Tet enzyme gene expression is highest at birth. Expression of Tet1, Tet2 and Tet3 mRNA at postnatal days 1, 7, 25, and 60 in a) the preoptic area of the hypothalamus (POA); b) the ventromedial nucleus of the hypothalamus (VMH); and c) the hippocampus. The expression of all three Tet enzymes was highest in newborns, and abruptly decreased by day 7. Different lower-case letters indicate statistically significant differences (P < 0.05). Data are mean ± SEM. N = 19–25 mice per age.