Metformin attenuates high-carbohydrate diet-induced redox imbalance, inflamation and mitochondrial dysfunction in Megalobrama amblycephala

Abstract This study aimed to investigate the effects of dietary metformin supplementation on the redox balance, inflammation and mitochondrial biogenesis and function in blunt snout bream fed a high-carbohydrate (HC) diet. Fish (45.12 ± 0.36 g) were randomly offered four diets, including a control diet (33% carbohydrate), a HC diet (45% carbohydrate) and the HC diet supplemented with 0.06% (HCM1) and 0.12% (HCM2) metformin respectively for 12 weeks. Compared with the control, feeding the HC diet significantly increased the hepatosomatic index (HSI), the mesenteric fat index, liver and muscle glycogen contents, liver and adipose tissue lipid contents, plasma glucose and glycation end products (AGES) levels and aspartate transaminase activity, plasma and liver malondialdehyde (MDA) contents, hepatic adenosine triphosphate (ATP) and adenosine monophosphate (AMP) contents, mitochondrial cytochrome c content, mitochondrial complex IV activity and ATP 6 transcription, but decreased plasma catalase (CAT) activity, muscle superoxide dismutase (SOD) activity, hepatic antioxidant enzymes activities and the transcriptions of transforming growth factor β (TGFβ) and interleukin 10 (IL10). Compared with the HC group, metformin treatment (especially the HCM2 group) significantly elevated tissue glycogen contents, muscle SOD activity, plasma and liver antioxidant enzymes activities, the transcriptions of TGFβ and IL10, the sodium/potassium ATPase activity, the contents of mitochondrial protein and AMP, the level of p-AMP activated protein kinase (AMPK) and the p-AMPK/t-AMPK ratio, but lowered the HSI, tissue lipid contents, plasma levels of glucose, AGES and glycated serum protein, plasma and liver MDA contents, the transcriptions of IL1β, NADH dehydrogenase subunit 1 and ATP 6, the contents of ATP and cytochrome c, the ATP/AMP ratio and the activities of complexes I and IV. In conclusion, metformin could attenuate the HCdiet-induced redox imbalance, inflammation and mitochondrial dysfunction in blunt snout bream.