[Effect of α-asarone on the Function and Expression of P-glycoprotein in Rat Brain Microvascular Endothelial Cells]

Objective To investigate the effect of α-asarone on the function and expression of P-glycoprotein(P-gp)in rat brain microvascular endothelial cells(rBMECs). Methods rBMECs were exposed to L-glutamate(100 μmol/L) for 30 mins to induce the overexpression of P-gp/multidrug resistance gene 1a(Mdr1a)on the cell membranes,which mimicked the overexpression of P-gp/Mdr1a in blood brain barrier(BBB) when drug-resistant epilepsy attacked.MTT assay was used to detect the safe range of α-asarone concentration.The model cells were intervened with different concentrations of α-asarone at 12.5,25.0,and 50.0 μg/μl for 24 hours.After the treatment of α-asarone,the expression and the function of P-gp/Mdr1 were measured by Western blotting,real-time PCR,and intracellular rhodamine 123 accumulation assays. Results The rBMECs,stimulated by glutamine,showed a high expression of P-gp(F=1.924,P=0.020)/Mdr1a(F=1.788,P=0.019) compared to the normal rBMECs.The treatment with 25.0(F=1.924,P=0.025;F=1.788,P=0.017) and 50.0 μg/μl(F=1.924,P=0.035;F=1.788,P=0.026) α-asarone significantly depressed the expression of P-gp/Mdr1a.The treatment with 25.0 and 50.0 μg/μl α-asarone significantly increased intracellular accumulation of Rhodamine 123 by 40% and 60% respectively. Conclusions α-asarone down-regulates the high expressions of P-gp and Mdr1a mRNA in rBMECs induced by L-glutamate.Moreover and increases intracellular accumulation of rhodamine-123.Thus,α-asarone may reverse drug resistance in P-gp-mediated drug-resistant epilepsy.