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Keywords:

  • diabetes;
  • non-alcoholic fatty liver disease;
  • obesity;
  • OLETF ;
  • α-lipoic acid

Abstract

Background

Insulin resistance, oxidative stress, inflammation and innate immune system activation contribute to the development of non-alcoholic fatty liver disease (NAFLD) through steatosis and inflammation in the liver. The powerful antioxidant α-lipoic acid (ALA) has been shown to improve insulin sensitivity and suppress inflammatory responses. This study explores how ALA administration protects against NAFLD.

Methods

Otsuka Long-Evans Tokushima Fatty (OLETF) rats were divided into two groups (treated with 200 mg/kg/day of ALA or untreated) at 12 weeks of age and sacrificed at 28 weeks of age.

Results

Serum levels of insulin, free fatty acids, total cholesterol, triglyceride, leptin, IL-6 and blood glucose were decreased in ALA-treated rats. Serum adiponectin levels were higher in ALA-treated rats. ALA treatment decreased the expression of sterol regulatory element binding protein-1 and acetyl CoA carboxylase, and increased glucose transporter-4 expression in the livers of OLETF rats. Expression of the antioxidant enzymes heme oxygenase-1 and Cu/Zn-superoxide dismutase was increased in the livers of ALA-treated rats. The lipid peroxidation marker 4-hydroxynonenal was decreased in the liver of ALA-treated rats. Proteins associated with innate immune activation (Toll-like receptor-4 and high-mobility group protein box-1) and inflammatory markers (vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and cyclooxygenase-2) were decreased in the livers of ALA-treated rats.

Conclusions

Chronic ALA supplementation prevents NAFLD through multiple mechanisms by reducing steatosis, oxidative stress, immune activation and inflammation in the liver.