Location: Warmwater Aquaculture Research Unit
Title: Overview of the Gh-Igf Network in Regulating Growth in Channel Catfish Authors
Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: August 9, 2005
Publication Date: February 13, 2006
Citation: Peterson, B.C., Bilodeau, A.L., Small, B.C. 2006. Overview of the gh-igf network in regulating growth in channel catfish. Aquaculture America Conference. Las Vegas, NV 13-16, 2006, p. 231. Technical Abstract: The growth hormone-insulin like growth factor (GH-IGF) network plays an important role in the endocrine control of fish growth. However, the role of the GH-IGF system in mediating growth in channel catfish is poorly understood. Studies have been conducted in our laboratory to better understand the functions of GH, GH receptor (GHR), IGF-I, IGF-II, insulin like growth factor binding proteins (IGFBPs), and somatostatin (SS) in channel catfish. We have demonstrated that plasma GH concentrations increase in fasted catfish while abundance of hepatic GHR mRNA decreases. In addition, plasma levels of IGF-I decrease and a 20 kDa IGFBP increase in fasted catfish. We have also demonstrated that abundance of SS-14 mRNA in the hypothalamus and gut is increased due to fasting and is returned to control (fed) levels after fifteen days of refeeding. The presence of SS-22 mRNA has also been detected in the pancreas (Brockmann bodies) but its role is not clear at this time. The results of these studies suggest that the somatotropic axis in catfish is regulated in a similar manner to mammals. We have completed numerous studies addressing the roles of IGF-I and IGF-II in growth of channel catfish. Weight gain increased 48% in as little as six weeks in GH-injected catfish while hepatic IGF-I and IGF-II mRNA increased one day after injection. In comparison of fast and slow growing families of channel catfish, abundance of hepatic and muscle IGF-II mRNA were elevated in faster growing catfish compared to slower growing catfish. We have also shown a positive correlation (r2 = 0.72) between plasma levels of IGF-I and weight gain in three different strains of catfish. The results of these studies provide evidence that IGF-I and IGF-II play roles in growth of channel catfish. Evidence is growing that suggests that the GH-IGF system plays an important role in the growth of channel catfish. Future studies are aimed at determining how the GH-IGF network is coordinated with immune function, nutrition, and metabolism.