Growth in fish is regulated in part by the growth hormone (GH)-insulin-like growth factor (IGF) axis, and salmon transgenic for GH are known to show dramatic increased growth. However, little is known concerning the in vivo global levels of metabolites and the mechanism of enhancement of growth in GH transgenic vertebrates. The present study examined the charged metabolites levels in GH transgenic coho salmon (Oncorhynchus kisutch) overexpressing GH by metabolomic analysis. Triplicate groups of size-matched (0 year-old, approx. 60 g) and age-matched (1.5 years-old) GH transgenic (T) and non-transgenic (NT) wild salmon were quantitatively assessed for levels of approximately 200 metabolites in both muscle and liver. The most notable difference found between T and NT fish was that glycolysis metabolite levels were increased in the muscle of transgenic fish. In addition, an increase in some metabolite levels in the transgenic fish muscle was found to be enhanced by ration-restriction. However, these effects observed in muscle were different from that seen in liver. The results suggest that GH transgenesis can improve the use of carbohydrates as a source of energy associated with rapid growth. These effects are likely to depend on the level of total digestible energy intake and type of tissue in transgenic fish.
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