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

Tn the present study, estrogen receptor (ER)alpha and ER beta genes were found to be differentially expressed in discrete subregions of the rat amygdaloid complex. The amygdala nuclei showing predominant ER alpha mRNA expression included the posterolateral cortical nucleus, amygdala hippocampal area, and lateral dorsolateral nucleus, whereas the amygdala areas with predominant ERP mRNA expression were the medial anterodorsal and central nuclei. Both ER alpha and ER beta 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 ER alpha and ER beta mRNAs. Two weeks of estradiol (170 mu g total) treatment decreased ER alpha mRNA expression levels in the arcuate, ventromedial hypothalamus, and posterolateral cortical amygdala nucleus, but increased ERP mRNA in the arcuate. In the medial amygdala nuclei, only ERP 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. (C) 1998 Elsevier Science B.V.