DNA array reveals altered gene expression in response to focal cerebral ischemia

133

124

Understanding the role of tumor necrosis factor (TNF) in the life-death balance of ischemically injured neurons demands insight into the cellular synthesis of TNF, especially in the acute phase after induction of ischemia. Here, using approximated stereological methods and quantitative reverse transcription (RT) real-time polymerase chain reaction (PCR) analysis, the cellular synthesis of TNF from 30 mins to 10 days after induction of focal cerebral ischemia in mice was investigated. Reverse transcription real-time PCR analysis showed that TNF mRNA increased 2-to 3-fold within 1 hour after induction of ischemia. A significant 8-fold increase was observed at 4 hours when faintly labelled TNF mRNA-expressing and TNF immunoreactive microglial-like cells were easily identifiable in the peri-infarct and infarct. By 6 hours, TNF synthesizing cells were identified as Mac-1 immunopositive, glial fibrillary acidic protein immunonegative microglia-macrophages. The level of TNF mRNA and the numbers of TNF mRNA-expressing microglia-macrophages peaked at 12 hours, and the number of TNF immunoreactive cells at 24 hours. Neuronal TNF mRNA and TNF protein levels remained at constant, very low, levels. The data suggest that the pathophysiologically important TNF, produced in the acute phase from mins to 6 hours after an ischemic attack in mice, is synthesized by microglia-macrophages.

Section: Discussionmentioning

confidence: 99%

A Quantitative Study of Microglial—Macrophage Synthesis of Tumor Necrosis Factor during Acute and Late Focal Cerebral Ischemia in Mice

Lambertsen

Meldgaard

Ladeby

et al. 2005

133

124

“…However, the majority studies measured gene profiles in the brain cells other than SVZ cells focusing on the acute stage of ischemic stroke (Sharp et al, 2000;Kim et al, 2002;Schmidt-Kastner et al, 2002;Lu et al, 2004;Rickhag et al, 2006). Further studies to identify genes trigged by ischemia specific for neural progenitor cells are warranted.…”

Section: Discussionmentioning

confidence: 99%

Stroke Induces Gene Profile Changes Associated with Neurogenesis and Angiogenesis in Adult Subventricular Zone Progenitor Cells

Liu¹,

Zhang²,

Zhang³

et al. 2006

105

100

Neural progenitor cells in the subventricular zone (SVZ) of the lateral ventricular wall give rise to new neurons throughout rodent life. Ischemic stroke induces angiogenesis and neurogenesis. Using laser capture microdissection (LCM) in combination with microarrays containing approximately 400 known genes associated with stem cells and angiogenesis, we investigated gene profiles of SVZ cells in the adult mouse subjected to middle cerebral artery occlusion. Our data revealed that nonstroke SVZ cells expressed sets of genes that are important for neural progenitor cell proliferation, differentiation, and migration. In addition, stroke SVZ cells expressed many genes involved in neurogenesis during embryonic development but were not detected in nonstroke SVZ cells. Stroke upregulated genes were verified by real-time reverse transcriptase-polymerase chain reaction and immunostaining. These data indicate that adult SVZ cells recapture embryonic molecular signals after stroke and provide insight into the molecular mechanisms, which regulate the biological function of neural progenitor cells in the SVZ of adult rodent brain under physiological and stroke conditions.

“…The reason for not only choosing the periinfarction area was that especially at early time points after HI there is no clearly defined area of infarction, making it impossible to dissect out the periinfarction area. In this study, a moderate hypoxic-ischemic insult was induced, which results in somewhat delayed development of injury over at least 1 or 2 days (Blumberg et al, 1997;Gilland et al, 1998;Nakajima et al, 2000), in contrast to the model of permanent middle cerebral artery occlusion used in other microarray studies (Kim et al, 2002;Lu et al, 2003), where maximal lesion volume is already established 3 or 4 hours after occlusion (Kaplan et al, 1991;Memezawa et al, 1992). In addition, the model of HI involves reperfusion and the studies were performed in neonatal animals.…”

Section: Discussionmentioning

confidence: 99%

“…Several studies have been performed studying changes in gene expression after ischemia in the adult brain using microarrays (Jin et al, 2001;Kim et al, 2002;Lu et al, 2003;Raghavendra Rao et al, 2002;Schmidt-Kastner et al, 2002;Schwarz et al, 2002;Tang et al, 2002), showing many new genes of interest. Many studies have, however, been limited to study the gene expression in a certain region at one specific time point (Kim et al, 2002;Lu et al, 2003;Schmidt-Kastner et al, 2002).…”

mentioning

confidence: 99%

“…Many studies have, however, been limited to study the gene expression in a certain region at one specific time point (Kim et al, 2002;Lu et al, 2003;Schmidt-Kastner et al, 2002). In the setting of the immature brain, gene-expression studies directed at a particular group of genes using in situ hybridization or real-time quantitative reverse-transcription polymerase chain reaction (PCR) have been performed (e.g., Aden et al, 1994;Bona et al, 1999;Gubits et al, 1993;Vannucci et al, 1998).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Global Gene Expression in the Immature Brain after Hypoxia-Ischemia

Hedtjärn¹,

Mallard²,

Eklind

et al. 2004

Summary:Ischemia induces a complex response of differentially expressed genes in the brain. In order to understand the specific mechanisms of injury in the developing brain, it is important to obtain information on global changes in the transcriptome after neonatal hypoxia-ischemia. In this study, oligonucleotide arrays were used to investigate genomic changes at 2, 8, 24, and 72 hours after neonatal hypoxia-ischemia, which was induced in 9-day-old mice by left carotid artery ligation followed by hypoxia (10% O 2 ). In total, 343 genes were differentially expressed in cortex, hippocampus, thalamus, and striatum 2 to 72 hours after hypoxia-ischemia, when comparing ipsilateral with contralateral hemispheres and with controls, using the significance analysis for microarrays. A total of 283 genes were upregulated and 60 were downregulated, and 94% of the genes had not previously been shown after neonatal hypoxia-ischemia. Genes related to transcription factors and metabolism had mostly upregulated transcripts, whereas most downregulated genes belonged to the categories of ion and vesicular transport and signal transduction. Genes involved in transcription, stress, and apoptosis were induced early after the insult, and many new genes that may play important roles in the pathophysiology of neonatal hypoxiaischemia were identified.