Figure 3.

Inhibition of DNMT alters bdnf gene expression and DNA methylation in hippocampus in vivo. A, The diagram represents the histology from animals for which needle tips for intra-CA1 infusions were confirmed before biochemistry studies in B–D. B, Reverse transcriptase quantitative real-time PCR was used to determine the effect of intra-CA1 infusions of zebularine (DNMT inhibitor) on basal bdnf mRNA levels relative to saline control. cDNA products for bdnf exons I, IV, VI, and IX indicate that bdnf mRNA is artificially increased in area CA1 of hippocampus with zebularine treatment in vivo (I, t₍₆₎ = 2.71, p = 0.0352; IV, t₍₆₎ = 3.27 p = 0.0171; VI, t₍₅₎ = 3.07, p = 0.0278; IX, t₍₆₎ = 3.26, p = 0.0173, n = 6–7). Products for exon II mRNA did not change with zebularine. C, Correlative studies from the same animals used in B. Zebularine significantly decreased levels of methylated bdnf exons I, II, IV, and VI DNA in area CA1 of hippocampus (I, t₍₆₎ = 13.33, p = 0.0001; II, t₍₅₎ = 2.73, p = 0.0411; IV, t₍₆₎ = 4.371, p = 0.0047; VI, t₍₆₎ = 2.82, p = 0.0304, n = 6–7). The solid line across the bars represents normalized naive control levels. D, Bisulfite sequencing analysis performed on 12 CpG sites near the transcription initiation site of exon IV show percentage of cytosine residues at specific CpG sites that were demethylated after zebularine treatment (Student's t test, *p < 0.05, **p < 0.01, ***p < 0.001, compared with naive controls).