Insights into the correlations between prebiotics and carbohydrate metabolism in fish: Administration of xylooligosaccharides in Megalobrama amblycephala offered a carbohydrate-enriched diet

Abstract

Dietary supplementation of xylooligosaccharides (XOS) represents a potential means to improve the carbohydrate metabolic disorders in type 2 diabetes. However, whether XOS could improve the carbohydrates utilization and metabolism of fish is still unknown. This study investigated the effects of XOS on the growth performances and glycolipid metabolism of blunt snout bream (Megalobrama amblycephala) fed a high carbohydrate (HC) diet. Fish (44.69 ± 0.11 g) were fed a control diet (29% carbohydrate), a HC diet (41% carbohydrate), and the HC diet supplemented with 0.5%, 1.0%, 1.5% and 2.0% XOS respectively for 12 weeks. Compared with the control group, the HC group obtained significantly high values of final body weight, weight gain rate, intraperitoneal fat ratio, whole-body lipid content, liver and intraperitoneal fat glycogen contents, tissue lipid contents, glycated serum protein (GSP) levels, and the transcriptions of sodium glucose cotransporter 1, glucose transporter 2 (glut2), glucokinase (gk), pyruvate kinase (pk), glycogen synthase (gs), fatty acid synthetase (fas) and acetyl-CoA carboxylase α (accα), and the decreased values of feed conversion ratio and hepatic transcriptions of carnitine palmitoyl transferase 1 (cpt-1) and acyl-CoA oxidase (aco). Meanwhile, the supplementation of 1.0% XOS significantly increased the nitrogen retention efficiency, liver glycogen contents, and the transcriptions of glut2, gk, pk, glucose-6-phosphate, cpt-1 and aco compared with the HC group, while the opposite was true for liver and muscle lipid contents, plasma TG, total cholesterol and GSP levels, and the transcriptions of fas and accα. Collectively, dietary supplementation of 1.0% XOS could improve the growth performance and glycolipid metabolism of blunt snout bream fed a high-carbohydrate diet by up-regulating glucose transport, glycolysis, glycogenesis, the pentose phosphate pathway and fatty acids β-oxidation, but down-regulating gluconeogenesis and fatty acid biosynthesis