Regulation of H4 acetylation at gene promoters after acute or chronic ECS. Levels of H4 acetylation at the synaptophysin and β-tubulin promoters, two genes with expression that is not regulated by ECS, are compared with the levels of H4 acetylation at the c-fos promoter at 30 min, 2 hr, and 24 hr after acute or chronic ECS. Note the robust, time-dependent regulation of H4 acetylation at the c-fos promoter, but lack of regulation at the synaptophysin and β-tubulin promoters, under these conditions. Data are expressed as means ± SEM (n = 4-6 in each treatment group). Control (sham-ECS) values are 1± the following SEMs: 0.02 (c-fos, 30 min), 0.05 (c-fos, 2 hr), 0.04 (c-fos, 24 hr), 0.04 (β-tubulin, 2 hr), 0.06 (β-tubulin, 24 hr), 0.05 (synaptophysin, 30 min), and 0.03 (synaptophysin, 2 hr). *p < 0.05, different from control; †p < 0.05, different from acute ECS-24 hr, by t test.