We investigated the time kinetics of P-glycoprotein (P-gp), a membrane bound drug efflux pump for many anti-cancer drugs in multidrug resistant cells, using a rat ischemic brain model. Frozen sections of the brain were studied immunohistochemically with anti-Factor VIII antibody for endothelial cells, with anti-glial fibrillary acidic protein (GFAP) antibody for reactive astrocytes, and with MC6-4 monoclonal antibody for P-gp. A putative blood-brain barrier (BBB) marker, gamma-glutamyl transpeptidase (gamma-GTP), and the progression of the brain edema were also studied. P-gp positive endothelial cells disappeared in the ischemic lesion by post-ischemic Day 3. Factor VIII-positive regenerating capillaries were first observed on Day 3 without P-gp expression when the brain edema reached a maximum. P-gp positive endothelial cells began to reappear on Day 5, and were detected in all endothelial cells by Day 8. The time kinetics of P-gp expression in the endothelial cells showed a similar pattern as that of gamma-GTP, and its induction is associated with GFAP-positive reactive astrocytes. These results suggest that P-gp might play an important role in maintaining the BBB function in conjunction with glial cells.
CITATION STYLE
Samoto, K., Ikezaki, K., Yokoyama, N., & Fukui, M. (1994). P-glycoprotein expression in brain capillary endothelial cells after focal ischemia in rat. Acta Neurochirurgica. Supplementum, 60, 257–260. https://doi.org/10.1007/978-3-7091-9334-1_68
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