RESUMO
[ ABSTRACT ] AIM: To study the effect of idazoxan on the permeability of inflammatory blood-brain barrier ( BBB) model in vitro and the expression of tight junction protein ZO-1.METHODS:In vitro BBB model was established by murine brain endothelial cell line bEnd.3 incubated for 7 d.The cells were treated with TNF-α(10 nmol/L) for addi-tional 24 h to establish the inflammatory BBB model, which was pretreated with IDA at doses of 50, 100 and 200μmol/L, respectively.The permeability was measured using fluorescein isothiocyanate-conjugated dextran (FD-40, MW 40,000), the expression of ZO-1 was detected by Western blot analysis, the distribution of ZO-1 was observed by immunofluores-cence, and the mRNA expression of MMP-9/TIMP-1 was measured by RT-PCR.RESULTS:After incubated for 7 d, b. End3 cells converged to be confluent monolayer with low permeability.The inflammatory BBB model induced by TNF-αtreatment displayed much higher permeability with decreased expression of tight junction protein ZO-1, destroyed distribu-tion of ZO-1 and increased mRNA expression of MMP-9.When pretreated with IDA, the permeability was greatly de-creased, the expression of ZO-1 was greatly increased, the abnormal distribution of ZO-1 was greatly ameliorated and the mRNA expression of MMP-9 was obviously reduced.The effect was most significant in IDA ( 200 μmol/L )-pretreated group (P<0.01).CONCLUSION:IDA directly acts on brain endothelial cells to reduce the expression of MMP-9, in-crease the expression of tight junction protein ZO-1 and ameliorate the destroyed distribution of ZO-1 in the inflammatory BBB, thus reversing the abnormally elevated permeability in a inflammatory BBB model in vitro induced by TNF-α.
