Estrogen regulates GFAP-expression in specific subnuclei of the female rat interpeduncular nucleus: a potential role for estrogen receptor beta.
We previously demonstrated that in rat, astrocytic glial fibrillary acidic protein- (GFAP) expression in the interpeduncular nucleus (IPN) was responsive to testosterone and in females the intensity of GFAP-immunoreactivity (IR) followed the periodic hormonal changes of the estrous cycle. The aim of this study was to test whether 17beta-estradiol (E(2)), in the absence of other ovarian hormones, can influence GFAP-expression within individual subnuclei of the IPN and to determine the cellular distribution of estrogen receptor beta (ERbeta) in the IPN. Quantitative surface-density analysis was used to compare the intensity of GFAP-IR at different anterio-posterior (AP) levels of the IPN in ovariectomized female rats 24 h after treatment with E(2) or vehicle. Estrogen-treatment resulted in a significant increase in GFAP-IR in the rostrolateral subnucleus of the IPN at AP: -5.60, in the lateral-, dorsolateral-, dorsomedial- and central subnuclei at -6.04 and in the lateral subnucleus at -6.72. No significant differences were observed at -5.80 and -6.30. These results indicate that E(2), in the absence of other ovarian hormones, modulates GFAP-expression within select IPN subnuclei and that these affects are dependent on position along the AP axis. To determine whether ERbeta was a possible mediator of the observed estrogenic effects, adjacent section pairs of the IPN were immunostained for ERbeta or GFAP. Using the 'mirror' method, ERbeta-IR was detected in the cytoplasm of GFAP-immunopositive astroglia and in the nuclei of GFAP-immunonegative neurons. These findings suggest that in the IPN, E(2) may directly modulate GFAP-expression through ERbeta-mediated mechanisms.
Zsarnovszky
Attila
A
Department of Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, 231 Albert Sabin Way, PO Box 670575, Cincinnati, OH 45267-0575, USA.
Smith
Todd
T
Hajos
Ferenc
F
Belcher
Scott M
SM
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D047629:Estrogen Receptor beta; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis / Q000096:biosynthesis*; D008636:Mesencephalon / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000032:analysis* / Q000502:physiology
D047629:Estrogen Receptor beta; D004967:Estrogens; D005904:Glial Fibrillary Acidic Protein; D011960:Receptors, Estrogen; D004958:Estradiol