Figure 4. Increased acetylated histone 3 and acetylated histone 4 levels in retinal ganglion cells after histone deacetylase inhibitor treatment. A-D: Intensity of acetylated histone (AcH) 3 and AcH4 expression in retinal ganglion cells (RGCs) with or without histone deacetylase inhibitor (HDACi) treatment after 24 h in culture. A, C: In comparison to controls, sodium butyrate (SB) 0.1 mM significantly increased the amount of AcH3 (A, *p=0.0119) and AcH4 (C; *p=0.0105) in RGCs. The expression quotients were 1.7 and 1.4, respectively, indicating an apparent hyperacetylation after SB treatment. The horizontal line in A+C indicates, that the difference in hyperacetylation was statistically significant. B, D: Valproic acid (VPA) slightly increased AcH3 (B, p=0.1368) and AcH4 (D, p=0.3326) over baseline levels in controls; however, differences were not statistically significant (the expression quotients were 1.2 and 1.1, respectively).