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Changes in the plasma levels of insulin-like growth factor-I from the onset of spawning migration through upstream migration in chum salmon

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Title: Changes in the plasma levels of insulin-like growth factor-I from the onset of spawning migration through upstream migration in chum salmon
Authors: Onuma, Takeshi A. Browse this author
Makino, Keita Browse this author
Katsumata, Hiroshi Browse this author
Beckman, Brian R. Browse this author
Ban, Masatoshi Browse this author
Ando, Hironori Browse this author
Fukuwaka, Masa-aki Browse this author
Azumaya, Tomonori Browse this author
Swanson, Penny Browse this author
Urano, Akihisa Browse this author
Keywords: Spawning migration
Chum salmon
Growth
IGF-I
Liver
Gonad
Gonadotropin
Androgen
Estrogen
Pituitary-gonadal axis
Issue Date: 15-Jan-2010
Publisher: Elsevier
Journal Title: General and Comparative Endocrinology
Volume: 165
Issue: 2
Start Page: 237
End Page: 243
Publisher DOI: 10.1016/j.ygcen.2009.07.005
Abstract: An increase in activity of the pituitary-gonadal axis (PG-axis) and gonadal development are essential for the onset of spawning migration of chum salmon from the Bering Sea. In the Bering Sea, fish with larger body sizes initiated gonadal development and commenced spawning migration to the natal river by the end of summer. We thus hypothesized that insulin-like growth factor-I (IGF-I), a somatotropic signal that interacts with the PG-axis, can be one of such factors responsible for the onset of migration, and examined changes in plasma levels and hepatic expression of IGF-I gene in oceanic and homing chum salmon in 2001, 2002 and 2003. The plasma IGF-I levels and corresponding body sizes in maturing adults, which had developing gonads, were significantly higher than those in immature fish in all years examined. Such increase in the plasma IGF-I levels in maturing fish was observed even in the Gulf of Alaska during February 2006, while coincident increase was not observed in the hepatic amounts of IGF-I mRNA. In autumn, the plasma IGF-I levels in homing adults decreased during upstream migration in the Ishikari River-Ishikari bay water system in Hokkaido, Japan. In conclusion, the plasma IGF-I levels increased with gonadal development when chum salmon migrated from the winter Gulf of Alaska to the summer Bering Sea. Circulating IGF-I may interact with the PG-axis and promote gonadal development that is inseparable from the onset of spawning migration. Circulating IGF-I levels were thereafter lowered in accordance with final maturation during upstream migration in the breeding season.
Type: article (author version)
URI: http://hdl.handle.net/2115/42619
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 浦野 明央

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