title: Regulation of pituitary inhibin/activin subunits and follistatin gene expression by GnRH in female rats.
abstract: Pituitary inhibin B, activin B, and follistatin are local regulators of FSH. Activin B is a homodimeric molecule (β(B)-β(B)), while inhibin B contains an α and a β(B) subunit. The regulation of gene expression of α, β(B), and follistatin by local and endocrine hormones was examined in pituitaries from female rats and in perifused pituitary cells by RT-PCR. Ovariectomy (OVX) induced an elevation in the mRNA level of α and β(B) subunits and follistatin. Short-term (4 h) treatment of pituitary cells with GnRH decreased both the inhibin α and the inhibin/activin β(B) subunit mRNA levels, while long-term treatment (20 h) with 100 nM GnRH stimulated the expression of both subunits. In contrast, the mRNA level of follistatin was elevated after the short-term GnRH treatment. Long-term exposure of pituitary cells to estradiol and inhibin B suppressed the mRNA expression of β(B) and had no effect on the expression of α subunit and follistatin. Our results demonstrate that the increased expressions of inhibin/activin subunits and follistatin in the post-OVX period can be induced by the lack of gonadal negative feedback, resulting in a high GnRH environment in the pituitary. This study reports for the first time that GnRH administered in high doses and for a long period stimulates the gene expression of inhibin/activin subunits and thereby may contribute to the stimulatory effect of OVX on the expression of these genes.
authors.affiliation: Department of Anatomy, Medical School, University of Pecs, 12 Szigeti Street, Pecs 7624, Hungary.
authors.forename: Petra
authors.initials: P
authors.lastname: Popovics
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Rekasi
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Stewart
authors.forename: Magdolna
authors.initials: M
authors.lastname: Kovacs
mesh_terms: D028341:Activins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D004958:Estradiol / Q000378:metabolism; D005260:Female; D038681:Follistatin / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D028322:Inhibin-beta Subunits / Q000235:genetics / Q000378:metabolism; D007265:Inhibins / Q000235:genetics / Q000378:metabolism*; D010052:Ovariectomy / Q000009:adverse effects; D010902:Pituitary Gland / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011966:Receptors, LHRH / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D038681:Follistatin; C498906:Inhbb protein, rat; D021122:Protein Subunits; D012333:RNA, Messenger; D011966:Receptors, LHRH; C103008:inhibin beta A subunit; C094377:inhibin-alpha subunit; D028341:Activins; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007265:Inhibins; D028322:Inhibin-beta Subunits