title: Sex and region-specific regulation of oestrogen receptor beta in the rat hypothalamus.
abstract: Sexual dimorphism in the expression of oestrogen receptor (ER)beta mRNA and protein was characterized in the rostral forebrain of the rat and its dependence on the neonatal endocrine environment was revealed. We present novel data demonstrating, in gonadectomized adult rats, that the amount of oestrogen caused a significant reduction in the number of ERbeta messages and protein in the ventromedial nucleus in both sexes, but no such effects were detected in the preoptic area or the amygdala. In gonadectomized females, more so than in males, the ventromedial nucleus of the adult rat contained a significantly larger number of ERbeta-positive neurones both in terms of ERbeta mRNA and protein. In the juvenile rat on day 14, sex difference in ERbeta expression was already observed in the ventromedial nucleus. Treatment of neonatal females with oestrogen from days 1-10 or neonatal orchidectomy of males reversed the sex difference in the ventromedial nucleus when observed on day 14, showing that the neonatal presence of oestrogen had caused irreversible masculinization of this structure. Our results suggest that sex-specific expression of ERbeta is patterned by perinatal hormone exposure: down-regulation of ERbeta caused by oestrogen in a region-specific manner.
authors.affiliation: Department of Physiology, Nippon Medical School, Tokyo, Japan. orikasa@nms.ac.jp
authors.forename: C
authors.initials: C
authors.lastname: Orikasa
authors.forename: Y
authors.initials: Y
authors.lastname: Sakuma
mesh_terms: D000367:Age Factors; D000679:Amygdala / Q000166:cytology / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001931:Brain Mapping; D002369:Castration; D047629:Estrogen Receptor beta / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000097:blood; D005260:Female; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000378:metabolism*; D011301:Preoptic Area / Q000166:cytology / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D014697:Ventromedial Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism*
chemical_list: D047629:Estrogen Receptor beta; D004967:Estrogens; D012333:RNA, Messenger