title: Expression and distribution of P450-aromatase in the ovine hypothalamus at different stages of fetal development.
abstract: OBJECTIVE
  An important step of sexual differentiation is the conversion of testosterone to estrogen by aromatase leading to masculinization and defeminization of the fetal brain areas crucial for normal sexual behavior and reproduction. Brain sexual differentiation occurs throughout a critical period starting from different prenatal stages depending on the species. Such period goes on from gestation day (GD) 30 to 100GD in the sheep. The fetal sheep brain is reported to aromatize androgens to estrogens at 64GD. The main goal of this work was to evaluate aromatase expression in sheep hypothalami during the whole period of sexual differentiation (35GD, 55GD, 80GD, 115GD) and whether differences may be observed depending on gestational stage and sex.
  
  
  METHODS
  Sections at the hypothalamic level underwent immunoperoxidase technique employing anti-aromatase and anti-androgen receptor antibodies. Samples from 35GD and 55GD were also processed with in situ hybridization using aromatase cDNA probe. Blot analyses were performed to quantify possible aromatase immunoexpression differences between sexes. For sexing, samples at 35GD and 55GD underwent DNA extraction and SRY amplification.
  
  
  RESULTS
  Our results revealed aromatase and androgen receptor immunoreactivity along the whole period of sexual differentiation. Both molecules were detected in many brain regions and markedly in the periventricular area. The highest aromatase and androgen receptor amounts were observed at 35GD and 55GD, when aromatase was more abundant in females than in males.
  
  
  CONCLUSIONS
  In conclusion, the sheep can be included among the species where aromatase is highly expressed in the hypothalamus during the whole period of sexual differentiation.
authors.affiliation: Department of Animal Biology, University of Sassari, Italy. armura@uniss.it
authors.forename: Arcadia
authors.initials: A
authors.lastname: Mura
authors.forename: Sergio
authors.initials: S
authors.lastname: Gadau
authors.forename: Gianluca
authors.initials: G
authors.lastname: Lepore
authors.forename: Francesca
authors.initials: F
authors.lastname: Balzano
authors.forename: Marco
authors.initials: M
authors.lastname: Zedda
authors.forename: Emilio
authors.initials: E
authors.lastname: Mura
authors.forename: Vittorio
authors.initials: V
authors.lastname: Farina
mesh_terms: D000367:Age Factors; D000818:Animals; D001141:Aromatase / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000378:metabolism; D005260:Female; D047109:Fetal Development / Q000235:genetics / Q000502:physiology*; D005333:Fetus / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D005865:Gestational Age; D007031:Hypothalamus / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D011247:Pregnancy; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D012733:Sex Differentiation / Q000235:genetics / Q000502:physiology*; D012737:Sex Factors; D012756:Sheep / Q000254:growth & development* / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D011944:Receptors, Androgen; D001141:Aromatase