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. 2010 Mar 10;30(10):1742–1755. doi: 10.1038/jcbfm.2010.36

Figure 7.

Figure 7

E2 signals through ERα and ERβ in isolated brain capillaries. Propylpyrazoletriol, an ERα agonist (A), and diarylpropionitrile, an ERβ agonist (B), decrease luminal BODIPY FL prazosin fluorescence. This indicates that activation of both ERα and ERβ causes downregulation of BCRP transport function in rat brain capillaries. (C) ICI182,780, an ERβ antagonist, does not reverse the E2 effect on luminal BODIPY FL prazosin fluorescence. Methylpiperidinopyrazole, an ERα antagonist, partially reverses the E2 effect. Brain capillary exposure to both methylpiperidinopyrazole (ERα antagonist) and ICI182,780 (ERβ antagonist) completely blocks the E2 effect on luminal BODIPY FL prazosin fluorescence. These data indicate that E2 can signal BCRP downregulation through either ERα or ERβ. (D and E) E2 downregulates BCRP transport activity in brain capillaries from wild-type and ERα (D) and ERβ (E) knockout mice. Note that the E2 effect was only partial ERα knockout mice, which is in agreement with the data shown in (C). In A, B, D, and E, FTC was used as positive control for BCRP inhibition. Each data point represents the mean±s.e.m. for 10 to 15 brain capillaries from a single preparation (pooled tissue from 3 to 10 rats or 20 mice). Units are arbitrary fluorescence units (scale 0 to 255). Statistical comparison: **significantly lower than controls, P<0.01; ***significantly lower than controls, P<0.001. BCRP, breast cancer resistance protein; ER, estrogen receptor; FTC, fumitremorgin C.