Neuroendocrine Control of Eel Puberty

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基本資料

Project title

Code/計畫編號

NSC98-2923-B019-001-MY3

Translated Name/計畫中文名

鰻魚青春期調控之神經內分泌機制

Project Coordinator/計畫主持人

Ching-Fong Chang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Aquaculture

Website

https://www.grb.gov.tw/search/planDetail?id=2213179

Year

2011

Start date/計畫起

01-01-2011

Expected Completion/計畫迄

31-12-2011

Bugetid/研究經費

2550千元

ResearchField/研究領域

漁業
海洋科學

"脊椎動物青春期，是繼胚胎發育之後另一重要發育階段，而且是該動物具有生殖能力之首要指標。在哺乳動物中，青春期是由促性腺激素軸線(gonadotropic axis)所啟動，此軸線由腦部的促性腺激素釋放素(gonadotropin-releasing hormone, GnRH)、腦下垂體的促性腺激素(gonadotropins, 包括黃體激素luteinising hormone, LH 和濾泡刺激素 follicle-stimulating hormone, FSH)，及性類固醇激素所組成。此外，近期之研究發現，腦神經肽之一的kisspeptin 也可能在青春期的啟發作用中扮演關鍵性的角色。在鰻魚Anguilla 屬中有15 種鰻魚在進行生殖迴游前，生長階段均停留在青春前期的階段。這種之生活史，使他們成為研究調控青春期啟動和停滯機制的絕佳模式動物。本研究計畫將在法國和台灣的合作架構下，針對兩地在生態和經濟上皆很重要的鰻魚，包括歐洲的歐洲鰻 (Anguilla anguilla)和亞洲的日本鰻(Anguilla japonica)進行研究。近十年來，因為過漁、污染和棲息地的破壞導致全世界的鰻苗資源皆急遽減少。在野外從未曾捕捉到成熟的鰻魚及撈獲鰻魚卵，此外，鰻魚在養殖環境下無法自然成熟，所以直到現在，養殖所需的鰻苗完全仰賴於沿岸捕撈之天然魚苗。這些資訊顯示培育鰻苗對水產養殖產業之急迫性。目前鰻魚人工繁殖，所採取的策略皆使用外源性的腦下垂體萃取物去刺激生殖腺的發育，但結果常會出現引發超出正常生理活動的類固醇生成作用，導致卵黃蓄積不當、卵質不佳等情形。為了避免這些問題，本研究計畫擬發展新的策略，針對brain-pituitary axis，激發其活性，促使內源性的促性腺激素生成及釋放，藉以刺激生殖腺的發育。我們的研究團隊近期之研究已證明，鰻魚由於缺乏GnRH 的刺激及dopamine (DA)的強烈抑制作用，導致腦下垂體gonadotropins 合成和釋放都不足，造成其青春期發育被阻斷。本研究計畫擬以鰻魚這種青春期被阻斷的模式動物為題材，探討導致青春期停滯的調控機制，發展新的分子生物學、藥理學和細胞學方面的新技術以釐清GnRH 和DA 對青春期啟動的神經內分泌調控機制，研究新的關鍵調控分子(例如：kisspeptin)，並發展誘導鰻魚性成熟的新策略。在分子生物學方面，將會建立GnRH 和 kisspeptin 等腦神經肽的基因選殖、即時定量PCR 等之技術，生產基因重組的DA D2 receptors 以應用於篩選DA 的拮抗物(建立新的藥理學工具以抵銷DA 的抑制作用)。細胞學方面包括建立腦及腦下垂體細胞培養。研究範疇包括野外和養殖場，活體和離體試驗等。Kiss、GnRH、DA 和 peripheral hormones 等對活化鰻魚腦下垂體gonadotropins 表現的交互作用將會採取離體方式進行實驗，結果再以活體進行驗證。鰻魚神經內分泌對青春期調控作用的新資料，將可對脊椎動物性成熟機制有更進一步的瞭解。對於鰻魚腦神經肽和receptors 的分子和功能上的研究亦可用於探源GnRH、DA 和 kisspeptin 系統在系統發生學上的關係。本計畫中所發展的分子生物學、藥理學和細胞學方面的新技術將可應用於基礎及應用科學領域。此外，本計畫針對鰻魚腦部生殖功能之深入研究，藉由本計畫研究調控鰻魚青春期之神經內分泌系統之成果，將可助於發展鰻魚繁殖新技術，將有助於鰻魚生態保育及鰻魚產業之永續發展。" "Puberty is a major event of the post-embryonic development in vertebrates and is defined as the first acquisition of the capacity to reproduce. In mammals, puberty is triggered by the activation of the gonadotropic axis, constituted of brain gonadotropin-releasing hormone (GnRH), pituitary gonadotropins (luteinising hormone, LH and follicle-stimulating hormone, FSH) and sex steroids. In addition, recent data highlighted the possible key-role of a brain neuropeptide, kisspeptin, in the pubertal activation of the gonadotropic axis. The fifteen species of genus Anguilla present the same striking life cycle, with a blockade at prepubertal stage before their reproductive migration. This makes them a remarkable model for investigating the mechanisms of blockade and triggering of puberty. This project will be developed in the frame of a french-taiwanese cooperation, on two species of major ecological concern and economical interest, the European (Anguilla anguilla) and the Asian (Anguilla japonica) eel species. In recent