title: Estrogen regulates the localization and expression of calbindin-D9k in the pituitary gland of immature male rats via the ERalpha-pathway.
abstract: Estrogen (E2; estradiol) plays a key role in the regulation of many pituitary hormones. It exerts its effects by binding to the intracellular estrogen receptor (ER), which then functions as a transcription factor. Although E2 has been shown to regulate calbindin-D(9k) (CaBP-9k) in the female reproductive system of rodents, the effects of E2 on the regulation of CaBP-9k in male rats remain to be elucidated. To investigate E2-induced regulation of the pituitary CaBP-9k gene, immature male rats were injected with E2 daily for 3 consecutive days with a dose of 40 microg/kg body weight (BW). The expression levels of CaBP-9k mRNA and protein were analyzed by RT-PCR and Western blot analysis, respectively, in the absence and presence of ICI 182,780 (ICI), an E2 antagonist. In addition, the tissue localization of CaBP-9k was determined by immunohistochemistry. CaBP-9k was localized in the cytoplasm of a specific cell type (acidophils) in the anterior lobe of the pituitary gland and highly expressed in the intermediate lobe. Exposure to E2 increased the number of cells that stained positive for CaBP-9k. To determine which ER subtype is involved in CaBP-9k regulation in the pituitary, the immature rats were treated with propyl pyrazole triol (PPT, an ERalpha-selective ligand) or diarylpropionitrile (DPN, an ERbeta-selective ligand) for 3 days. Pituitary CaBP-9k expression was mainly mediated by PPT in immature male rats, whereas no significant alteration of pituitary CaBP-9k gene expression was observed after DPN treatment. In addition, the estrogenicity of PPT in the induction of CaBP-9k expression was completely blocked by an estrogen antagonist, ICI, indicating that pituitary CaBP-9k expression is solely induced by ERalpha. Taken together, these results suggest that pituitary CaBP-9k is induced by E2 in male rats and its expression is predominantly regulated by ERalpha, but not ERbeta.
authors.affiliation: Laboratory of Veterinary Biochemistry and Molecular Biology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea.
authors.forename: Pushpalatha
authors.initials: P
authors.lastname: Tinnanooru
authors.forename: Vu Hoang
authors.initials: VH
authors.lastname: Dang
authors.forename: Thi Hoa
authors.initials: TH
authors.lastname: Nguyen
authors.forename: Geun-Shik
authors.initials: GS
authors.lastname: Lee
authors.forename: Kyung-Chul
authors.initials: KC
authors.lastname: Choi
authors.forename: Eui-Bae
authors.initials: EB
authors.lastname: Jeung
mesh_terms: D000818:Animals; D064026:Calbindins; D004958:Estradiol / Q000031:analogs & derivatives / Q000378:metabolism; D004965:Estrogen Antagonists / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D000077267:Fulvestrant; D005786:Gene Expression Regulation; D008297:Male; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D064026:Calbindins; D004965:Estrogen Antagonists; D047628:Estrogen Receptor alpha; D004967:Estrogens; D064030:S100 Calcium Binding Protein G; C576508:S100g protein, rat; D000077267:Fulvestrant; D004958:Estradiol