Effects of KRG Extract on Excitotoxic Neuronal Cell Damage
KRG Extract Inhibits Glutamate- or NMDA-Induced Excitotoxicity and ROS Generation
As reported previously, primary cultured rat cortical cells are vulnerable to glutamate- or NMDA-induced excitotoxicity.23–25) In this study, we confirmed these findings using the MTT reduction assay, showing that the viability of the cultured cortical cells was reduced by approximately 30–40% as compared to the control cells upon exposure to either L-glutamate or NMDA (Figs. 2A, B). To evaluate the protective effect of KRG extract on the glutamate- or NMDA-induced excitotoxic cell damage, the cultured cells were simultaneously treated with various concentrations of KRG extract. KRG extract provided a marked protection against the excitotoxic damage induced by the two excitatory amino acids (Figs. 2A, B). At the concentration of 3 mg/mL, KRG extract almost completely rescued the cells from the excitotoxic injury, exhibiting the cell viability similar to control cells. We also assessed the effect of memantine on the excitotoxic injury for reference in this study. The protective effects of KRG extract at 3 mg/mL were even more pronounced than that of memantine (Figs. 2A, B).