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Updated: Aug 10, 2026
Photothrombotic Ischemia: A Minimally Invasive and Reproducible Photochemical Cortical Lesion Model for Mouse Stroke Studies
Published on: June 9, 2013
A Linear Temporal Increase in Thrombin Activity and Loss of Its Receptor in Mouse Brain following Ischemic Stroke
Doron Bushi1,2, Efrat Shavit Stein1, Valery Golderman1,2
1Comprehensive Stroke Center, Department of Neurology, The J. Sagol Neuroscience Center, Chaim Sheba Medical Center, Tel HaShomer, Israel.
Background:
Brain thrombin activity is increased following acute ischemic stroke and may play a pathogenic role through the protease-activated receptor 1 (PAR1). In order to better assess these factors, we obtained a novel detailed temporal and spatial profile of thrombin activity in a mouse model of permanent middle cerebral artery occlusion (pMCAo).
Methods:
Thrombin activity was measured by fluorescence spectroscopy on coronal slices taken from the ipsilateral and contralateral hemispheres 2, 5, and 24 h following pMCAo (n = 5, 6, 5 mice, respectively). Its spatial distribution was determined by punch samples taken from the ischemic core and penumbra and further confirmed using an enzyme histochemistry technique (n = 4). Levels of PAR1 were determined using western blot.
Results:
Two hours following pMCAo, thrombin activity in the stroke core was already significantly higher than the contralateral area (11 ± 5 vs. 2 ± 1 mU/ml). At 5 and 24 h, thrombin activity continued to rise linearly (r = 0.998, p = 0.001) and to expand in the ischemic hemisphere beyond the ischemic core reaching deleterious levels of 271 ± 117 and 123 ± 14 mU/ml (mean ± SEM) in the basal ganglia and ischemic cortex, respectively. The peak elevation of thrombin activity in the ischemic core that was confirmed by fluorescence histochemistry was in good correlation with the infarcts areas. PAR1 levels in the ischemic core decreased as stroke progressed and thrombin activity increased.
Conclusion:
In conclusion, there is a time- and space-related increase in brain thrombin activity in acute ischemic stroke that is closely related to the progression of brain damage. These results may be useful in the development of therapeutic strategies for ischemic stroke that involve the thrombin-PAR1 pathway in order to prevent secondary thrombin related brain damage.
Insights
Brain thrombin activity significantly increases after ischemic stroke, correlating with brain damage progression. Targeting the thrombin-protease-activated receptor 1 (PAR1) pathway may offer new therapeutic strategies for acute ischemic stroke.
Area of Science:
- Neuroscience
- Biochemistry
- Pathology
Background:
- Brain thrombin activity elevates post-ischemic stroke.
- Thrombin may contribute to stroke pathology via protease-activated receptor 1 (PAR1).
Purpose of the Study:
- To profile thrombin activity's temporal and spatial dynamics in a mouse model of permanent middle cerebral artery occlusion (pMCAo).
Main Methods:
- Thrombin activity measured using fluorescence spectroscopy on brain slices at 2, 5, and 24 hours post-pMCAo.
- Spatial distribution assessed via punch samples and enzyme histochemistry.
- Protease-activated receptor 1 (PAR1) levels determined by western blot.
Main Results:
- Thrombin activity was significantly elevated in the stroke core within 2 hours, increasing linearly and expanding spatially over 24 hours.
- Peak thrombin activity correlated with infarct size.
- PAR1 levels decreased in the ischemic core as thrombin activity rose.
Conclusions:
- Brain thrombin activity increases over time and space following acute ischemic stroke, closely linked to brain damage.
- Findings suggest the thrombin-PAR1 pathway as a potential therapeutic target for preventing secondary damage in ischemic stroke.
