The Two Patterns of Reactive Astrocytosis in Postischemic Rat Brain

The distribution and time course of postischemic astrocyte hypertrophy and hyperplasia and the relationship to neuronal viability or necrosis was studied in rats subjected to 30 min of carotid and vertebral artery occlusion followed by reperfusion from 3 h to 5 weeks. Intermediate filaments (IFs) we...

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Bibliographic Details
Published in:Journal of cerebral blood flow and metabolism 1990-11, Vol.10 (6), p.850-859
Main Authors: Petito, Carol K., Morgello, Susan, Felix, Juan C., Lesser, Martin L.
Format: Article
Language:English
Subjects:
Animals
Astrocytes - metabolism
Astrocytes - ultrastructure
Biological and medical sciences
Brain Ischemia - metabolism
Brain Ischemia - pathology
Glial Fibrillary Acidic Protein - metabolism
Immunohistochemistry
Male
Medical sciences
Nervous system involvement in other diseases. Miscellaneous
Neurology
Rats
Rats, Inbred Strains
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Summary:The distribution and time course of postischemic astrocyte hypertrophy and hyperplasia and the relationship to neuronal viability or necrosis was studied in rats subjected to 30 min of carotid and vertebral artery occlusion followed by reperfusion from 3 h to 5 weeks. Intermediate filaments (IFs) were evaluated by electron microscopy, IF proteins by immunohistochemistry, and astrocyte division by [3H]thymidine uptake. Glial fibrillary acidic protein (GFAP) increased in damaged and nondamaged brain regions by 2 days and was associated with cell enlargement, increases in IF, and transformation of GFAP-negative into GFAP-positive glia. Cell hypertrophy and increased GFAP persisted only in regions of neuronal necrosis whereas the number and size of GFAP-positive astrocytes returned to control levels in nondamaged regions by 2 weeks. Astrocyte hyperplasia was not seen until 3 days and was confined to damaged brain regions. Vimentin-positive astrocytes were numerous by 2 days in damaged brain and remained only in those regions at 5 weeks. The data demonstrate that reactive astrocytosis develops in undamaged brain, but is reversible with prolonged survival, whereas reactive astrocytosis that accompanies structural brain damage persists for prolonged periods and is associated with hyperplasia, as well as hypertrophy. In addition, the results show that astrocyte expression of vimentin is more specific than GFAP in identifying regions of permanent ischemic injury during the early postischemic period.
ISSN:0271-678X
1559-7016
DOI:10.1038/jcbfm.1990.141