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 r at ER-P cRNA probe. Highest amounts of hybridization signal were observed i n the preoptic area (POA), bed nucleus of the stria terminalis, paraventric ular nucleus, and supraoptic nucleus. Relatively moderate amounts of hybrid ization signal were observed in the retrochiasmatic area (RCH), anterior hy pothalamic area, dorsomedial hypothalamus, and lateral hypothalamus. Only a low level of hybridization signal was observed in the ventromedial hypotha lamus, suprachiasmatic nucleus, and arcuate nucleus. The presence of ER-bet a mRNA in several areas of the male sheep hypothalamus suggests multiple fu nctions for this receptor. The distribution of ER-beta in the ovine hypotha lamus was similar to that described for the rat, suggesting a high degree o f functional conservation across species. A role for ER-beta in influencing reproduction is suggested by its presence in the POA and RCH, regions of t he hypothalamus that control reproduction.