Glutamate transporter function of rat hippocampal astrocytes is impaired following the global ischemia

Tu Hsueh Yeh, Hwa Min Hwang, Jin Jung Chen, Tony S. Wu, Allen H. Li, Hung Li Wang*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

75 Scopus citations

Abstract

Astroglial glutamate transporters, GLT-1 and GLAST, play an essential role in removing released glutamate from the extracellular space and are essential for maintaining a low concentration of extracellular glutamate in the brain. It was hypothesized that impaired function of glial glutamate transporters induced by transient global ischemia may lead to an elevated level of extracellular glutamate and subsequent excitotoxic neuronal death. To test this hypothesis, in the present study, we performed whole-cell patch-clamp recording of hippocampal CA1 astrocytes in control or postischemic slices, and measured glutamate transporter activity by recording glutamate-evoked transporter currents. Six to 24 h after global ischemia, maximal amplitude of glutamate transporter currents recorded from postischemic CA1 astrocytes was significantly reduced. Western blotting analysis indicated that transient global ischemia decreased the protein level of GLT-1 in the hippocampal CA1 area without affecting GLAST protein level. Further real-time quantitative RT-PCR assays showed that global ischemia resulted in a decrease in GLT-1 mRNA level of hippocampal CA1 region. Global ischemia-induced reduction in GLT-1 expression and glutamate transporter function of CA1 astrocytes precedes the initiation of delayed neuronal death in CA1 pyramidal layer. The present study provides the evidence that transient global ischemia downregulates glutamate transporter function of hippocampal CA1 astrocytes by decreasing mRNA and protein levels of GLT-1.

Original languageEnglish
Pages (from-to)476-483
Number of pages8
JournalNeurobiology of Disease
Volume18
Issue number3
DOIs
StatePublished - 04 2005

Keywords

  • CA1 astrocyte
  • GLAST transporter
  • GLT1 transporter
  • Glutamate transporter
  • Ischemia
  • Transporter current

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