| Project/Area Number |
15207007
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Morphology/Structure
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| Research Institution | Hiroshima University |
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Principal Investigator |
TSUTSUI Kazuyoshi Hiroshima University, Graduate School of Integrate Arts and Sciences, Professor, 大学院総合科学研究科, 教授 (20163842)
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| Co-Investigator(Kenkyū-buntansha) |
KIKUYAMA Sakae Waseda University, Faculty of Education, Professor, 教育総合科学学術院, 教授 (20063638)
MINAKATA Hiroyuki Suntory Institute for Bioorganic Research, General Manager, 部長研究員 (90150143)
UKENA Kazuyoshi Graduate School of Integrate Arts and Sciences, Associate Professor, 大学院総合科学研究科, 助教授 (10304370)
TAKAHASHI Toshio Suntory Institute for Bioorganic Research, Researcher, 研究員 (20390792)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥40,040,000 (Direct Cost: ¥30,800,000、Indirect Cost: ¥9,240,000)
Fiscal Year 2005: ¥8,840,000 (Direct Cost: ¥6,800,000、Indirect Cost: ¥2,040,000)
Fiscal Year 2004: ¥15,600,000 (Direct Cost: ¥12,000,000、Indirect Cost: ¥3,600,000)
Fiscal Year 2003: ¥15,600,000 (Direct Cost: ¥12,000,000、Indirect Cost: ¥3,600,000)
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| Keywords | hypothalamic neurohormones / GnIH / GnIH homologOus peptides / GnIH receptor / pituitary hormones / gonadotropin / prolactin / reproduction / 生殖腺刺激ホルモン放出抑制ホルモン(GnIH) / 視床下部ニューロン / メラトニン / 新規視床下部ペプチド / ゴナドトロピン / 成長ホルモン / ゴナドトロピン放出抑制ホルモン / 成長ホルモン放出促進ペプチド / 新規視床下部ペプチド受容体 |
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| Research Abstract |
Probing undiscovered neuropeptides that play important roles in the regulation of pituitary function in vertebrates is essential for the progress of neuroendocrinology. In this research, We identified a novel hypothalamic neuropeptide with a C-terminal LPLRF-amide sequence in the quail brain. This avian neuropeptide was, shown to be located in the hypothalamo-hypophysial system and to decrease gonadotropin release. We therefore designated this novel neuropeptide as gonadotropin-inhibitory hormone (GnIH). To elucidate the mode of action of GnIH, we then' identified a novel G protein:-coupled receptor for GnIH in quail. The GnIH receptor possesses seven transmembrane domains and specifically binds to GnIH. The GnIH receptor is expressed in the pituitary and several brain regions including the hypothalamus. Thus, GnIH acts directly on the pituitary via GnIH receptor to inhibit gonadotropin release. To demonstrate the functional significance of GnIH and its potential role as a key regulatory neuropeptide in avian reproduction, we investigated GnIH actions on gonadal development and maintenance in quail. Chronic treatment with GnIH inhibited gonadal development and maintenance by decreasing gonadotropin synthesis and release. GnIH was also found in the hypothalamus of other avian species including sparrows and chickens and also inhibited gonadotropin synthesis and release. Subsequently, we further identified novel hypothalamic neuropeptides closely related to GnIH in the brains of other vertebrates, such as mammals, amphibians, and fish. The identified neuropeptides possessed a LPXRF-amide (X = L or Q) motif at 'their C-termini. These GnIH homologous peptides (LPXRF-amide peptides) also were localized in the hypothalamus and other brainstem areas and regulated the release of gonadotropins and prolactin. Thus, GnIH and GnIH homologous peptides are key factors controlling vertebrate reproduction.
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