Environmental enrichment modulates 5-hydroxymethylcytosine dynamics in hippocampus.

Gene-environment interactions mediated at the epigenetic level may provide an initial step in delivering an appropriate response to environmental changes. 5-Hydroxymethylcytosine (5hmC), a DNA base derived from 5-methylcytosine (5mC), accounts for ~40% of modified cytosine in the brain and has been implicated in DNA methylation-related plasticity. To identify the role of 5hmC in gene-environment interactions, we exposed both young (6-week-old) and aged (18-month-old) mice to both an enriched environment and a standard environment.