Branched-Chain Amino Acid–Rich Supplements Containing Microelements Have Antioxidant Effects on Nonalcoholic Steatohepatitis in Mice

Background: The aim of the present study was to elucidate whether the administration of antioxidant-rich nutrients, including branched-chain amino acids (BCAAs), microelements, and vitamins, both alone and in combination, has a positive impact on liver function in a nonalcoholic steatohepatitis (NASH) mouse model and identify the mechanisms underlying these effects. Methods: Seven-week-old male KKAy mice fed a methionine- and choline-deficient diet (MCD) for 4 weeks were divided into 7 groups and fed the following planned diets for another 4 weeks: group A (normal diet), group B (MCD; control), group C (MCD with rich microelements), group D (MCD with rich BCAAs), group E (MCD with rich microelements and BCAAs), and group F (MCD with rich microelements, BCAAs, and vitamins). We then conducted biochemical assays, histological analyses, immunohistochemistry for 8-hydroxy-2′-deoxyguanosine (8-OHdG) and 4-hydroxy-2′-nonenal (4-HNE), and Western blotting for insulin glucose signaling, lipid metabolism, and endoplasmic reticulum (ER) stress–related signaling in liver specimens obtained from mice in each group. Results: The morphometric grades of all NASH-related findings and the mean degree of 8-OHdG immunolocalization in groups D–F were significantly lower than those observed in group B. The expression levels of insulin receptor β subunit (IRβ) and p-elF in groups E and F and those of phosphatidyl-inositol 3 kinase (PI3K85), p-AcelCoA, and PERK in group F were similar to those noted in group A. Conclusions: The administration of a combination of antioxidant-rich nutrients, including BCAAs and microelements, is likely to suppress the progression of NASH by reducing oxidative stress, primarily via the downregulation of the ER stress pathway.