Pre-conditioning induces the precocious differentiation of neonatal astrocytes to enhance their neuroprotective properties

Ellora Sen, Anirban Basu, Lisa B. Willing, Tracy F. Uliasz, Jaimie L. Myrkalo, Susan J. Vannucci, Sandra J. Hewett, Steven W. Levison

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Hypoxic preconditioning reprogrammes the brain's response to subsequent H/I (hypoxia-ischaemia) injury by enhancing neuroprotective mechanisms. Given that astrocytes normally support neuronal survival and function, the purpose of the present study was to test the hypothesis that a hypoxic preconditioning stimulus would activate an adaptive astrocytic response. We analysed several functional parameters 24 h after exposing rat pups to 3 h of systemic hypoxia (8% O2). Hypoxia increased neocortical astrocyte maturation as evidenced by the loss of GFAP (glial fibrillary acidic protein)- positive cells with radial morphologies and the acquisition of multipolar GFAP-positive cells. Interestingly, many of these astrocytes had nuclear S100B. Accompanying their differentiation, there was increased expression of GFAP, GS (glutamine synthetase), EAAT-1 (excitatory amino acid transporter-1; also known as GLAST), MCT-1 (monocarboxylate transporter-1) and ceruloplasmin. A subsequent H/I insult did not result in any further astrocyte activation. Some responses were cell autonomous, as levels of GS and MCT-1 increased subsequent to hypoxia in cultured forebrain astrocytes. In contrast, the expression of GFAP, GLAST and ceruloplasmin remained unaltered. Additional experiments utilized astrocytes exposed to exogenous dbcAMP (dibutyrylcAMP), which mimicked several aspects of the preconditioning response, to determine whether activated astrocytes could protect neurons from subsequent excitotoxic injury. dbcAMP treatment increased GS and glutamate transporter expression and function, and as hypothesized, protected neurons from glutamate excitotoxicity. Taken altogether, these results indicate that a preconditioning stimulus causes the precocious differentiation of astrocytes and increases the acquisition of multiple astrocytic functions that will contribute to the neuroprotection conferred by a sublethal preconditioning stress.

Original languageEnglish (US)
Article numbere00062
Pages (from-to)159-170
Number of pages12
JournalASN Neuro
Volume3
Issue number3
DOIs
StatePublished - Sep 26 2011
Externally publishedYes

Keywords

  • Cell death
  • Excitotoxicity
  • Glutamate
  • Glutamine synthetase
  • Stroke
  • Transporter

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology

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  • Cite this

    Sen, E., Basu, A., Willing, L. B., Uliasz, T. F., Myrkalo, J. L., Vannucci, S. J., Hewett, S. J., & Levison, S. W. (2011). Pre-conditioning induces the precocious differentiation of neonatal astrocytes to enhance their neuroprotective properties. ASN Neuro, 3(3), 159-170. [e00062]. https://doi.org/10.1042/AN20100029