Comparative analysis of glucose metabolism responses of large yellow croaker Larimichthys crocea fed diet with fish oil and palm oil.

In order to study the effects of dietary fatty acid compositions on glucose metabolism, large yellow croaker juveniles Larimichthys crocea (initial weight, 36.80 ± 0.39 g) were fed with two experiment diets for 12 weeks. The two diets contained 6.5% of fish oil (FO) and palm oil (PO), respectively. Results showed that the contents of saturated fatty acids in liver and muscle, levels of glucose, triglyceride (TG), non-esterified fatty acid (NEFA), and leptin in blood were significantly higher in PO group, while the hepatic glycogen and muscle glycogen significantly decreased (P < 0.05). There were no significant differences in blood insulin and adiponectin levels between the two groups (P > 0.05). Compared with the FO group, the expressions of glucokinase (GK), glucose-6-phosphate dehydrogenase, glycogen synthase (GYS), glucose transporter 2 (GLUT2), insulin receptor 1 (IR1), insulin receptor substrate 1 (IRS1), insulin receptor substrate (IRS2), and protein kinase B (AKT2) were significantly decreased, and the expressions of phosphoenolpyruvate carboxykinase (PEPCK) in liver were significantly increased in the PO group. Meanwhile, the expressions of GK, phosphofructokinase, GYS, GLUT4, and insulin receptor 2 (IR2) were significantly reduced, and the expressions PEPCK, fructose-1 and 6-diphosphatase in muscle were significantly increased in the PO group. In conclusion, palm oil in diet could inhibit the utilization of glucose and promote the endogenous glucose production in large yellow croaker by reducing the sensitivity of insulin, so as to increase the blood glucose level.