THE DISTRIBUTION OF ESTROGEN RECEPTOR-BETA MESSENGER-RNA IN THE RAT HYPOTHALAMUS

The recent cloning of a second form of the estrogen receptor (ER-beta) has made it possible to map the distribution of ER-beta mRNA-containi ng perikarya in the rat hypothalamus. The present in situ hybridizatio n histochemical studies have detected ER-beta mRNA in the medial preop tic area; the anterior periventricular, paraventricular, supraoptic, a rcuate, medial tuberal and medial mammillary nuclei; the bed nucleus o f the stria terminalis, and zona incerta. As previously described for the classical ER (ER-alpha) mRNA, a dense accumulation of ER-beta mRNA -expressing perikarya is present in the medial preoptic area and bed n ucleus of the stria terminalis. In contrast, ER-beta mRNA was also con centrated in the paraventricular and supraoptic nuclei, brain regions which contain little or no ER-alpha mRNA. Moreover, the arcuate and ve ntromedial nuclei, areas with abundant ER-alpha, contain only a weak l evel of ER-beta hybridization signal. The description of ER-beta mRNA- containing perikarya in the int hypothalamus provides a foundation for further morphological and physiological studies aimed at elucidating the role of ER-beta in the hypothalamus. (C) 1996 by Elsevier Science Inc.