ISSN:
1437-1596
Keywords:
Key words Traumatic head injury
;
Diffuse axonal ¶injury
;
Tumor necrosis factor-α
;
β-Amyloid precursor ¶protein
;
Fluid percussion device
;
Glial cell
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
,
Law
Notes:
Abstract The immunolocalization of tumor necrosis factor-α (TNFα) after diffuse axonal injury (DAI) is demonstrated using a midline fluid percussion rat model (moderate brain injury of 1000 mm Hg was generated) and the effects of TNFα on the axolemmal permeability using horseradish peroxidase as a tracer. In addition, the accumulation of β-amyloid precursor protein (β-APP) was investigated, which has recently been shown to be a reliable marker for the diagnosis of DAI in cases with fatal head injury. TNFα levels in brain tissues from the impact site and the cortex including the corpus callosum, gradually increased during the first 1 h, rose to a maximal elevation at 3 h, gradually decreased at 6 h and decreased further at 24 h. Horseradish peroxidase (HRP) tracer experiments revealed that primary axonal damage appeared as early as 15 min after impact but rapidly recovered and that 1 h after impact, secondary axonal damage occurred in the corpus callosum and the brain stem. By immunoelectron microscopy it was seen that β-APP accumulated in the axon from 1 h after impact demonstrating that there was functional axonal damage. TNFα reactions were detected in the lysosomes of microglia 30 min after impact and 1 h after impact these reactions were mainly detected in the glial cells (such as microglia, astrocytes and oligodendrocytes) in the corpus callosum and the brain stem. It is generally accepted that TNFα directly induces primary demyelination and oligodendrocyte apoptosis. Therefore, TNFα conveyed from the microglial cells is one cofactor contributing to the formation of the delayed axonal damage observed at these sites. The present study suggests that TNFα conveyed from the glial cells may contribute to the pathogenic mechanism of DAI formation following fluid percussive brain injury.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004149900095
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