ABSTRACT
Objective To explore the effect of lysophosphatidic acid(LPA)on blood-brain barrier(BBB) permeability and its possible mechanism.Methods LPA or LPA+suramin(L+S)were stereotaxically injected into the right eaudate nucleus in SD rats in vivo.Evans blue(EB)was used to quantitatively measure the permeability of BBB at different time points.The expression of matrix metalloproteinase-9 was detected by immunohistochemistry technique.The pathological ultrastruetural changes of BBB were assessed by transmission electron microscopy.Results The BBB permeability began to increase after LPA administered into ipsilateral eaudate nucleus,and reached the peak at 24h.Then the permeability of BBB gradually lowered after 48h.In comparison with the same time points of control group,there were quite significant differences(P＜0.01).After L+S was injected,the change of BBB permeability had differences in comparison with those of LPA group in the same time points,(P＜0.05).MMP-9 positive cells were mainly vascular endothelial cells.The numbers of MMP-9 positive blood vessels grew at 6h in LPA group,and the expression of it reached maximum at 24h,then the number of it decreased at 48h,showing significant statistical differences in comparison with the L+S group(P＜0.01),It was observed microscopically that ultrastrueture of BBB of the LPA group was changed sharply,such as basement membrane roughed and fragmented,astroeyte end-feet swolled markedly and perivaseular space enlarged obviously.But there were no remarkable changes in BBB in L+S group.Conclusion LPA can induce increase of BBB permeability and its possible mechanism is the strong expression of MMP-9 protein produeted by endothelial cells through the mediation of LPA receptor,leading to degradation of basement membrane.