Recent further info studies by Gibson et al, have shown a role for NF ��B in the regulation of P gp in a mouse microglia cell line, BV 2. Interestingly, in this study, LPS at doses of 1 to 500 ng ml for 12 hours reduced P gp expression, and function Inhibitors,Modulators,Libraries using the fluorescent P gp probe rhodamine 123. In the present study using primary cultures of mouse microglia, 10 ng ml LPS decreased saquinavir accumulation significantly at 6 and 24 hours, presumably due to increased saquinavir efflux. The observed decrease in saquinavir accumulation in the mouse cultures was, however, modest compared to primary rat cultures, suggesting potential species diffe rences. Whether species differences Inhibitors,Modulators,Libraries in molecular mechanisms or specific substrate handling can explain these discrepancies, remains to be confirmed.

Of all the molecular pathways examined in the present study, only inhibition of NF ��B and MEK1 2 reversed the changes in saquinavir accumulation in microglia following LPS exposure. Given that several pro inflam matory factors that are known activators of NF ��B were shown to have no effect, these findings Inhibitors,Modulators,Libraries support that Inhibitors,Modulators,Libraries NF ��B is necessary, but not sufficient to change saquinavir accumulation. These results are in Inhibitors,Modulators,Libraries stark contrast to findings in freshly isolated rat brain capillaries where LPS also initiates acti vation of TLR4, which downstream is connected to alterations in TNF, ET 1, iNOS and PKC acti vation, and ultimately results in increased P glycoprotein protein expression and consequently function in the capillaries. This may not be surprising, as the trans porter profile in glial cells is quite different compared to cells of the BBB.

Most notably, cultured selleck chemicals llc microglia do not express significant levels of Mrp2, Bcrp or mRNA of any of the important SLC uptake transporters expressed at the BBB. Given the redundant nature of the LPS response in microglia, we cannot rule out the possibility that compensatory pathways mask the effects of inhibition or activation of a single pathway in our cell cultures. Further investigations in vivo using knockdown strategies may be helpful to fully elucidate all the path ways that are involved. In summary, we have demonstrated that exposing microglial cells to LPS decreases cellular accumulation of one representative antiretroviral medication. The ability of LPS to significantly decrease saquinavir accu mulation was consistent between microglia derived from multiple species, multiple strains within the same species, and multiple cell preparations. Using PSC833, a non immunosuppressive cyclosporine A analog and potent P glycoprotein inhibi tor, the decrease in saquinavir accumulation in cultured microglia was consistent, in part, with an increase in P glycoprotein mediated drug efflux.