ABSTRACT
To investigate the effect of α-asarone on the function and expression of P-glycoprotein(P-gp)in rat brain microvascular endothelial cells(rBMECs). 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. The rBMECs,stimulated by glutamine,showed a high expression of P-gp(=1.924,=0.020)/Mdr1a(=1.788,=0.019) compared to the normal rBMECs.The treatment with 25.0(=1.924,=0.025;=1.788,=0.017) and 50.0 μg/μl(=1.924,=0.035;=1.788,=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. 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.
ABSTRACT
The present study aimed at investigating the effects of Puerarin (PR), a major isoflavonoid isolated from the Chinese medicinal herb Puerariae radix, on bone metabolism and the underlying mechanism of action. The in vivo assay, female mice were ovariectomized (OVX), and the OVX mice were fed with a diet containing low, middle, and high doses of PR (2, 4, and 8 mg·d(-1), respectively) or 17β-estradiol (E2, 0.03 μg·d(-1)) for 4 weeks. In OVX mice, the uterine weight declined, and intake of PR at any dose did not affect uterine weight, compared with the control. The total femoral bone mineral density (BMD) was significantly reduced by OVX, which was reversed by intake of the diet with PR at any dose, especially at the low dose. In the in vitro assay, RAW264.7 cells were used for studying the direct effect of PR on the formation of osteoclasts. PR reduced the formation of tartrate resistant acid phosphatase (TRAP)-positive multi-nucleated cells in the RAW 264.7 cells induced by receptor activator for nuclear factor-κB Ligand (RANKL). MC3T3-E1 cells were used for studying the effects of PR on the expression of osteoprotegerin (OPG) and RANKL mRNA expression in osteoblasts. The expression of OPG mRNA and RANKL mRNA was detected by RT-PCR on Days of 5, 7, 10, and 12 after PR exposure. PR time-dependently enhanced the expression of OPG mRNA and reduced the expression of RANKL mRNA in MC3T3-E1 cells. In conclusion, our results suggest that PR can effectively prevent bone loss in OVX mice without any hyperplastic effect on the uterus, and the antiosteoporosis activity of PR may be related to its effects on the formation of osteoclasts and the expression of RANKL OPG in osteoblasts.