Abstract: Objetive To investigate the effect of Qingkailing injection on the expression of Toll-like receptor 4 (TLR4), gp91^phox and zonula occludens-1 (ZO-1) in cerebrovascular endothelial cells induced by hypoxia activation of microglias.Methods BV2 microglia cells were divided into six groups. They were cultured in serum-free DMEM, while the Qingkailing groups of low, middle and high dosages were cultured with 0.0625%, 0.125% and 0.25% Qingkailing injection, respectively, and minocycline group with minocycline of 200 nmol/L. The groups other than control group underwent hypoxia for 24 hours and reoxygenation for 24 hours. Then, the medium of microglia was put into the medium of Balb/c endothelial cells for 24 hours. The cell viability of endothelial cells was measured with CCK-8, the concentration of nitric oxide (NO) was detected with colorimetry, and the experission of TLR4, gp91^phox and ZO-1 was detected with Western blotting. Results Compared with the control group, the cell viability and the expression of ZO-1 decreased in the model group (P < 0.01), while the concentration of NO and the expression of TLR4 and gp91^phox increased (P < 0.05). Compared with the model group, the cell viability and the expression of ZO-1 increased in the Qingkailing groups and the minocycline group (P < 0.05), while the concentration of NO and the expression of TLR4 and gp91^phox decreased (P < 0.05). Conclusion Qingkailing injection may enhance the survival and function of cerebrovascular endothelial cells by inhibiting the hypoxia activation of microglias, reducing the expression of TLR4 and gp91^phox, and increasing the expression of ZO-1.

Key words: ischemic stroke, Qingkailing injection, blood-brain barrier, microglia, endothelial cell