P-glycoprotein expression in brain capillary endothelial cells after focal ischaemia in the rat.
P-glycoprotein (P-gp) is expressed not only in tumour cells but also in some normal tissues including brain capillaries. We investigated whether or not P-gp was expressed in the capillary endothelial cells of a rat focal ischaemic brain. The brains were immunohistochemically studied for Factor VIII, glial fibrillary acidic protein (GFAP), and P-gp. Endothelial gamma-glutamyl transpeptidase (gamma-GTP) activity, which is thought to be induced by glial cells, was also studied histochemically. The P-gp positive endothelial cells disappeared in the ischaemic lesion by post-ischaemic day 3. Factor VIII-positive regenerating capillaries were first observed on day 3 without P-gp expression. The P-gp positive endothelial cells began to reappear on day 5, and were detected in all the endothelial cells by day 8. The P-gp expression in endothelial cells showed a similar pattern as that of gamma-GTP, and seemed to correlate with GFAP-positive reactive astrocytes. The newly-formed brain capillaries thus appeared to have a potential to express P-gp in abnormal pathogenic conditions as cerebral infarction, and our present study also suggested that P-gp in the brain capillaries might therefore be expressed in conjunction with glial cells.
Samoto
K
K
Department of Neurosurgery, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Ikezaki
K
K
Yokoyama
N
N
Fukui
M
M
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis*; D000818:Animals; D001812:Blood-Brain Barrier; D001923:Brain Chemistry / Q000502:physiology*; D002196:Capillaries / Q000166:cytology / Q000378:metabolism; D002199:Capillary Permeability / Q000502:physiology; D002536:Cerebral Arteries / Q000502:physiology; D004285:Dogs; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005169:Factor VIII / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000276:immunology / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D007150:Immunohistochemistry; D002546:Ischemic Attack, Transient / Q000378:metabolism* / Q000473:pathology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D005904:Glial Fibrillary Acidic Protein; D006160:Guanosine Triphosphate; D005169:Factor VIII