Regulation of estrogen receptor alpha gene expression in the mouse prefrontal cortex during early postnatal development

Estrogens have many functions in the developing rodent brain, and most of these depend on the presence of estrogen receptors. Understanding how expression of these receptors are regulated is crucial for understanding the roles of estradiol in the male and female brain during development In rodents, the prefrontal cortex (PFC) has been shown to be involved in working memory, attention, and behavioral inhibition. Many studies have demonstrated an effect of estradiol on sex difference in these functions attributed to differences in the PFC. We have previously demonstrated that estrogen receptor alpha (ER alpha) expression decreases in the isocortex across early postnatal development. This decrease corresponds with an increase in methylation of many sites along the ER alpha promoter. Here we have examined both ER alpha and ER beta mRNA expression in the PFC to determine if methylation also plays a role in this important brain region. We investigated expression of alternate promoters for ER alpha and methylation of CpG sites along two of these promoters. We found that the pattern of ER alpha mRNA expression in PFC was similar to the pattern of ER alpha expression in the isocortex and that there were no sex differences in the level of expression across development. We did, however, find subtle differences in promoter expression and methylation that may indicate a sex-specific difference in PFC during development resulting in a difference in adult response.