Differential distribution and regulation of estrogen receptor-α and -β mRNA within the female rat brain

Abstract

In the present study, estrogen receptor (ER)α and ERβ genes were found to be differentially expressed in discrete subregions of the rat amygdaloid complex. The amygdala nuclei showing predominant ERα mRNA expression included the posterolateral cortical nucleus, amygdala hippocampal area, and lateral dorsolateral nucleus, whereas the amygdala areas with predominant ERβ mRNA expression were the medial anterodorsal and central nuclei. Both ERα and ERβ mRNAs were highly expressed in the medial posterodorsal nucleus. In addition to the discrete anatomical expression patterns, there appeared to be a differential regulation by estradiol of the ERα and ERβ mRNAs. Two weeks of estradiol (170 μg total) treatment decreased ERα mRNA expression levels in the arcuate, ventromedial hypothalamus, and posterolateral cortical amygdala nucleus, but increased ERβ mRNA in the arcuate. In the medial amygdala nuclei, only ERβ mRNA levels were altered (reduced) by estradiol treatment. These results suggest that estrogen can modulate behaviors and functions mediated by the amygdala and hypothalamus via differentially regulated ER subtypes.