title: Sex-steroid receptor mechanism related to neuronal aromatase and the stigmoid body.
abstract: Recent immunohistochemical analyses of rat brains have established the presence of neuronal aromatase and stigmoid body in interfaces of a sex-steroid/brain axis. Aromatase P450-immunoreactive (AROM-I) neurons, which are present only during embryonic Day 16 to postnatal Day 2 (E16-P2), are found in the anterior medial preoptic nucleus, the periventricular preoptic nucleus, and the ventromedial hypothalamic nucleus. The largest AROM-I cell-group localized in the medial preoptico-amygdaloid neuronal arc (mPO-AM) shows a peak during E18-P2 and gradually diminishes after the perinatal days (but still retains the immunoreactivity in adults). In adults, other groups of AROM-I neurons emerge in the lateral septum, the central amygdaloid nucleus, and the bed nucleus of the stria terminalis. Male-predominant sex difference for aromatase expression has been detected at least in the young-to-adult mPO-AM, reflecting sexually distinct endocrine and behavioral responses in the rat reproductive functions. These results suggest the presence of distinct brain-aromatases with different regulatory systems. Neuronal aromatase may modulate development of sexual dimorphism in neonates and activation of reproductive functions in adults. The stigmoid bodies, marked by placental aromatase-associated antigen X-P2 (PAX) antiserum, are also frequent in the sex-steroid targets of rat brains and intimately coexist with estrogen receptors in the mPO-AM of young females. The neuronal inclusion, suspected as a RNA/protein conglomerate, appears to be induced by the decrease of androgen and/or the increase of estrogen, especially as a result of subneuronal aromatic switching into the estrogenous state. The neuronal aromatase and stigmoid body may play important roles in the pre- and post-receptor steps of subneuronal sex-steroids actions for brain sexual differentiation or induction of reproductive functions.
authors.affiliation: Department of Anatomy II, Kinki University School of Medicine, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shinoda
mesh_terms: D000679:Amygdala / Q000166:cytology*; D000818:Animals; D001141:Aromatase / Q000502:physiology*; D001931:Brain Mapping; D002454:Cell Differentiation / Q000502:physiology*; D005260:Female; D005865:Gestational Age; D007031:Hypothalamus / Q000166:cytology*; D002479:Inclusion Bodies / Q000648:ultrastructure*; D008297:Male; D009434:Neural Pathways / Q000166:cytology; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology; D011247:Pregnancy; D011301:Preoptic Area / Q000166:cytology; D051381:Rats; D011960:Receptors, Estrogen / Q000502:physiology*; D011980:Receptors, Progesterone / Q000502:physiology*; D012733:Sex Differentiation; D012741:Sexual Maturation / Q000502:physiology
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D001141:Aromatase