Incomplete Development of the Brain-Pituitary-Gonadal Axis May Underlie the Delay in the Initiation of Precocious Maturation in Male Sockeye Salmon

• Amano Masafumi

  Nikko Branch, National Research Institute of Aquaculture School of Fisheries Sciences, Kitasato University

• Okumoto Naoto

  Nikko Branch, National Research Institute of Aquaculture

• Aida Katsumi

  Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo

書誌事項

タイトル別名

• Incomplete Development of the Brain-Pit

抄録

Precocious males first appear in the second year in sockeye salmon, whereas in masu salmon they appear in the first year. In underyearling male masu salmon, precocious maturation is accelerated under short photoperiod with an increase in salmon gonadotropin-releasing hormone (sGnRH) and pituitary gonadotropin subunit (GTH Iβ and GTH IIβ) contents, suggesting that the brain-pituitary-gonadal axis is already completed. In this study, the development of the brain-pituitary-gonadal axis in underyearling male sockeye salmon was investigated by manipulating photoperiod in order to clarify the relationship between its development and initiation of precocious maturation. Fish were divided into short (8L-16D) and long photoperiodic (16L-8D) groups in June and were reared for 4 months until October. sGnRH contents in the brain and pituitary, and GTH Iβ and GTH IIβ contents in the pituitary were measured. sGnRH contents in the hypothalamus and the pituitary, and GTH Iβ contents in the pituitary increased under short photoperiod, although gonadal maturation was notinduced under either photoperiod. However, pituitary GTH IIβ contents did not increase in either photoperiodic group. These results suggest that in contrast to masu salmon, the brain-pituitary-gonadal axis is not completed in underyearling male sockeye salmon. This species-specific difference in the development of the brain-pituitary-gonadal axis may underlie differences in the initiation of precocious maturation.

収録刊行物

• Ｆｉｓｈｅｒｉｅｓ　ｓｃｉｅｎｃｅ

  Ｆｉｓｈｅｒｉｅｓ　ｓｃｉｅｎｃｅ 63 (6), 873-876, 1997

  公益社団法人 日本水産学会

キーワード

• precocious
• salmon GnRH
• GTH
• sockeye salmon

詳細情報

• CRID: 1390282679405654656
• NII論文ID: 130003903130
• NII論文ID: 10004872048
• NII書誌ID: AA10993718
• DOI: 10.2331/fishsci.63.873
• NDL書誌ID: 4371609
• ISSN: 09199268
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I4371609
• Web Site: https://www.jstage.jst.go.jp/article/fishsci1994/63/6/63_6_873/_pdf
• 本文言語コード: en
• データソース種別:
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  • NDL
  • Crossref
  • CiNii Articles
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