In utero lead (Pb) exposure and neuron-specific DNA methylation in mice

Lead (Pb) exposure is associated with a wide range of neurological deficits. Epigenetic changes, such as DNA methylation, may be impacted by environmental exposures and can affect neurodevelopmental outcomes over the life-course. Mating mice were obtained from a C57BL/6J background agouti Avy strain. Virgin dams (a/a) were randomly assigned exposure to 2.1 ppm (low) or 32 ppm (high) Pb-acetate through the drinking water, started two weeks prior to mating with viable yellow agouti male mice (Avy/a) and continued throughout gestation and three weeks after birth. At 10 months of age, we separated brain NeuN+ (a marker for neuronal nuclei) neuronal nuclei from NeuN non-neuronal nuclei in mice. We investigated neuron specific genome-wide promoter DNA methylation associated with early-life Pb exposures using the Roche NimbleGen Mouse DNA methylation 3x720K CpG island Promoter Array. Sample pooling was necessary to reach the amount of genomic DNA necessary to perform hybridization. Three pooled samples were used for each control, low, and high Pb exposure group, resulting in nine total pooled samples. Each pool consisted of DNA from at least two isogenic mice.