decades, populations of freshwater eels have declined dramatically around the world, mainly because of overfishing, pollution, and destruction of habitats (Stone, 2003). Mature adults have never been caught and eel eggs never collected in the wild. Moreover, eels do not mature naturally in captivity, and at present, eel farming completely relies on glass eels caught during their migration to the coasts. These data show the crucial need to breed eel in captivity. The actual protocols for experimental maturation are only based on gonadal stimulation with gonadotropic treatments, leading to extra-physiological activation of gonadal steroidogenesis, inadequate kinetic of vitellogenesis, inappropriate oocyte stores and poor quality eggs. In order to avoid these problems, the present project aims at developing new strategies by triggering the release of eel endogenous gonadotropins via the activation of brain-pituitary axis. This project focuses at analyzing the mechanisms which underly the occurrence of puberty in a unique model of puberty blockade. The tasks will aim at developing new molecular, pharmacological and cellular tools, in order to decipher regulatory mechanisms of the dual neuroendocrine control of puberty by GnRH and DA, to investigate new key-actors such as kisspeptin, and to develop new strategies to induce eel sexual maturation. Molecular tools (cloning and real-time PCR) for brain neuropeptides (GnRH, and kisspeptin) and their respective receptors, as well as for DA-D2 receptors will be developed. Production of eel recombinant DA D2 receptors (s) will allow the screening of specific antagonists (new pharmacological tools for counteracting DA inhibition). Cellular tools will include the set up of brain cell cultures and the use of pituitary cell cultures. Investigations will include field and farm studies, as well as in vitro and in vivo experiments. The interaction of Kiss, GnRH, DA, and peripheral hormones in the activation of eel pituitary gonadotropin expression will be investigated in vitro and validated in vivo. New data on the neuroendocrine control of puberty in eels, representative species of an ancient group of teleosts, will provide new insights on ancestral regulations of sexual maturation in vertebrates. Molecular and functional data on eel brain neuropeptides and receptors will contribute to retrace the phylogeny of GnRH, DA and kisspeptin systems. New molecular, cellular, and pharmacological tools developed in this project will be available for basic and applied sciences. In particular, advances in the characterization of eel brain control of reproduction will lead to new strategies to induce eel experimental maturation. Therefore the results should have a major impact on preservation of biodiversity, and development of sustainable eel-based economical activities."

Keyword(s)

鰻魚
生殖
青春期
神經內分泌
eel
reproductive endocrinology
puberty
brain-pituitary

DSpace CRIS

Neuroendocrine Control of Eel Puberty

基本資料

Description