the accumulation of Reactive oxygen species (ROS), whose accumulation is likely to play a crucial pathological role in brain aging, reducing oxidative stress and inflammation and modulating the activity of intracellular signal transduction molecules. There is evidence that polyphenols found in grape seed extract affects the metabotropic glutamate receptor agonist response in group I mGlu receptors [9]. In the present research, we aim to study the novel drug target for Parkinson's disease: (1) to predict the structural model of mGluR4, (2) to perform virtual screening and docking to identify agonist molecules from wine polyphenols, and (3) to investigate structural analysis of mGluR4-ligand complex using molecular dynamics simulation studies to study the conformation of the structure.…”