Estrogen receptor-beta immunoreactivity in luteinizing hormone-releasing hormone neurons of the rat brain.
Feedback regulation of luteinizing hormone-releasing hormone (LHRH) neurons by estradiol plays important roles in the neuroendocrine control of reproduction. Recently, we found that the majority of LHRH neurons in the rat contain estrogen receptor-beta (ER-beta) mRNA, whereas, they seemed to lack ER-alpha mRNA expression. In addition, we observed nuclear uptake of (125)I-estrogen by a subset of these cells. These data suggest that ER-beta is the chief receptor isoform mediating direct estrogen effects upon LHRH neurons. To verify the translation of ER-beta protein within LHRH cells, the present studies applied dual-label immunocytochemistry (ICC) to free-floating sections obtained from the preoptic area of rats. The improved ICC method using the silver-gold intensification of nickel-diaminobenzidine chromogen, enabled the observation of nuclear ER-beta-immunoreactivity in the majority of LHRH cells. The incidence of ER-beta expression was similarly high in LHRH neurons of ovariectomized female (87.8 +/- 2.3%, mean +/- SEM), estradiol-primed female (74.9 +/- 3.2%) and intact male (85.0 +/- 4.7%) rats. The presence of ER-beta mRNA, ER-beta immunoreactivity and (125)I-estrogen binding sites in LHRH neurons of the rat provide strong support for the notion that these cells are directly regulated by estradiol, through ER-beta. The gene targets and molecular mechanisms of this regulation remain unknown.
Hrabovszky
E
E
Department of Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, 1083 Hungary.
Steinhauser
A
A
Barabás
K
K
Shughrue
P J
PJ
Petersen
S L
SL
Merchenthaler
I
I
Liposits
Z
Z
D000818:Animals; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D047629:Estrogen Receptor beta; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010052:Ovariectomy; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*
D047629:Estrogen Receptor beta; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol