Dietary naringenin modulates antioxidant status and hepatic lipid deposition in marine medaka (Oryzias dancena) fed a high-fat diet

High-fat diets (HFDs) are commonly used in aquaculture to enhance growth and reduce feed costs; however, prolonged feeding can induce oxidative stress, disrupt lipid metabolism, and impair physiological homeostasis. The present study evaluated the protective effects of naringenin (NGE) in the marine model fish Oryzias dancena fed a high-fat diet. Fish were fed one of four experimental diets for 45 days: a normal-fat diet (NFD, 8% crude lipid), a high-fat diet (HFD, 15% crude lipid), and HFD supplemented with 0.075% (HFD + N1) or 0.15% (HFD + N2) naringenin. Digestive enzyme activities, antioxidant status, lipid peroxidation, hepatic histology, and the expression of genes related to antioxidant defence, lipid metabolism, and immunity were assessed at the end of the feeding trial. HFD feeding selectively modulated digestive enzyme activities, characterized by increased lipase activity and reduced amylase activity. Muscle superoxide dismutase (SOD) activity was significantly reduced in HFD-fed fish, while catalase (CAT) activity showed no significant change but followed a similar directional trend. In contrast, hepatic expression of sod and gpx was upregulated, indicating tissue-specific oxidative stress responses. Alanine aminotransferase (ALT) activity was significantly reduced in the HFD group, whereas aspartate aminotransferase (AST) activity remained statistically unchanged, although a comparable pattern was observed. SOD activityon with naringenin, particularly at 0.15%, restored muscle SOD activity, enhanced total antioxidant capacity, reduced lipid peroxidation, and partially restored ALT activity. At the molecular level, HFD feeding upregulated pparδ and suppressed fads2 expression, indicative of lipid metabolic stress, which was modestly alleviated by naringenin supplementation. Histological analysis revealed pronounced hepatic lipid accumulation in HFD-fed fish, while naringenin supplementation significantly reduced hepatic vacuolation. Collectively, these findings demonstrate that dietary naringenin, particularly at 0.15%, mitigates HFD-induced oxidative stress and hepatic lipid accumulation in Oryzias dancena by enhancing antioxidant defence and modulating lipid metabolic pathways.