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Phorbol ester stimulates hexose uptake by brain microvessel endothelial cells.
L R Drewes1, M A Broderius, D Z Gerhart
1Department of Biochemistry, School of Medicine, University of Minnesota, Duluth 55812.
Brain Research Bulletin
|November 1, 1988
Summary
Phorbol ester (TPA) significantly increases glucose uptake in brain endothelial cells, suggesting protein kinase C regulates blood-brain glucose transport. This effect is most pronounced in younger cells.
Area of Science:
- Cell Biology
- Neuroscience
- Biochemistry
Background:
- Brain endothelial cells (EC) form the blood-brain barrier, controlling nutrient and waste exchange.
- Understanding glucose transport regulation in brain EC is crucial for neurological health and disease.
Purpose of the Study:
- To investigate the effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on glucose uptake in cultured brain microvessel EC.
- To explore the role of calcium and insulin in TPA-mediated glucose transport regulation.
Main Methods:
- Primary and passaged canine and human brain microvessel EC were cultured.
- Hexose uptake was measured using radiolabeled glucose analogs (3-O-[3H]methyl-D-glucose, 2-[3H]deoxy-D-glucose, D-[3H]glucose) after treatment with TPA, EGTA, A23187, or insulin.
- Actin filament visualization was performed using rhodamine phalloidin.
Main Results:
- TPA treatment (0.1-100 ng/ml) increased hexose uptake 2-10 fold in brain EC.
- The stimulatory effect of TPA was most significant in primary and early-passage cells.
- EGTA and A23187 did not inhibit TPA's effect, and insulin showed no stimulatory effect on glucose uptake.
Conclusions:
- TPA significantly enhances glucose uptake in brain microvessel EC, independent of extracellular calcium levels or insulin.
- These findings suggest that phorbol ester-activated protein kinase C plays a key role in regulating blood-brain glucose transport.