Figure 6. Infusions of a DNA methylation inhibitor in the adult rescues maltreatment-induced deficits in BDNF gene expression in the prefrontal cortex.

(A) The effects of zebularine treatment on methylation of BDNF exon IV DNA (n=3–5/group; male and female adults were derived from 3 mothers). Maltreated animals infused with vehicle demonstrated significantly higher levels of methylation than controls, while zebularine treatment lowered levels of methylation in maltreated-animals (three-way ANOVA with Bonferroni’s post hoc tests; significant effects of infant condition F=18.44, p<0.0001, CpG region F=7.69, p<0.0001, and infant condition × drug interaction F=6.73, p=0.0103). *p-values significant versus adults with a normal infancy infused with vehicle (p 0.05). (B) Average percentage of methylation across the examined CpG sites of exon IV in subjects from panel A (two-way ANOVA with Bonferroni’s post hoc tests; significant effect of infant condition F=13.54, p=0.0003 and infant × drug interaction F=4.94, p=0.0273). *p-value significant versus adults with normal infancy (p<0.0001); #p-value significant versus maltreated-animals infused with vehicle (p=0.05). Maltreated-animals that received zebularine were not significantly different from normal controls. (C) The effects of zebularine treatment on mRNA (n=4–6/group). Animals with a history of maltreatment infused with vehicle demonstrated a significant decrease in both exon IV BDNF mRNA and total BDNF mRNA (exon IX). *p-values significant versus adults with a normal infancy infused with vehicle (exon IV t₅=10.94, p=0.0001; exon IX t₅=2.82, p=0.0373, one-sample t tests) or zebularine (exon IV t₈=2.19, p=0.06; exon IX t₉=2.29, p=0.0474, Student’s two-tailed t test). Zebularine treatment rescued the maltreatment-induced reduction in BDNF mRNA expression (exon IV t₈=3.05, #p=0.0159; exon IX t₁₀=2.91, #p=0.0156, Student’s two-tailed t test), and animals did not differ from normal maternal care controls. Agarose gel images represent total BDNF gene expression (IX). For all panels, error bars represent SEM. NMC=normal maternal care; MAL=maltreatment.