Lycopene alleviates high carbohydrate diet induced hepatic steatosis in black seabream (Acanthopagrus schlegelii): Potential for nutritional intervention

Lycopene (Lyc), a plant-derived carotenoid known for regulating glucose and lipid metabolism, which are used to investigate the effects of dietary Lyc supplementation on juvenile black seabream (Acanthopagrus schlegelii) (initial weight, 2.20 ± 0.02 g). A ten-week feeding trial was performed by employing four experimental diets: a regular carbohydrate diet (Control, 22.81 % nitrogen-free extract, NFE); a high-carbohydrate diet (HCD, 32.71 % NFE), and two HCD diets supplemented with 24.50 mg/kg (HCD + L1) or 48.80 mg/kg (HCD + L2) of Lyc. Results showed that dietary Lyc supplementation improved glucose tolerance and insulin resistance, while significantly reducing liver glycogen content and lipid droplet accumulation. In contrast, muscle glycogen content was upregulated compared to the HCD group. At the molecular level, Lyc supplementation activated the ins/pi3k/akt pathway, contributing to a dramatic up-regulation in the transcription of glucose transporters (glut2), along with key glycolytic genes (gk and pfk). Conversely, the transcription of gluconeogenesis-related genes (pepck and g6pc) was downregulated. Moreover, Lyc supplementation activated the ampkα/sitrt1 pathway, generating a considerable lessening in the transcription of lipid biosynthesis genes (srebp-1c, fas, accα, and g6pd). Alternatively, the transcription of lipolysis-related genes (pparα, acox3, and atgl) were upregulated, promoting hepatic lipid depletion. Correspondingly, TG and LDL-c levels, as well as ALT and AST activities, were reduced. In conclusion, dietary Lyc supplementation alleviated liver glycogen accumulation and lipid deposition induced by HCD. These findings suggest that Lyc effectively improves glucose and lipid metabolism, offering therapeutic potential for metabolic disorders in A. schlegelii.