Sex steroid-dependent regulatory mechanisms of reproductive and aggressive behaviors in fish

• Project/Area Number: 19H03044
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 40040:Aquatic life science-related
• Research Institution: The University of Tokyo
• Principal Investigator: Okubo Kataaki 東京大学, 大学院農学生命科学研究科(農学部), 教授 (10370131)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥17,160,000 (Direct Cost: ¥13,200,000、Indirect Cost: ¥3,960,000); Fiscal Year 2021: ¥5,850,000 (Direct Cost: ¥4,500,000、Indirect Cost: ¥1,350,000); Fiscal Year 2020: ¥6,760,000 (Direct Cost: ¥5,200,000、Indirect Cost: ¥1,560,000); Fiscal Year 2019: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
• Keywords: 性ホルモン / 魚類 / 生殖行動 / 攻撃行動

Outline of Research at the Start

魚類においては、「生殖行動の起こしやすさ」や「攻撃性の強さ」といった行動形質が、効率的な養殖の可否に直結する。これらの行動形質は生殖腺（卵巣あるいは精巣）から分泌される性ホルモンの支配下にあることが知られているが、脳に届いた性ホルモンが生殖行動や攻撃行動を引き起こす際に、脳内でどのような機構が作動するのかは明らかとなっていない。そこで本研究では、生殖行動や攻撃行動に顕著な異常を示す各種のメダカ変異体を用いて、この問いに回答を与えることを目指す。

Outline of Final Research Achievements

In vertebrates, including teleost fish, reproductive and aggressive behaviors are under the control of sex steroid hormones secreted from the ovaries and testes. In this study, we conducted a series of analyses in medaka to clarify "what brain mechanisms mediate the effects of sex steroid hormones on reproductive and aggressive behaviors in teleost fish". Our results showed, for example, that androgens stimulate the expression of the neuropeptide galanin in the preoptic area, which in turn triggers aggressive chases.

Academic Significance and Societal Importance of the Research Achievements

本研究により、雄性ホルモンが魚類の攻撃行動を引き起こす際の脳内メカニズムの一端が明らかとなった。今回明らかとなったのは、追い払い行動という攻撃行動の一要素を引き起こす脳内メカニズムに過ぎないが、研究をさらに進めることで、性ホルモンが生殖行動や攻撃行動を引き起こす際の脳内メカニズムの全容が見えてくることが期待される。そこで得られる成果は、基礎生物学的に価値があるだけでなく、水産増養殖への応用にもつながることが期待される。

Research Products

• [Journal Article] Estrogen mediates sex differences in preoptic neuropeptide and pituitary hormone production in medaka (2021)
  • Author(s): Yamashita J, Nishiike Y, Fleming T, Kayo D, Okubo K
  • Journal Title: Communications Biology Volume: 4 Issue: 1 Pages: 948-948
  • DOI: 10.1038/s42003-021-02476-5
  • Peer Reviewed / Open Access
• [Journal Article] Estrogen receptor 2b is the major determinant of sex-typical mating behavior and sexual preference in medaka (2021)
  • Author(s): Nishiike Yuji、Miyazoe Daichi、Togawa Rie、Yokoyama Keiko、Nakasone Kiyoshi、Miyata Masayoshi、Kikuchi Yukiko、Kamei Yasuhiro、Todo Takeshi、Ishikawa-Fujiwara Tomoko、Ohno Kaoru、Usami Takeshi、Nagahama Yoshitaka、Okubo Kataaki
  • Journal Title: Current Biology Volume: 31 Issue: 8 Pages: 1-12
  • DOI: 10.1016/j.cub.2021.01.089
  • Peer Reviewed / Open Access
• [Journal Article] Male-predominant galanin mediates androgen-dependent aggressive chases in medaka (2020)
  • Author(s): Yamashita Junpei、Takeuchi Akio、Hosono Kohei、Fleming Thomas、Nagahama Yoshitaka、Okubo Kataaki
  • Journal Title: eLife Volume: 9
  • DOI: 10.7554/elife.59470
  • Peer Reviewed / Open Access
• [Journal Article] Androgen-dependent sexual dimorphism in pituitary tryptophan hydroxylase expression: relevance to sex differences in pituitary hormones (2020)
  • Author(s): Kawabata-Sakata Yukika、Nishiike Yuji、Fleming Thomas、Kikuchi Yukiko、Okubo Kataaki
  • Journal Title: Proceedings of the Royal Society B: Biological Sciences Volume: 287 Issue: 1928 Pages: 20200713-20200713
  • DOI: 10.1098/rspb.2020.0713
  • Peer Reviewed
• [Journal Article] Neuropeptide B mediates female sexual receptivity in medaka fish, acting in a female-specific but reversible manner (2019)
  • Author(s): Hiraki-Kajiyama T, Yamashita J, Yokoyama K, Kikuchi Y, Nakajo M, Miyazoe D, Nishiike Y, Ishikawa K, Hosono K, Kawabata-Sakata Y, Ansai S, Kinoshita M, Nagahama Y, Okubo K
  • Journal Title: eLife Volume: 8
  • DOI: 10.7554/elife.39495
  • Peer Reviewed / Open Access
• [Presentation] How do evolutionarily conserved neural substrates give rise to variation in social behaviors across species? (2021)
  • Author(s): Okubo K
  • Organizer: Japan-Norway Symposium on Fish Endocrinology and Genomics
  • Int'l Joint Research / Invited
• [Presentation] Estrogen receptor 2b plays an essential role in establishing female mating behavior in medaka (2021)
  • Author(s): Nishiike Y, Okubo K
  • Organizer: Japan-Norway Symposium on Fish Endocrinology and Genomics
  • Int'l Joint Research
• [Presentation] Prostaglandin receptor 4b (ptger4b) regulates female receptivity in medaka (2021)
  • Author(s): Fleming T, Okubo K
  • Organizer: Japan-Norway Symposium on Fish Endocrinology and Genomics
  • Int'l Joint Research
• [Presentation] 性ステロイド環境に応じてメダカの性行動パターンをメス型化する脳内メカニズム (2021)
  • Author(s): 西池雄志、大久保範聡
  • Organizer: 第45回日本比較内分泌学会
• [Presentation] 魚類の性行動パターンの性差形成と性的可逆性 (2019)
  • Author(s): 大久保範聡
  • Organizer: 日本内分泌学会第37回内分泌代謝学サマーセミナー
  • Invited