Down-regulation of P-glycoprotein expression contributes to an increase in Danshensu accumulation in the cerebral ischemia/reperfusion brain.

P-glycoprotein (P-gp) plays a key role in the distribution and elimination of many clinically important therapeutic substances. P-gp inhibition is capable of increasing the concentration of various drugs in the brain. Danshensu is a main hydrophilic constituent of Salvia miltiorrhiza Bunge which is used traditionally to treat cerebrovascular diseases. In the present study, the effects of cerebral ischemia/reperfusion on the transport of Danshensu in the brain were observed by assaying the concentration at 15, 30 and 60 min after cerebral ischemia/reperfusion in the brain of rats. Furthermore, the expression of P-gp in the brain was also measured. Results showed that Danshensu concentrations in the ischemic hemisphere significantly increased compared to those in the non-ischemic hemisphere and the brain of the sham group. P-gp expression was inhibited by cerebral ischemia/reperfusion to some extent, and down-regulated much more by Danshensu treatment. The findings indicate that the down-regulation of P-gp expression induced by both cerebral ischemia/reperfusion and Danshensu treatment contributes to the increase of Danshensu accumulation in the brain.