Kainic Acid and MPP+ Induce Upregulation of GLT-1 in Neuroblastoma and Glia Cells

Abstract

Objective:Glutamate is the major excitatory transmitter in the brain. The excessive glutamate will lead to excitotoxicity. Glutamate transporter-1 (GLT-1) is the major transporter that performs 95% of the glutamate clearance contributing to normal neuronal function and preventing excitotoxicity. In this study, we investigated the effect of two toxins, kainic acid and MPP+ (1-methyl-4- phenylpyridinium), on GLT-1 expression and excitotoxicity in neuroblastoma and glia cells (immortalized human astrocytes).Methods:We treated neuroblastoma and glia cells with kainic acid and MPP+, applied MTT assay to measure the cell viability. We identified the mRNA and protein levels of GLT-1 and also analyzed released glutamate levels using glutamate assay.Results:The mRNA level of GLT-1 increased in neuroblastoma cells as a result of kainic acid or MPP+ treatment while the protein expression of GLT-1 increased in glia cells after the treatment with MPP+. Excess glutamate was found to be decreased after 12 h MPP+ treatment. However, this decrease was no more prominent with further MPP+ treatment.Conclusion:Our results show that GLT-1 levels are elevated as a result of kainic acid or MPP+ treatment as a survival mechanism to prevent excitotoxicity.

Keywords

• excitotoxicity
• glt-1
• glutamate
• mpp+
• kainic acid
• mrna