title: Gonadal steroid action and brain sex differentiation in the rat.
abstract: Gonadal steroids that establish sexually dimorphic characteristics of brain morphology and physiology act at a particular stage of ontogeny. Testosterone secreted by the testes during late gestational and neonatal periods causes significant brain sexual dimorphism in the rat. This results in both sex-specific behaviour and endocrinology in adults. Sexual differentiation may be due to neurogenesis, migration or survival. Each mechanism appears to be uniquely regulated in a site-specific manner. Thus, the volume of an aggregate of neurones in the rat medial preoptic area (POA), termed the sexually dimorphic nucleus of the POA (SDN-POA), is larger in males than in females. The anteroventral periventricular nucleus (AVPV) is packed with neurones containing oestrogen receptor (ER)beta in female rats but, in males, ERbeta-positive neurones scatter into the more lateral portion of the POA. POA neurones are born up to embryonic days 16-17 and not after parturition. Therefore, neurogenesis is unlikely to contribute to the larger SDN-POA in males. DNA microarray analysis for oestrogen-responsive genes and western blotting demonstrated site-specific regulation of apoptosis- and migration-related genes in the SDN-POA and AVPV.
authors.affiliation: Department of Physiology, Nippon Medical School, Tokyo, Japan. ysakuma@nms.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Sakuma
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology*; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D047629:Estrogen Receptor beta / Q000378:metabolism; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D008297:Male; D055495:Neurogenesis / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009929:Organ Size; D011301:Preoptic Area / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D051381:Rats; D012727:Sex Characteristics; D012733:Sex Differentiation / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism
chemical_list: D047629:Estrogen Receptor beta; D012739:Gonadal Steroid Hormones; D013739:Testosterone