title: Development of a homologous radioimmunoassay for red seabream follicle stimulating hormone and regulation of gonadotropins by GnRH in red seabream, Pagrus major.
abstract: Using a recombinant chimeric single-chain follicle stimulating hormone (FSH), we established a radioimmunoassay (RIA) for red seabream (Pagrus major) FSH (pmFSH) which became a powerful tool for studying reproductive physiology. We studied the profiles in plasma and pituitary concentrations of FSH and luteinizing hormone (LH) during sexual maturation. A pre-established RIA for red seabream LH was used for the LH measurements. The regulation of FSH and LH secretion from the pituitary was investigated using a gonadotropin-releasing hormone analog (GnRHa) in vivo and in vitro. Marked differences in plasma and pituitary FSH levels were observed between males and females; pituitary FSH content in males was much higher than that in females during all seasons, and plasma FSH levels in males were high during the spawning season, whereas those in females were unchanged. In contrast, plasma and pituitary levels of LH were elevated before and during the spawning season in males and females. Injecting or implanting (cholesterol pellet) a GnRHa into adult and juvenile red seabream resulted in significant increases in plasma LH concentrations; however, no significant change was observed in plasma FSH. Moreover, GnRHa stimulated only LH secretion in an in vitro experiment using dispersed pituitary cells. The discrete FSH and LH secretion profiles revealed suggest differential roles for the two gonadotropins during red seabream gametogenesis. In addition, the marked difference in pituitary FSH levels in males and females suggests the relative significance of FSH in male reproduction.
authors.affiliation: Kamiura Laboratory, National Research Institute of Aquaculture, Fisheries Research Agency, Tsuiura, Kamiura, Saiki, Oita 879-2602 , Japan. Electronic address: kokuzawa@fra.affrc.go.jp.
authors.forename: Koichi
authors.initials: K
authors.lastname: Okuzawa
authors.affiliation: Kamiura Laboratory, National Research Institute of Aquaculture, Fisheries Research Agency, Tsuiura, Kamiura, Saiki, Oita 879-2602 , Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Kazeto
authors.affiliation: National Research Institute of Aquaculture, Fisheries Research Agency, 422-1 Nakatsuhamaura, Minami-ise, Watarai, Mie 516-0193, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Uji
authors.affiliation: Kamiura Laboratory, National Research Institute of Aquaculture, Fisheries Research Agency, Tsuiura, Kamiura, Saiki, Oita 879-2602 , Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: National Research Institute of Aquaculture, Fisheries Research Agency, 422-1 Nakatsuhamaura, Minami-ise, Watarai, Mie 516-0193, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: National Research Institute of Fisheries Science, Fisheries Research Agency, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan.
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Nyuji
authors.affiliation: Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira-cho, Nagasaki, Nagasaki 851-2213, Japan.
authors.forename: Koichiro
authors.initials: K
authors.lastname: Gen
mesh_terms: D000818:Animals; D005260:Female; D005640:Follicle Stimulating Hormone / Q000032:analysis* / Q000097:blood; D005718:Gametogenesis / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology*; D006062:Gonadotropins / Q000032:analysis* / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000032:analysis / Q000097:blood; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism; D011863:Radioimmunoassay / Q000379:methods; D021541:Sea Bream / Q000378:metabolism* / Q000502:physiology; D012621:Seasons; D012741:Sexual Maturation / Q000502:physiology
chemical_list: D006062:Gonadotropins; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone
keywords: FSH; GnRHa; LH; RIA; Red seabream; Seasonal change