Effect of leucine and valine supplementation on liver lipid accumulation and proinflammation in diet-induced obese mice

Abstract

Recent interest was forced on non-alcoholic fatty liver disease (NAFLD) related to the metabolic syndrome. The prevalence of NAFLD in Japan is increasing and estimated as about 30%. Branched chain amino acids (BCAA) has been reported to promote skeletal muscle synthesis, and suppressive effects of organ lipid accumulation has been also reported. The aim of this study is to estimate the effects of BCAA on the liver lipid accumulation and proinflammation in diet-induce obesity mice. Five-week old male C57BL/6J mice fed a high fat diet (50 energy % by lard) and test diet containing 20% casein (CO as control), 12% leucine and 5% valine mixture (LV) for 12 weeks. Liver triglyceride accumulation was significantly decreased in the LV group. Significant differences between CO and LV group were not observed in mRNA expression of TNF-alpha and a subunit of the NADPH oxidase enzyme, which is proinflammatory markers, and lipid metabolism-related enzymes were not observed. Acyl-CoA oxidase (ACOX) activity was significantly higher in the LV group compared with the CO group, whereas the activity of FAS was not significantly different. These results suggest that leucine and valine suppresses liver lipid accumulation through the activate in of the ACOX.