Fig. 4.

Effects of PM and noise exposure on arteriolar vascular function and oxidative stress in the brain and stress response hormones. Vascular function was assessed in cerebral arterioles (A) and in retinal arterioles (B). The arteriole vasodilation was assessed by treatment with the nitric oxide donor sodium nitroprusside (SNP) and the endothelium-dependent vasodilator and endogenous eNOS activator acetylcholine (ACh). Endothelial function (ACh-response) was impaired by the single exposures and additively in the PM-noise combined exposure. The endothelium-independent vasoreactivity to SNP was not affected in any exposure group (for vasoconstriction by U46619 see suppl. Fig. S4). The stress hormones, adrenaline and noradrenaline, were increased in plasma of the noise-exposed animals (C). Protein expression of phosphorylated myristoylated alanine-rich C-kinase substrate (P-MARCKS) and phagocytic NADPH oxidase subunit, NOX-2, was upregulated mostly in the noise-exposed mice (D). Dihydroethidium fluorescence microtopography in sections of cerebral (E), and retinal (F) arterioles (the arrows point to the vascular cross-sections in the retina) showed an increase all exposure groups with displaying additive effect of noise and PM. Representative fluorescence microscope images are shown below the quantification. Representative original blots are shown besides the quantification. Data are presented as mean ± SEM and individual values are shown where possible. The statistics was performed from n = 8 (A), 6 (B), 7–12 (C), 6 (D) and 7 (E, F) independent experiments. The statistical significance of p < 0.05 is represented with (*), p < 0.01 is represented with (**), p < 0.001 is represented with (***), and p < 0.0001 is represented with (****); GCL: ganglion cell layer; IPL: inner plexiform layer; INL: inner nuclear layer; OPL: outer plexiform layer; ONL: outer nuclear layer. The scale bar at (E) is 30 μm and at (F) 50 μm.