The long-term effects of dietary carbohydrates on glucose metabolism in rainbow trout (Oncorhynchus mykiss)

Much remains unknown about the physiological effects of prolonged dietary carbohydrates on carnivorous fish such as rainbow trout, Oncorhynchus mykiss. In this thesis, the long-term effects of carbohydrates on trout glucose regulation are investigated by characterizing the metabolite profiles of fish fed with or without carbohydrates. Two groups of fish were maintained on either carbohydrate-rich (HC, 32.9% of diet by weight) or deficient (LC, 1% of diet by weight) diets for a six-month period. Plasma, liver and muscle tissue samples were assayed for various metabolites. Intravenous glucose tolerance tests were performed in each group and showed no significant differences in glucose tolerance. Continuous tracer infusion was used to measure glucose turnover in each group to determine whether changes in glucose concentration in response to a glucose load were due to changes in rates of glucose appearance (Ra), disappearance (Rd) or both. This research has demonstrated that rainbow trout can acclimate to high carbohydrate diets and modify several physiological parameters and biochemical pathways to both utilize and store newly available energy provided in the form of dietary glucose. (Abstract shortened by UMI.