Microvessels isolated from 6, 12, 18 and 24 month old rat brains were incubated for 8 h in serum-free media and the supernatant centrifuged (12,000 g, 15 min). IL-1β (5a) and IL-6 (5b) released into the supernatant were determined using rat custom 9 plex array ELISA (Pierce Biotechnology, MA). For IL-1β, ELISA was also performed using a kit from R<D Systems. Data are mean ± SD from 3 experiments performed in triplicate. * p < 0.05 vs. 6 months; **p < 0.01 vs. 6 months; ***p < 0.001 vs. 6 months.