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Chronic cerebral hypoperfusion-induced neuropathological changes in rats
M Nanri1, H Miyake, Y Murakami
1Section of Pharmacology Biological Research Lab., Taiho Pharmaceutical Co., Ltd., Tokushima, Japan.
Abstract:
We investigated the time courses of histopathological changes in various brain regions following permanent occlusion of the bilateral common carotid arteries (2VO) in rats. 2VO rats exhibited rarefaction in the white matter, shrinkage of neurons in the cerebral cortex and hippocampus CA1-3 and dentate gyrus areas 1-3 days after the operation. These histological changes in the cortex and hippocampus were accompanied by a decrease in immunoreactivity for microtubule-associated protein 2 (MAP2), a marker protein of neuronal dendrites. Immunoreactivity for glial fibrillary acid protein (GFAP) was observed at 3-7 days after the 2VO operation. A marked increase in GFAP staining of the astrocytes in the cerebral cortex and hippocampus was found 30 days after ligation. Eight-arm radial maze performance was tested from 14 days to 60 days after the operation. The 2VO rats showed fewer initial correct responses than sham-operated control rats during a repeated training period. These findings suggested that the loss in dendritic MAP2 immunoreactivity and an increase in astroglial staining and/or rarefaction of the white matter may cause neuronal death, infarction and learning impairment under conditions of chronic hypoperfusion.
Insights
Chronic hypoperfusion from bilateral common carotid artery occlusion in rats causes white matter rarefaction and neuronal shrinkage. These changes lead to learning impairment, suggesting potential therapeutic targets for stroke.
Area of Science:
- Neuroscience
- Pathology
- Cerebrovascular Research
Background:
- Chronic hypoperfusion is a risk factor for cerebrovascular diseases.
- Understanding the histopathological consequences of reduced blood flow is crucial for developing treatments.
Purpose of the Study:
- To investigate the temporal progression of brain damage after permanent bilateral common carotid artery occlusion (2VO) in rats.
- To correlate histopathological changes with cognitive deficits.
Main Methods:
- Induction of 2VO in rats.
- Histopathological analysis of brain tissue (white matter, cerebral cortex, hippocampus).
- Immunohistochemical staining for MAP2 and GFAP.
- Behavioral testing using an eight-arm radial maze.
Main Results:
- 2VO rats showed white matter rarefaction and neuronal shrinkage within 1-3 days.
- Decreased MAP2 immunoreactivity (neuronal dendrites) and increased GFAP staining (astrocytes) were observed.
- Impaired performance in the radial maze task was evident from 14 to 60 days post-operation.
Conclusions:
- Loss of dendritic markers and increased glial response correlate with neuronal damage and cognitive deficits.
- These findings highlight the impact of chronic hypoperfusion on brain structure and function.
- The study provides insights into the pathophysiology of learning impairment in hypoperfusion models.