MMP-9 and − 2 activities in (frontal cortex) cerebral microvessels in Apo E−/−
mice exposed to mixed vehicle emissions or filtered air. MMP-9 and −2 activities, as shown by in situ zymography, in (frontal cortex) cerebral microvessels in Apo E−/− mice exposed to either mixed vehicle emissions (MVE: 100 μg PM/m3) for 6 hr/day, 30 days (A, C) or filtered air (FA: B, D). A, B scale bar = 10 μm; C, D scale bar = 100 μm. Arrows indicate increased areas of MMP activity (green fluorescence). Background fluorescence (fluorescence present in total image outside of the vessel) was subtracted from each section before statistical comparison between groups. n = 4-5 per group, 3 slides (2 sections each) per sample, 2–3 areas/locations on each sections were used for analysis. *p < 0.050 compared to FA control.