title: Expression of estrogen receptor in the facial nucleus is suppressed by estradiol, but not by testosterone, indicating a lack of requirement for aromatization.
abstract: The transient expression of estrogen receptor (ER) in the ventromedial subnucleus of the facial nucleus was previously detected in the newborn rat, and the expression of ER molecules was down-regulated by daily injections of estradiol. Here we examined possible involvement of aromatization in this process. ER molecules were measured by immunohistochemistry and in situ hybridization histochemistry after daily injections of testosterone propionate (TP; 100 micrograms/0.02 ml) and estradiol benzoate (EB; 10 micrograms/0.02 ml) in the male pups castrated within 24 h of birth. Daily injections of TP for 5 consecutive days did not suppress ER and ER mRNA in the facial nucleus, while they were both suppressed by daily injections of EB. Moreover, aromatase immunoreactivity was not detected in the facial nucleus of both castrated, TP injected and intact control males at 6 days of age. The present findings therefore suggest that ER molecules expressed transiently in the facial nucleus are not directly involved in masculine sexual differentiation of the brain in newborn rat.
authors.affiliation: Department of Physiology I, Nippon Medical School, Tokyo, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Orikasa
authors.forename: M
authors.initials: M
authors.lastname: Yokosuka
authors.forename: S
authors.initials: S
authors.lastname: Hayashi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001141:Aromatase / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D005154:Facial Nerve / Q000737:chemistry / Q000166:cytology / Q000201:enzymology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry / Q000201:enzymology / Q000648:ultrastructure*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000096:biosynthesis* / Q000235:genetics; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D011960:Receptors, Estrogen; D013739:Testosterone; D004958:Estradiol; D001141:Aromatase