Induction of EGR1/NGFI-A gene expression by spreading depression and focal cerebral ischemia

Wei Hua Lee, Carolyn Bondy

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

In situ hybridization was used to evaluate EGR1 (NGFI-A) gene expression in the rat brain following focal ischemia caused by middle cerebral artery occlusion (MCAO). At 1 h postlesion (PL), there was a striking increase in EGR1 mRNA in neurons throughout the ipsilateral cortex, with a lesser increase occurring in a patchy distribution in the contralateral cortex. The ipsilateral hemispheric reaction was maximal at 1 h PL, slightly reduced after 3 and 5 h, and resolved after 24 h. Sham surgery limited to meningeal disruption resulted in a similar though less intense induction of EGR1 gene expression in the ipsilateral cortex only. After MCAO but not sham surgery, there was a vivid induction of EGR1 mRNA in the ipsilateral hippocampal formation (CA3 > CA1 > DG). While the hemispheric cortical and hippocampal increases in EGR1 expression had normalized at 24 h PL, intense EGR1 gene expression was seen in neurons of the infarct rim for several days. EGH1 mRNA was also increased in reactive glial cells in the infarct zone from 1 to 9 days after the infarct. In summary, successive waves of transient EGR1 gene expression mark the brain’s response to ischemic injury: these include the widespread, unilateral cortical induction associated with the phenomenon of spreading depression, an apparent transsynaptic activation of contralateral cortex and ipsilateral hippocampal formation - and more sustained responses in injured but surviving neurons and reactive glial cells. The extensive EGRl expression demonstrated in this experimental paradigm suggests that EGR1 is a fundamental component of neural cell activation.

Original languageEnglish (US)
Pages (from-to)225-230
Number of pages6
JournalMolecular and Cellular Neuroscience
Volume4
Issue number3
DOIs
StatePublished - Apr 1 1993

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience
  • Cell Biology

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