Nicotinamide riboside enhances liver regeneration via the MCART1/ASB3 axis in obesity-compromised rats

BACKGROUND: Obesity impairs liver regeneration by promoting chronic inflammation and metabolic dysfunction, especially in conditions like non-alcoholic fatty liver disease. Portal vein embolization (PVE), used to stimulate liver growth pre-hepatectomy, is less effective in obese subjects. Nicotinamide riboside (NR), a NAD+ precursor, improves mitochondrial function and lipid metabolism, but its role in liver regeneration under obese conditions remains unclear. Our study tried to investigate the effects and underlying mechanisms of NR on liver regeneration after PVE in high-fat diet (HFD)-induced obese rats. METHODS: HFD-fed rats underwent PVE and were treated with or without NR. Liver regeneration was assessed by histology, 5-ethynyl-2'-deoxyuridine (EdU) incorporation, immunohistochemistry, and liver function tests. NAD+ levels were quantified to confirm NR activity. Proteomics, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, Gene Ontology (GO) analysis, quantitative real-time PCR (qPCR), and western blotting were used to explore molecular mechanisms, focusing on the MCART1/ASB3 axis. RESULTS: Obesity impaired liver regeneration post-PVE, as evidenced by lipid accumulation, inflammation, reduced hepatocyte proliferation, and elevated liver enzymes. NR supplementation restored NAD+ levels, improved liver function, increased proliferative activity, and reduced steatosis. Mechanistically, NR upregulated MCART1 and ASB3 expression, promoting energy and lipid metabolism essential for regeneration. CONCLUSIONS: NR promotes liver regeneration after PVE in obese rats by enhancing NAD+-dependent metabolic pathways through the MCART1/ASB3 axis, offering a potential therapeutic strategy for obesity-associated liver dysfunction.