Early Programming Effects of a Hyperglucidic Diet on Carbohydrate and Lipid Metabolism in Gibel Carp (carassius Gibelio)

Previous nutritional studies have shown that intermediate metabolism in early fish development is highly plastic, and thus we hypothesized that there may be an early programming effect of a hyperglucidic diet on carbohydrate utilization in gibel carp. To test our hypothesis, gibel carp CAS Ⅴ (mean body weight: 0.10 g) were fed a high-carbohydrate/low protein (HC/LP) or low carbohydrate/high protein (LC/HP) diet for three weeks, and then were fed with normal feed for 12 weeks and a hyperglucidic diet for one week. We found that early HC/LP stimulus inhibited growth performance but altered the expression of glucose metabolism genes. After long-term feeding on the normal diet, the effects of early HC/LP stimulus were eliminated; these involved plasma metabolites, hepatic cholesterol, glycogen and triglyceride content, and glucose and lipid metabolism. However, the early HC stimulus group showed a better ability to maintain plasma glucose hemostasis when again given the HC diet. The capacity of carbohydrate and lipid metabolism in juvenile gibel carp was improved in the early HC diet group, as indicated by upregulated expression of genes related to glycolysis, lipid transport (gk, akt, srebp1, acc, fas, hsl, and acly) and downregulated expression of genes involved in gluconeogenesis (fbpase). Moreover, the early HC diet significantly upregulated AKT protein expression levels. The DNA methylation levels of akt in the HC/LP group were significantly lower than those in the LC/HP group. Overall, the study suggests that early HC stimulus in juvenile gibel carp can result in better carbohydrate utilization through DNA methylation of critical elements in the insulin signaling pathway.