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Hypoperfusion induces overexpression of beta-amyloid precursor protein mRNA in a focal ischemic rodent model
1Department of Pharmacodynamics and Center for Neurobiology of Aging, University of Florida, Gainesville, FL 32610, USA.
Abstract:
Silent stroke is one of the risk factors of dementia. In the present study, we used a novel focal ischemic animal model to investigate the effects of comparatively small changes of cerebral blood flow (CBF) on the expression of beta-amyloid precursor protein (APP) mRNA. Focal ischemia was achieved by introducing a 4-0 monofilament to the bifurcation of anterior and middle cerebral arteries. Brain samples were harvested from ischemic core and penumbra of cortices at 1, 4 and 7 days following ischemia. The expression of APP mRNA was assessed by RT-PCR. The CBF was decreased to 50% for 1 day after stroke and recovered to 90% at the fourth day after stroke. The changes of CBF were accompanied by an increase in the expression of APP mRNA. APP mRNA increased to 208% and 152% in the penumbra and core ischemic regions, respectively, on the fourth day after MCAO and remained high through the seventh day of ischemia. This study suggests brain hypoperfusion enhances APP mRNA expression and may contribute to the progression of cognitive impairment after silent stroke.
Insights
Silent strokes can increase dementia risk. Reduced cerebral blood flow (CBF) after a stroke significantly elevates beta-amyloid precursor protein (APP) mRNA expression, potentially worsening cognitive decline.
Area of Science:
- Neuroscience
- Cerebrovascular Research
Background:
- Silent stroke is a known risk factor for dementia.
- Understanding the molecular mechanisms linking cerebral hypoperfusion to cognitive impairment is crucial.
Purpose of the Study:
- To investigate the impact of reduced cerebral blood flow (CBF) on beta-amyloid precursor protein (APP) mRNA expression in a novel focal ischemic animal model.
- To explore the relationship between hypoperfusion and cognitive decline following silent stroke.
Main Methods:
- A focal ischemic animal model was created using monofilament occlusion of cerebral arteries.
- Brain samples from ischemic core and penumbra were analyzed for APP mRNA expression using RT-PCR at 1, 4, and 7 days post-ischemia.
- Cerebral blood flow (CBF) was monitored throughout the study period.
Main Results:
- CBF decreased to 50% post-stroke, recovering to 90% by day 4.
- APP mRNA expression significantly increased in both penumbra (208%) and core (152%) regions by day 4, remaining elevated through day 7.
- Increased APP mRNA expression correlated with reduced CBF.
Conclusions:
- Brain hypoperfusion following silent stroke enhances APP mRNA expression.
- Elevated APP mRNA may contribute to cognitive impairment progression after silent stroke.
- This study provides insights into the molecular basis of dementia development post-silent stroke.
