NEUROPROTECTIVE EFFECTS OF YOKUKANSAN, A TRADITIONAL JAPANESE MEDICINE, ON GLUTAMATE-MEDIATED EXCITOTOXICITY IN CULTURED CELLS

作者：Kawakami Z^*; Kanno H; Ueki T; Terawaki K; Tabuchi M; Ikarashi Y; Kase Y

来源：Neuroscience, 2009, 159(4): 1397-1407.

DOI：10.1016/j.neuroscience.2009.02.004

• astrocytes
• GLAST
• GLT-1
• mRNAs
• NMDA
• PC12

To clarify the mechanism of yokukansan (TJ-54), a traditional Japanese medicine, against glutamate-mediated excitotoxicity, the effects of TJ-54 on glutamate uptake function were first examined using cultured rat cortical astrocytes. Under thiamine-deficient conditions, the uptake of glutamate into astrocytes, and the levels of proteins and mRNA expressions of glutamate aspartate transporter of astrocytes significantly decreased. These decreases were ameliorated in a dose-dependent manner by treatment with TJ-54 (100700 mu g/ml). The improvement of glutamate uptake with TJ-54 was completely blocked by the glutamate transporter inhibitor DL-threo-beta-hydroxyaspartic acid. Effects of TJ-54 on glutamate-induced neuronal death were next examined by using cultured PC12 cells as a model for neurons. Addition of 17.5 mM glutamate to the culture medium induced an approximately 50% cell death, as evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. TJ-54 (1-1000 mu g/ml) inhibited the cell death in a dose-dependent manner. Furthermore, competitive binding assays to glutamate receptors showed that TJ-54 bound potently to N-methyl-D-aspartate receptors, in particular, to its glutamate and glycine recognition sites. These results suggest that TJ-54 may exert a neuroprotective effect against glutamate-induced excitotoxicity not only by amelioration of dysfunction of astrocytes but also by direct protection of neuronal cells.

• 出版日期2009-4-10