The coordination of organismal growth involves the integration of many external and internal cues that result in the production of numerous hormones and growth factors, including growth hormone (GH) and insulin-like growth factor-I (IGF-I). An understanding of how the various cues are integrated and how the interplay of hormones modulate growth is far from complete. In this project, rainbow trout will be used as a model organism to evaluate the effects of somatostatins (SSs), a multi-functional family of peptide hormones, on the growth control network. Research will reveal the influence of SSs on GH responsiveness in selected cell types (e.g., liver). This will involve the characterization of GH receptors (GHR) and an analysis of the effects of SSs on GHR expression. Research also will elucidate the influence of SSs on IGF-I synthesis and secretion. In addition, the effects of SS on IGF-I responsiveness in selected cell types (e.g., muscle) will be determined. This will involve an analysis of IGF-I binding characteristics and of IGF-I receptor expression. Lastly, the mechanisms of SS action will be characterized by identifying signal pathways through which SSs operate and by establishing which SS receptor subtype activates which signal pathway. The results of this project will advance our understanding of normal growth control processes and have application to efforts to improve growth efficiency of fish (e.g., aquaculture), poultry and domestic livestock, as well as to the detection and treatment of growth disorders in animals and humans. In addition, the project will expand critical research infrastructure in North Dakota, serving to diversify the nation's scientific enterprise, and afford research education and training opportunities to undergraduate and graduate students, including members of underrepresented groups.
