title: Effects of ovariectomy and hypothalamic-pituitary disconnection on amounts of steroidogenic factor-1 mRNA in the ovine anterior pituitary gland.
abstract: Steroidogenic factor-1 (SF-1) is a transcription factor involved in regulation of steroidogenic enzymes. Recent evidence indicates that SF-1 is also important in the anterior pituitary gland, where it may influence gene expression in gonadotropes. We isolated a cDNA encoding ovine SF-1 and demonstrated that the SF-1 gene is expressed in the anterior pituitary gland of sheep. SF-1 transcripts and luteinizing hormone (LH) were colocalized in gonadotropes by in situ hybridization and immunohistochemistry, respectively. To test the hypothesis that GnRH stimulates pituitary expression of ovine SF-1 mRNA, ewes were ovariectomized to increase endogenous secretion of GnRH. Compared to ovary-intact ewes, ovariectomy resulted in three- and fourfold increases in steady-state amounts of mRNA encoding SF-1 and LH beta subunit, respectively. In ovariectomized ewes in which delivery of GnRH to the anterior pituitary gland was prevented by hypothalamic-pituitary disconnection (HPD), steady-state amounts of mRNA encoding SF-1 and LH beta-subunit were decreased. These results provide evidence that pituitary SF-1 gene expression in sheep is regulated by GnRH. Coordinate regulation of mRNAs encoding SF-1 and LH beta-subunit raises the possibility that SF-1 may be an important transcriptional regulator of LH beta-subunit gene expression in ovine gonadotropes.
authors.affiliation: Department of Physiology, Colorado State University, Fort Collins 80523, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Turzillo
authors.forename: C C
authors.initials: CC
authors.lastname: Quirk
authors.forename: J L
authors.initials: JL
authors.lastname: Juengel
authors.forename: T M
authors.initials: TM
authors.lastname: Nett
authors.forename: C M
authors.initials: CM
authors.lastname: Clay
mesh_terms: D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000235:genetics; D005260:Female; D051717:Fushi Tarazu Transcription Factors; D015870:Gene Expression; D018398:Homeodomain Proteins; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology / Q000601:surgery; D007106:Immune Sera / Q000276:immunology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007986:Luteinizing Hormone / Q000276:immunology; D010052:Ovariectomy; D010903:Pituitary Gland, Anterior / Q000737:chemistry* / Q000276:immunology / Q000601:surgery; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011817:Rabbits; D018160:Receptors, Cytoplasmic and Nuclear; D012756:Sheep; D054339:Steroidogenic Factor 1; D013997:Time Factors; D014157:Transcription Factors / Q000032:analysis* / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D007106:Immune Sera; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D007986:Luteinizing Hormone