[The tight junction proteins ZO-1, occludin and actin participate in the permeability increasing of blood-brain barrier induced by hypoxia-ischemia].
OBJECTIVE
To study the changes of blood-brain barrier-tight junction (BBB-TJ) proteins ZO-1, occludin and actin following hypoxia-ischemia (HI) in order to explore the possible mechanism of permeability increasing of blood-brain barrier (BBB) induced by HI.


METHODS
BBB models were established by co-culture of cell ECV304 and astrocytes (AS) in vitro, then randomly assigned to control and HI groups. Transmission electron microscope was used to observe the changes of BBB-TJ. The distribution of actin was determined by direct-immunofluorescence microscope. Definite permeability of BBB models by 125I-BSA was detected by gamma events-per-unit-time meter. Expression of actin, ZO-1 and occludin was detected by Western blot.


RESULTS
After 10-day culture, endothelial cells connected tightly, with plenty of TJ which was smooth, continuous and of high density, in the BBB models. After 5 hrs of HI, the TJ was opened with intercellular gaps formation. The direct immunofluorescence showed that the peripheral filament bands became blurred, the cell-cell junction loosened and fissure appeared in the HI group. The permeability of 125I-BSA in the HI group increased significantly compared with the control group (P<0.01). Expression of ZO-1 decreased markedly, while expression of actin and occludin was not different in the HI group compared with the control group.


CONCLUSIONS
The changes in occludin distribution and decreased expression of ZO-1 lead the reorganization of BBB-actin protein, which may be one of the mechanisms of permeability increasing of BBB following HI.
Wu
Li-Wen
LW
Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China.
Yin
Fei
F
Peng
Jing
J
Wang
Wei-Dong
WD
Gan
Na
N
D000199:Actins / Q000032:analysis / Q000502:physiology*; D000818:Animals; D001812:Blood-Brain Barrier; D005260:Female; D000860:Hypoxia / Q000378:metabolism*; D007511:Ischemia / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000502:physiology*; D062793:Occludin; D010539:Permeability; D010750:Phosphoproteins / Q000032:analysis / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019108:Tight Junctions / Q000648:ultrastructure; D062826:Zonula Occludens-1 Protein
D000199:Actins; D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D010750:Phosphoproteins; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein