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

As a first step in determining possible influences of the newly discovered estrogen receptor (ER)-beta on reproduction, we have localized mRNA for ER-beta within the male sheep hypothalamus using in situ hybridization and a rat ER-beta 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 ER-beta mRNA in several areas of the male sheep hypothalamus suggests multiple functions for this receptor. The distribution of ER-beta 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-beta in influencing reproduction is suggested by its presence in the POA and RCH, regions of the hypothalamus that control reproduction.