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Middle cerebral artery thrombosis: acute blood-brain barrier consequences
W D Dietrich1, R Prado, B D Watson
1Department of Neurology, University of Miami School of Medicine, Florida 33101.
Abstract:
The effect of middle cerebral artery (MCA) thrombosis on the integrity of the blood-brain barrier (BBB) was studied in rats using horseradish peroxidase (HRP). Endothelial injury with subsequent platelet thrombosis was produced by means of a rose bengal-sensitized photochemical reaction, facilitated by irradiating the right proximal MCA segment with the focused beam of an argon laser. At 15 minutes following thrombosis formation, diffuse leakage of HRP was observed bilaterally within cortical and subcortical brain areas. Peroxidase extravasation was most dense within the territory of the occluded artery including neocortical areas and dorso-lateral striatum. Contralaterally, a similar distribution was observed but with less intense HRP leakage. Ultrastructural studies demonstrated an increase in permeability to HRP within arterioles, venules and capillaries. At these sites, the vascular endothelium contained HRP-filled pinocytotic vesicles and tubular profiles. Although less intense, bilateral HRP leakage was also observed following MCA stenosis or femoral artery occlusion. Endothelial-platelet interactions at the site of vascular injury may be responsible for releasing substances or neurohumoral factors which contribute to the acute opening of the BBB.
Insights
Middle cerebral artery (MCA) thrombosis acutely disrupts the blood-brain barrier (BBB) in rats, causing widespread leakage. Endothelial injury and platelet interactions may trigger this rapid BBB opening.
Area of Science:
- Neuroscience
- Vascular Biology
- Pathophysiology
Background:
- The blood-brain barrier (BBB) protects the central nervous system but can be compromised during vascular events.
- Middle cerebral artery (MCA) occlusion is a common cause of ischemic stroke, significantly impacting brain function.
Purpose of the Study:
- To investigate the immediate effects of MCA thrombosis on BBB integrity in a rat model.
- To determine the extent and pattern of BBB disruption following MCA occlusion.
Main Methods:
- MCA thrombosis was induced using a rose bengal-sensitized photochemical reaction and argon laser irradiation in rats.
- Horseradish peroxidase (HRP) was used as a tracer to assess BBB permeability.
- Ultrastructural analysis examined endothelial changes at the capillary, arteriole, and venule levels.
Main Results:
- Diffuse HRP leakage was observed bilaterally in cortical and subcortical areas 15 minutes post-thrombosis.
- HRP extravasation was most pronounced within the MCA territory, including neocortical and striatal regions.
- Ultrastructural studies revealed increased endothelial permeability with HRP-filled vesicles in cerebral microvasculature.
Conclusions:
- MCA thrombosis leads to acute, bilateral disruption of the BBB.
- Endothelial injury and platelet aggregation at the site of vascular occlusion may release factors contributing to BBB opening.
- These findings highlight the rapid vascular consequences of MCA thrombosis, relevant to stroke pathophysiology.