Transient transcription of the somatostatin gene at the time of estrogen-dependent organization of the sexually dimorphic nucleus of the rat preoptic area.
In situ hybridization detected a transient, sex-specific transcription of somatostatin gene in the central part of the rat medial preoptic nucleus, which coincides with the sexually dimorphic nucleus of the preoptic area (SDN-POA), during, but not after, the establishment of sex difference. On postnatal d 1 (day of birth), somatostatin mRNA was detected in the SDN-POA of both sexes. On d 8 through 35, the area of somatostatin mRNA-positive cells was significantly larger in males than in females. In males the area attained its maximum size on d 15 and diminished gradually thereafter. In females the area did not change in size during this period. On d 60 expression of somatostatin mRNA was low and not different between sexes. Throughout the observed period, Nissl staining and calbindin immunohistochemistry enabled visualization of the typical SDN-POA in the same region. As with Nissl staining and calbindin immunohistochemistry, somatostatin mRNA hybridization on d 15 revealed a reversal of the sexual dimorphism in the size of the SDN-POA in males that had been neonatally orchidectomized or females given estrogen as pups, showing that sex steroid milieu during the organizational period determines the area occupied by somatostatin mRNA-positive cells. Sex-specific, transient transcription of the somatostatin gene may causally relate to the estrogen-dependent organization of the SDN-POA.
Orikasa
Chitose
C
Department of Physiology, Nippon Medical School, Sendagi 1, Bunkyo, Tokyo 113-8602, Japan. orikasa@nms.ac.jp
Kondo
Yasuhiko
Y
Sakuma
Yasuo
Y
D000818:Animals; D000831:Animals, Newborn; D064026:Calbindins; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D008297:Male; D011247:Pregnancy; D011301:Preoptic Area / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D012727:Sex Characteristics; D013004:Somatostatin / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic
D064026:Calbindins; D004967:Estrogens; D012333:RNA, Messenger; D064030:S100 Calcium Binding Protein G; D013004:Somatostatin