AIM To investigate the protective effects and the mechanism of the Liuwei Dihuang Pills on mouse brain microvascular endothelial(bEnd.3)cells damaged by β-Amyloid protein1-40(Aβ1-40).METHODS CCK8 method was used to detect the effects of Aβ1-40 and medicated serum of Liuwei Dihuang Pills(MSLDP)on cell activity,and to screen the appropriate concentration.bEnd.3 cells of the control group,the Aβ1-40 group,the MSLDP+Aβ1-40 group and the MSLDP group had their low density lipoprotein-associated protein 1(LRP1),receptor for advanced glycation end products(RAGE),matrix metalloproteinase-2(MMP-2),MMP-9,scaffold protein zonule protein-1(ZO-1)detected by Western blot.bEnd.3 cells assigned into the control group,the Aβ1-40 group,the FPS-ZM1(RAGE inhibitor)+Aβ1-40 group and the FPS-ZM1+Aβ1-40+MSLDP group had their expressions of RAGE,MMP-9,MMP-2 and ZO-1 detected by Western blot as well.RESULTS The cell activity of bEnd.3,was dose-dependently decreased by Aβ1-40(P<0.01),but was protected by MSLDP(P<0.05,P<0.01).And 10 μmol/L Aβ1-40 and 10%MSLDP were selected for subsequent experiments.Compared with the control group,the Aβ1-40 group displayed increased protein expressions of RAGE,MMP-2 and MMP-9(P<0.01),decreased protein expressions of LRP1,ZO-1 and BDNF(P<0.05,P<0.01),and decreased fluorescence intensities of LRP1 and ZO-1(P<0.01).Compared with the Aβ1-40 group,the MSLDP group shared decreased expressions of RAGE,MMP-2,MMP-9 proteins and RAGE fluorescence intensity(P<0.05,P<0.01),and increased expressions of LRP1,ZO-1 and BDNF proteins,and the fluorescence intensity of LRP1 and ZO-1(P<0.05,P<0.01);the Aβ1-40+FPS-ZM1 group displayed decreased protein expressions of MMP-2,MMP9 and RAGE(P<0.05,P<0.01),and increased ZO-1 protein expression(P<0.05);and the Aβ1-40+FPS-ZM1+ MSLDP group displayed an even more decreased protein expressions of MMP-2,MMP9 and RAGE(P<0.01),increased ZO-1 protein expression(P<0.01)due to the the combination use of FPS-ZM1 and MSLDP.CONCLUSION Liuwei Dihuang Pills can protect the tight junction of bEnd.3 injured by Aβ1-40 and neurovascular units from Alzheimer's disease by alleviating the dysfunction of the blood-brain barrier via RAGE-mediated MMP-2/MMP-9 pathway inhibition.