Neurotoxicity Research

, Volume 7, Issue 1, pp 143–149

Regulation of glutamate transporters in astrocytes: Evidence for a relationship between transporter expression and astrocytic phenotype

  • Chrissandra J. Zagami
  • Ross D. O’shea
  • Chew L. Lau
  • Surindar S. Cheema
  • Philip M. Beart
Article

DOI: 10.1007/BF03033783

Cite this article as:
Zagami, C.J., O’shea, R.D., Lau, C.L. et al. neurotox res (2005) 7: 143. doi:10.1007/BF03033783

Abstract

The astrocytic glutamate transporters, EAAT1 and EAAT2, remove released L-glutamate from the synaptic milieu thereby maintaining normal excitatory transmission. EAAT dysfunction during the excitotoxicity and oxidative stress of neurological insults may involve homoeostatic mechanisms associated with astrocytic function. We investigated aspects of EAAT function and expression in concert with astrocytic phenotype in primary cultures of cortical astrocytes and mixed cells of the spinal cord. In spinal cord mixed cultures, hydrogen peroxide (300 µM) reduced both EAAT activity and cellular viability to half of their basal values at 24 h post-treatment, but at 2 h EAAT activity was unaltered, while cellular viability was significantly decreased, suggestive of a mechanism for the maintenance of EAAT activity. Cytochemistry for MAP2, GFAP and propidium iodide revealed that neurons and astrocytes were damaged in a time-dependent manner. A change in astrocyte morphology was observed, with astrocyte cell bodies becoming larger and processes becoming more stellate and often shorter in length. EAAT1 immunoreactivity was reduced at 24 h post-treatment and a re-distribution of the protein was noted after 2 h treatment. In pure astrocytes, lipopolysaccharide (1 µg/ml, 3 d) increased [3H]D-aspartate uptake by 90%, as well as EAAT1 immunoreactivity and astrocyte stellation, as shown by immunofluorescent labelling for GFAP. In both culture systems, prominent changes were noted in EAAT function and localization in conjunction with altered astrocytic phenotype. Our findings are indicative of a relationship between astrocytic phenotype and the level of EAAT activity that may be a vital component of astrocytic homeostatic responses in brain injury.

Keywords

Glutamate TrsnsporterAstrocytesEAATGFAPBrain injury

Copyright information

© Springer 2005

Authors and Affiliations

  • Chrissandra J. Zagami
    • 1
    • 2
  • Ross D. O’shea
    • 1
  • Chew L. Lau
    • 1
    • 2
  • Surindar S. Cheema
    • 1
  • Philip M. Beart
    • 1
  1. 1.Brain Injury and Repair Program, Howard Florey InstituteUniversity of MelbourneParkvilleAustralia
  2. 2.Department of PharmacologyUniversity of MelbourneParkvilleAustralia