Platelet activating factor induces blood brain barrier permeability alteration in vitro

The purposes of this article were to investigate whether blood brain barrier (BBB) permeability is altered after platelet activating factor (PAF) induced injury in vitro and elucidate the preliminary possible mechanisms of it. MTT method was used to observe cell damage after PAF incubation with rat brain microvessel endothelial cells (RBMECs). Intracellular concentrations of Nimodipine in normal and PAF injured RBMECs were estimated by LC-MS/MS analytical method to estimate BBB permeability. Accumulation of P-glycoprotein (P-gp) substrate rhodamine 123 in normal or PAF injured RBMECs was measured with Poly Immune Analysis System-1420 to evaluate the function of P-gp on RBMECs. Intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression levels in RBMECs were assayed by RT-PCR and flow cytometry respectively. Results showed that after RBMECs were incubated with 1 μM PAF for 24h, cell survival rate was decreased, and intracellular concentrations of Nimodipine were increased evidently. Rhodamine 123 accumulation between normal and PAF injured cells has no significant difference, but ICAM-1 mRNA and protein expression were increased remarkably in PAF injured cells, which could be inhibited by PAF antagonists. In conclusion, the present study demonstrated that BBB permeability was increased after PAF incubation, and which may be due to ICAM-1 up-regulating but not P-glycoprotein function alteration.