1993 Fiscal Year Final Research Report Summary
REGULATORY MECHANISMS OF REPRODUCTIVE RHYTHMS IN FISHES
| Project/Area Number |
03404010
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | The University of Tokyo |
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Principal Investigator |
AIDA Katsumi The University of Tokyo, Faculty of Agriculture, Professor, 農学部, 教授 (50012034)
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| Co-Investigator(Kenkyū-buntansha) |
ASAHINA Kiyoshi Nippon University, College of Agriculture and Veterinary Medicine, Associate Pro, 農獣医学部, 助教授 (10147671)
OKA Yoshitaka The University of Tokyo, Faculty of Science, Assistant Professor, 理学部, 助手 (70143360)
KUBOKAWA Kaoru The University of Tokyo, Ocean Research Institute, Assistant Professor, 海洋研究所, 助手 (30240740)
FURUKAWA Kiyoshi The University of Tokyo, Faculty of Agriculture, Assistant Professor, 農学部, 助手 (40134514)
KOBAYASHI Makito The University of Tokyo, Faculty of Agriculture, Assistant Professor, 農学部, 助手 (30183809)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Reproductive rhythm / Teleost / Ovulation / Spawning / GnRH / Gonadotropin / Melatonin / Circadian rhythm |
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| Research Abstract |
Regulatory mechanisms of the reproductive rhythm (annual reproductive rhythm and spawning rhythm) in fishes were elucidated in this investigation. The summary of the results is as follows.
1. Reproductive rhythm and its control
(1) Annual reproductive rhythm, (2) Spawning rhythm, (3) Induction of spawning by hormone administration
2. Gonadotropin-releasing hormone (GnRH)
(1) Immunocytochemistry of GnRH cells and identification of GnRH,(2) Changes following gonadal matuation (3) Function of terminal nerve GnRH cells, (4) Structure and expression of GnRH gene
3. Structure and Function of gonadotropin
4. Melatonin rhythm
GnRH cells were found in the olfactory bulbs (terminal nerve), the ventral area of the telencephalon and the preoptic area. GnRH cells in the telencephalon and the preoptic area were involved in the regulation of reproduction, but GnRH cells in the olfactory bulbs were not involved. GnRH from the terminal nerve was widely distributed in the brain, and was suggested to function as a neuromodulator. In the masu salmon, number of GnRH cells in the ventral telencephalon and the preoptic area rapidly increased with the development of the testis when the dayllength was shortened. This result indicates that photoperiodic information regulates the annual reproductive rhythm via GnRH synthesis and release. It was also ascertained that the pineal gland possesses biological clock. Spawning time was determined by the photopepriodic cue, and the onset of the rhythm was light-on in the sirogisu, and light off in the tobinumeri-dragonet.
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