Sex and age differences in the distribution of estrogen receptors in mice

Estrogen receptors (ER alpha and ER beta) are crucial for the regulation of socio-sexual behaviors and the organization of sex-specific neural networks in the developing brain. However, how the distribution patterns of ER alpha and ER beta change throughout life is unclear. Using genetically modified ER beta-RFPtg mice, we investigated the distribution of ER alpha, ER beta, and their colocalization in the ventromedial nucleus of the hypothalamus (VMH), anteroventral periventricular nucleus (AVPV), and bed nucleus of stria terminalis (BNST) from postnatal days (PD) 0 to 56. ER alpha expression was higher in females that showed an increase after PD14 in all brain regions, whereas ER beta-RFP expression pattern was markedly different among the regions. In the VMH, ER beta-RFP was highly expressed on PD0 and PD7 but decreased drastically to very low expression afterward in both sexes. In contrast, ER beta-RFP expression was higher in females compared to males in the AVPV but lower in the BNST throughout life espe-cially late-and post-pubertal periods. Our results demonstrating that ER alpha and ER beta-RFP expression changed in a sex-, age-and region-specific manner contribute to further clarification of the mechanisms underlying estrogen -dependent organization of the brain in both sexes.

Automated summary

Estrogen receptors (ER alpha and ER beta) play a crucial role in regulating socio-sexual behaviors and organizing sex-specific neural networks in the developing brain. However, the changes in distribution patterns of ER alpha and ER beta throughout life are not well understood. This study used genetically modified ER beta-RFPtg mice to investigate the distribution of ER alpha, ER beta, and their colocalization in specific brain regions from postnatal days (PD) 0 to 56. The results showed that the expression of ER alpha increased in females after PD14 in all brain regions, while the expression pattern of ER beta-RFP varied among the regions.