Distribution of estrogen receptor-β messenger ribonucleic acid in the male sheep hypothalamus

As a first step in determining possible influences of the newly discovered estrogen receptor (ER)-β on reproduction, we have localized mRNA for ER-β within the male sheep hypothalamus using in situ hybridization and a rat ER-β cRNA probe. Highest amounts of hybridization signal were observed in the preoptic area (POA), bed nucleus of the stria terminalis, paraventricular nucleus, and supraoptic nucleus. Relatively moderate amounts of hybridization signal were observed in the retrochiasmatic area (RCH), anterior hypothalamic area, dorsomedial hypothalamus, and lateral hypothalamus. Only a low level of hybridization signal was observed in the ventromedial hypothalamus, suprachiasmatic nucleus, and arcuate nucleus. The presence of ERβ mRNA in several areas of the male sheep hypothalamus suggests multiple functions for this receptor. The distribution of ER-β in the ovine hypothalamus was similar to that described for the rat, suggesting a high degree of functional conservation across species. A role for ER-β in influencing reproduction is suggested by its presence in the POA and RCH, regions of the hypothalamus that control reproduction.