title: Regulation of feeding behavior and food intake by appetite-regulating peptides in wild-type and growth hormone-transgenic coho salmon.
abstract: Survival, competition, growth and reproductive success in fishes are highly dependent on food intake, food availability and feeding behavior and are all influenced by a complex set of metabolic and neuroendocrine mechanisms. Overexpression of growth hormone (GH) in transgenic fish can result in greatly enhanced growth rates, feed conversion, feeding motivation and food intake. The objectives of this study were to compare seasonal feeding behavior of non-transgenic wild-type (NT) and GH-transgenic (T) coho salmon (Oncorhynchus kisutch), and to examine the effects of intraperitoneal injections of the appetite-regulating peptides cholecystokinin (CCK-8), bombesin (BBS), glucagon-like peptide-1 (GLP-1), and alpha-melanocyte-stimulating hormone (α-MSH) on feeding behavior. T salmon fed consistently across all seasons, whereas NT dramatically reduced their food intake in winter, indicating the seasonal regulation of appetite can be altered by overexpression of GH in T fish. Intraperitoneal injections of CCK-8 and BBS caused a significant and rapid decrease in food intake for both genotypes. Treatment with either GLP-1 or α-MSH resulted in a significant suppression of food intake for NT but had no effect in T coho salmon. The differential response of T and NT fish to α-MSH is consistent with the melanocortin-4 receptor system being a significant pathway by which GH acts to stimulate appetite. Taken together, these results suggest that chronically increased levels of GH alter feeding regulatory pathways to different extents for individual peptides, and that altered feeding behavior in transgenic coho salmon may arise, in part, from changes in sensitivity to peripheral appetite-regulating signals.
authors.affiliation: Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada. Electronic address: whitesamantha.77@gmail.com.
authors.forename: Samantha L
authors.initials: SL
authors.lastname: White
authors.affiliation: Departments of Biology and Biochemistry, Memorial University of Newfoundland, St John's, NL A1B 3X9, Canada. Electronic address: hvolkoff@mun.ca.
authors.forename: Helene
authors.initials: H
authors.lastname: Volkoff
authors.affiliation: Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC V7V 1N6, Canada. Electronic address: Robert.Devlin@dfo-mpo.gc.ca.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Devlin
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001066:Appetite / Q000187:drug effects / Q000502:physiology*; D001839:Bombesin / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D005838:Genotype; D052216:Glucagon-Like Peptide 1 / Q000494:pharmacology; D013006:Growth Hormone / Q000235:genetics*; D017684:Oncorhynchus kisutch / Q000235:genetics*; D012621:Seasons; D000521:alpha-MSH / Q000494:pharmacology
chemical_list: D000521:alpha-MSH; D052216:Glucagon-Like Peptide 1; D013006:Growth Hormone; D002766:Cholecystokinin; D001839:Bombesin
keywords: Anorexigenic peptide; Coho salmon; Food intake; Growth hormone; Intraperitoneal injection; Oncorhynchus kisutch; Orexigenic peptide; Transgenic