In Vitro FITC-Dextran Permeability Assay.

Brain endothelioma bEnd.3 cells were cultured in DMEM, supplemented with 10% FBS, and harvested by detachment with TrypLE (Thermo Fisher Scientific). For in vitro permeability assay, bEnd.3 cells or isolated primary endothelial cells were seeded on fibronectin-coated (7 µg/mL, Sigma-Aldrich) or collagen-precoated Transwell plates (0.4 µm pore size; Thermo Fisher Scientific) and cultured for 3 d. Cells were then incubated with 5 µM corticosterone (Sigma-Aldrich) and 1 mg/mL 40-kDa FITC-dextran (Sigma-Aldrich) for 20 h. Medium from the receiver tray was collected, diluted to 1:20 in PBS, and fluorescence was measured with a spectrophotometer (Perkin-Elmer) at an excitation wavelength of 490 nm and emission of 529 nm.