Impact of pubertal onset on region-specific Esr2 expression

In female rats, pubertal onset is associated with maturation of the medial prefrontal cortex (mPFC) and mPFC-mediated behaviors. These behavioral and anatomical changes are likely due to effects of estrogen at the nuclear estrogen receptor beta (ER{beta}), which is expressed at higher levels than the estrogen receptor alpha (ER) isoform in the adult mPFC. Researchers have previously quantified ER{beta} protein and Esr2 RNA in rodents during early postnatal development and adulthood, but an adolescent-specific trajectory of this receptor in the mPFC has not been documented. Given that levels of Esr2 can fluctuate in the presence or absence of estrogens, puberty and the subsequent rise in gonadal hormones could influence ER{beta} expression in the adolescent brain. To further explore this, we used RNAscope to quantify the amount of Esr2 mRNA in pre-pubertal adolescent, recently post-pubertal adolescent, and adult female rats. We show here that Esr2 expression decreases significantly in the mPFC, striatum and motor cortex between pre-pubertal adolescence and adulthood. In the mPFC, this decrease occurs rapidly at pubertal onset, with no significant decrease in Esr2 levels between the recently post-pubertal and adult cohort. In contrast in the striatum and motor cortex, there were no significant differences in the amount of Esr2 between pre- and post-pubertal females. Insofar as the amount of Esr2 is proportional to functional ER{beta}, these results suggest ER{beta} decreases in a region-specific pattern in response to pubertal onset and highlight a role for this receptor in the maturational events that occur in the female rat mPFC at puberty.