Analysis of long-term gene expression in neurons of the hippocampal subfields following traumatic brain injury in rats

M. Shimamura, J. M. Garcia, Donald Prough, Douglas Dewitt, T. Uchida, S. A. Shah, M. A A Avila, Helen Hellmich

Research output: Contribution to journalArticle

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Abstract

After experimental traumatic brain injury (TBI), widespread neuronal loss is progressive and continues in selectively vulnerable brain regions, such as the hippocampus, for months to years after the initial insult. To clarify the molecular mechanisms underlying secondary or delayed cell death in hippocampal neurons after TBI, we compared long-term changes in gene expression in the CA1, CA3 and dentate gyrus (DG) subfields of the rat hippocampus at 24 h and 3, 6, and 12 months after TBI with changes in gene expression in sham-operated rats. We used laser capture microdissection to collect several hundred hippocampal neurons from the CA1, CA3, and DG subfields and linearly amplified the nanogram samples of neuronal RNA with T7 RNA polymerase. Subsequent quantitative analysis of gene expression using ribonuclease protection assay revealed that mRNA expression of the anti-apoptotic gene, Bcl-2, and the chaperone heat shock protein 70 was significantly downregulated at 3, 6 (Bcl-2 only), and 12 months after TBI. Interestingly, the expression of the pro-apoptotic genes caspase-3 and caspase-9 was also significantly decreased at 3, 6 (caspase-9 only), and 12 months after TBI, suggesting that long-term neuronal loss after TBI is not mediated by increased expression of pro-apoptotic genes. The expression of two aging-related genes, p21 and integrin β3 (ITβ3), transiently increased 24 h after TBI, returned to baseline levels at 3 months and significantly decreased below sham levels at 12 months (ITβ3 only). Expression of the gene for the antioxidant glutathione peroxidase-1 also significantly increased 6 months after TBI. These results suggest that decreased levels of neuroprotective genes may contribute to long-term neurodegeneration in animals and human patients after TBI. Conversely, long-term increases in antioxidant gene expression after TBI may be an endogenous neuroprotective response that compensates for the decrease in expression of other neuroprotective genes.

Original languageEnglish (US)
Pages (from-to)87-97
Number of pages11
JournalNeuroscience
Volume131
Issue number1
DOIs
StatePublished - 2005

Fingerprint

Gene Expression
Neurons
Caspase 9
Genes
Dentate Gyrus
Integrins
Hippocampus
Antioxidants
Caspase 12
Traumatic Brain Injury
Laser Capture Microdissection
bcl-2 Genes
HSP70 Heat-Shock Proteins
Ribonucleases
Caspase 3
Cell Death
Down-Regulation
RNA
Messenger RNA
Brain

Keywords

  • antioxidant gene expression
  • apoptotic gene expression
  • laser capture microdissection
  • linear mRNA amplification
  • neurodegeneration
  • neuroprotective gene expression

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Analysis of long-term gene expression in neurons of the hippocampal subfields following traumatic brain injury in rats. / Shimamura, M.; Garcia, J. M.; Prough, Donald; Dewitt, Douglas; Uchida, T.; Shah, S. A.; Avila, M. A A; Hellmich, Helen.

In: Neuroscience, Vol. 131, No. 1, 2005, p. 87-97.

Research output: Contribution to journalArticle

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