Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 873
Title: Postprandial changes in plasma growth hormone, insulin, insulin-like growth factor (IGF)-I and IGF-binding proteins in coho salmon (Oncorhynchus kisutch) fasted for varying periods
Author: M. Shimizu, K. A. Cooper, Walton W. Dickhoff, Brian R. Beckman
Publication Year: 2009
Journal: American Journal of Physiology
Volume: 297
Pages: R352-361
DOI: 10.1152/ajpregu.90939.2008
Keywords: postprandial change, growth hormone, insulin, insulin-like growth factor (IGF)-I, IGF-binding protein, salmon
Abstract: Postprandial changes in plasma growth hormone, insulin, insulin-like growth factor (IGF)-I, and IGF-binding proteins in coho salmon fasted for varying periods. Am J Physiol Regul Integr Comp Physiol 297: R352R361, 2009. First published May 27, 2009; doi:10.1152/ajpregu.90939.2008.We examined postprandial changes in circulating growth hormone (GH), insulin, insulin-like growth factor (IGF)-I, and IGF-binding proteins (IGFBPs) in yearling coho salmon under different feeding regimes. Fish were initially fasted for 1 day, 1 wk, or 3 wk. Fasted fish were then fed, and blood was collected at 4-h intervals over 26 h. After the various periods of fasting, basal levels of insulin were relatively constant, whereas those of IGF-I, IGFBPs and GH changed in proportion to the duration of the fast. A single meal caused a rapid, large increase in the circulating insulin levels, but the degree of the increase was influenced by the fasting period. IGF-I showed a moderate increase 2 h after the meal but only in the regularly fed fish. Plasma levels of 41-kDa IGFBP were increased in all groups within 6 h after the single meal. The fasting period did not influence the response of 41-kDa IGFBP to the meal. IGFBP-1 and GH decreased after the meal to the same extent among groups regardless of the fasting period. The present study shows that insulin and IGF-I respond differently to long (weeks)- and short (hours)-term nutritional changes in salmon; insulin maintains its basal level but changes acutely in response to food intake, whereas IGF-I adjusts its basal levels to the long-term nutritional status and is less responsive to acute nutritional input. IGFBPs maintain their sensitivity to food intake, even after prolonged fasting, suggesting their
Official Citation: Shimizu, M., K.A. Cooper, W.W. Dickhoff, and B.R. Beckman. 2009. Postprandial changes in plasma growth hormone, insulin, insulin-like growth factor (IGF)-I and IGF-binding proteins in coho salmon fasted for varying periods. Am. J. Physiol. Regul. Integr. Comp. Physiol 297:R352-361.