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Stimulatory effects of insulin-like growth factor 1 on expression of gonadotropin subunit genes and release of follicle-stimulating hormone and luteinizing hormone in masu salmon pituitary cells early in gametogenesis

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Title: Stimulatory effects of insulin-like growth factor 1 on expression of gonadotropin subunit genes and release of follicle-stimulating hormone and luteinizing hormone in masu salmon pituitary cells early in gametogenesis
Authors: Furukuma, Shunji Browse this author
Onuma, Takeshi Browse this author
Swanson, Penny Browse this author
Luo, Qiong Browse this author
Koide, Nobuhisa Browse this author
Okada, Houji Browse this author
Urano, Akihisa Browse this author
Ando, Hironori Browse this author
Keywords: insulin-like growth factor 1
gonadotropin-releasing hormone
gonadotropin
pituitary
puberty
salmon
Issue Date: Jan-2008
Publisher: Zoological Society of Japan
Journal Title: Zoological Science
Volume: 25
Issue: 1
Start Page: 88
End Page: 98
Publisher DOI: 10.2108/zsj.25.88
Abstract: Insulin-like growth factor-I (IGF-I) has been shown to be involved in pubertal activation of gonadotropin (GTH) secretion. The aim of this study was to determine if IGF-I directly stimulates synthesis and release of GTH at an early stage of gametogenesis. The effects of IGF-I on expression of genes encoding glycoprotein α (GPα), follicle-stimulating hormone (FSH) β, and luteinizing hormone (LH) β subunits and release of FSH and LH were examined using primary pituitary cells of masu salmon at three reproductive stages: early gametogenesis, maturing stage, and spawning. IGF-I alone or IGF-I + salmon GnRH (sGnRH) were added to the primary pituitary cell cultures. Amounts of GPα, FSHβ, and LHβ mRNAs were determined by real-time PCR. Plasma and medium levels of FSH and LH were determined by RIA. In males, IGF-I increased the amounts of all three subunit mRNAs early in gametogenesis in a dose-dependent manner, but not in the later stages. In females, IGF-I stimulated release of FSH and LH early in gametogenesis, whereas no stimulatory effects on the subunit mRNA levels were observed at any stage. IGF-I + sGnRH stimulated release of FSH and LH at all stages in both sexes, but had different effects on the subunit mRNA levels depending on subunit and stage. The present results suggest that IGF-I itself directly stimulates synthesis and release of GTH early in gametogenesis in masu salmon, possibly acting as a metabolic signal that triggers the onset of puberty.
Type: article
URI: http://hdl.handle.net/2115/43960
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 浦野 明央

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