Document Detail

Disruption of seasonality in growth hormone-transgenic coho salmon (Oncorhynchus kisutch) and the role of cholecystokinin in seasonal feeding behavior.
MedLine Citation:
PMID:  18667200     Owner:  NLM     Status:  MEDLINE    
Seasonal variation in daily food intake is a well-documented phenomenon in many organisms including wild-type coho salmon where the appetite is noticeably reduced during periods of decreased day length and low water temperature. This reduction may in part be explained by altered production of cholecystokinin (CCK) and growth hormone (GH). CCK is a hormone produced in the brain and gut that mediates a feeling of satiety and thus has an inhibitory effect on food intake and foraging behaviour. Growth hormone (GH) enhances feeding behaviour and consequently growth, but its production is reduced during winter. The objectives of this study were: first, to compare the seasonal feeding behaviour of wild and GH-transgenic coho salmon; second, to determine the behavioural effect of blocking the action of CCK (by using devazepide) on the seasonal food intake; and third, to measure CCK expression in brain and gut tissues between the two genotypes across seasons. We found that, in contrast to wild salmon, food intake in transgenic salmon was not reduced during winter indicating that seasonal control of appetite regulation has been disrupted by constitutive production of GH in transgenic animals. Blocking of CCK increased food intake in both genotypes in all seasons. The increase was stronger in wild genotypes than transgenic fish; however blocking CCK in wild-type fish in winter did not elevate appetites to levels observed in the summer. The response to devazepide was generally faster in transgenic than in wild salmon with more rapid effects observed during summer than during winter, possibly due to a higher temperature in summer. Overall, a seasonal effect on CCK mRNA levels was observed in telencephalon with levels during winter being higher compared to the summer in wild fish, but with no seasonal effect in transgenic fish. No differences in seasonal CCK expression were found in hypothalamus. Higher levels of CCK were detected in the gut of both genotypes in winter compared to summer. Thus, CCK appears to mediate food intake among seasons in both wild-type and GH-transgenic salmon, and an altered CCK regulation may be responsible at least in part for the seasonal regulation of food intake.
Mare Lõhmus; Peter A Raven; L Fredrik Sundström; Robert H Devlin
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-03-10
Journal Detail:
Title:  Hormones and behavior     Volume:  54     ISSN:  1095-6867     ISO Abbreviation:  Horm Behav     Publication Date:  2008 Sep 
Date Detail:
Created Date:  2008-08-29     Completed Date:  2008-11-12     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0217764     Medline TA:  Horm Behav     Country:  United States    
Other Details:
Languages:  eng     Pagination:  506-13     Citation Subset:  IM    
Fisheries and Oceans Canada, Centre for Aquaculture and Environmental Research, 4160 Marine Drive, West Vancouver, V7V 1N6, BC Canada.
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MeSH Terms
Animals, Genetically Modified
Appetite Regulation / drug effects,  genetics
Behavior, Animal / drug effects,  physiology
Brain / metabolism
Cholecystokinin / antagonists & inhibitors,  genetics,  metabolism,  physiology*
Devazepide / pharmacology
Feeding Behavior / drug effects,  physiology*
Growth Hormone / genetics*
Hormone Antagonists / pharmacology
Intestines / metabolism
Oncorhynchus kisutch / genetics*,  physiology*
Reg. No./Substance:
0/Hormone Antagonists; 103420-77-5/Devazepide; 9002-72-6/Growth Hormone; 9011-97-6/Cholecystokinin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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