Effects of dietary genistein on hepatic lipid metabolism and mitochondrial function in mice fed high-fat diets.

Objective: Genistein has been suggested to prevent insulin resistance and its related diseases. We investigated the effects of dietary genistein at different levels on hepatic lipid levels and mitochondrial functions in mice fed high-fat diets.

Methods: C57BL/6J mice were randomly divided into four groups and fed a high-fat diet containing genistein at levels of 0%, 0.1%, 0.2%, and 0.4% (HF, HF + 0.1G, HF + 0.2G, and HF + 0.4G) for 12 wk. We measured lipid levels in the blood and liver. We also observed messenger RNA (mRNA) expression of genes encoding proteins related to lipid and energy metabolism and antioxidant defense system and mitochondrial enzyme activities in the liver.

Results: The induction of fatty liver by HF was substantially decreased in the HF + 0.2G and HF + 0.4G groups. Peroxisome proliferator-activated receptorgamma coactivator mRNA was increased by HF + 0.4G. Although genistein did not affect peroxisomal acyl-CoA oxidase mRNA expression, it increased medium-chain acyl-CoA dehydrogenase mRNA expression in a dose-dependent manner and HF + 0.2G increased uncoupling protein-2 mRNA expression two-fold relative to HF mice. Genistein decreased malondialdehyde levels and increased glutathione levels in liver homogenates, regardless of dose. The HF + 0.1G diet increased mitochondrial glutathione peroxidase activity and mitochondrial succinate dehydrogenase activity.

Conclusions: Although genistein at higher levels decreased hepatic fat accumulation possibly by increasing fatty acid oxidation and uncoupling protein, low-dose genistein increased mitochondrial enzyme activities in mice with fatty liver and obesity induced by high-fat diets.