Objectives: This study aims to observe the preventive effect of nicotinamide riboside (NR) on fructose-induced lipid metabolism disorders and explore its mechanism. Methods: Male C57BL/6J mice were fed a 20% fructose solution and given 400 mg/kg NR daily by gavage for 10 weeks. Results: The results indicated that NR supplementation significantly reduced the body weight, liver weight, white adipose tissue (WAT) weight, serum, and hepatic lipid levels. NR upregulated the protein expression levels of sirtuin-1 (SIRT1), AMP-activated protein kinase (AMPK), PR domain containing 16 (PRDM16), uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor-gamma coactiva-tor-1-alpha (PGC-1α), nuclear respiratory factor 1-encoding gene (NRF1), mitochondrial transcription factor A (TFAM), cluster of differentiation 137 (CD137), transmembrane protein 26 (TMEM26), and T-box 1 (TBX1). Moreover, NR enhanced the Actinobacteria and Enterorhabdus abundance. Spearman’s correlation analysis revealed that significant correlations exist between Firmicutes, Bacteroidetes, and Erysipelotrichaceae with browning-related indicators. Conclusions: In conclusion, NR could alleviate lipid metabolic abnormalities induced by fructose through activating SIRT1/AMPK-mediated browning of WAT. The mechanism by which NR improves fructose-induced lipid metabolism disorders may also be associated with the modulation of intestinal flora.

Objectives: The purpose of this study is to observe the preventive effect of folic acid (FA) combined with melatonin (MLT) on high-fat diet (HFD)-induced hepatic steatosis and to explore its potential mechanism. Methods: Fifty male C57BL/6J mice were randomized into five groups: control group (CN), high-fat diet group (HD), FA supplementation group (HF), MLT supplementation group (HM), and FA combined with MLT supplementation group (HFM). The experiment lasted for 10 weeks. Results: FA combined with MLT effectively inhibited HFD-induced increases in liver index, hepatic TG levels, and serum TG levels. Histological examination revealed that FA combined with MLT significantly reduced the area of hepatic steatosis and the accumulation of lipid droplets (LD). Western blot analysis showed FA combined with MLT activated AMPK, inhibiting the expression of ERS-related proteins, thereby reducing the expression of LD lipolysis-associated proteins. Conclusions: FA combined with MLT might prevent HFD-induced hepatic steatosis by attenuating ERS and subsequently promoting LD lipolysis.

Objective: To explore the preventive effect and mechanism of melatonin on high-fructose-induced renal injury in mice. Methods: A total of forty male C57BL/6J mice aged six weeks were randomly assigned to four groups: control group (CON), melatonin group (MLT), fructose group (FRU), and fructose + melatonin group (FRU + MLT). The concentration of the fructose solution was 30%, and the dose of melatonin was 10 mg/kg/day by intragastric administration. The experiment lasts for 10 weeks. Results: Liquid intake and energy intake were comparable between the FRU and FRU + MLT, both of which were significantly higher than that in the CON and MLT. MLT inhibited fructose-induced increased levels in serum creatinine (Cre), serum urea nitrogen (BUN), serum uric acid (UA), serum triglyceride (TG), renal kidney injury molecule-1 (KIM-1), and renal TG. Hematoxylin and Eosin (H&E) staining and Oil Red O (ORO) staining showed that MLT alleviated renal tubular dilatation, loss of brush border, epithelial cell detachment and lipid accumulation. Transmission electron microscope (TEM) observations showed that MLT increased autophagic vacuoles among mitochondria. Western blot analysis showed that, compared with the FRU, the FRU + MLT had elevated expression of AMP-activated protein kinase (AMPK) phosphorylation, along with a significant increase in the expression of its downstream mitophagy-related proteins (including PINK1, Parkin, LC3 II, and Beclin1), whereas the expression of p62 was markedly decreased. Furthermore, the expression levels of FAO-related proteins (including PPARα and CPT1A) in the FRU + MLT were significantly upregulated. Conclusions: MLT alleviates renal injury caused by high-fructose exposure in male mice and its mechanism might be associated with the regulation of mitophagy and fatty acid oxidation.