Flaxseed lignan attenuates high-fat diet-induced fat accumulation and induces adiponectin expression in mice

Key Findings

Obesity is a major risk factor for various diseases and is associated with altered lipid metabolism, including fat oxidation and fatty acid synthesis. In the present study, the effects of the flaxseed lignan SDG were examined on high-fat diet-induced obesity in C57BL/6 mice. SDG improved high fat diet-induced visceral and liver fat accumulation, hypercholesterolaemia, hyperinsulinaemia and hyperleptinaemia. The adipocytokine adiponectin is believed to decrease TAG and to improve insulin resistance in obesity. Here flaxseed lignans induced the expression of adiponectin in white adipose tissue in diet induced obesity in mice. Flaxseed lignans are suggested to regulate adipogenesis-related gene expression through an increase in PPARg DNA binding activity. SDG beneficially affected high-fat diet-induced obesity in mice.

ABSTRACT

Flaxseed lignan secoisolariciresinol diglucoside (SDG) has been reported to prevent and alleviate lifestyle-related diseases including diabetes and hypercholesterolaemic atherosclerosis. This study assesses the effect of SDG on the development of diet-induced obesity in mice and the effect of the SDG metabolite enterodiol (END) on adipogenesis in 3T3-L1 adipocytes. We compared body weight, visceral fat weight, liver fat content, serum parameters, mRNA levels of lipid metabolism-related enzymes and adiponectin in mice fed either a low-fat diet (5% TAG), high-fat diet (30% TAG) or high-fat diet containing 0•5 and 1•0% (w/w) SDG for 4 weeks. Administration of SDG to mice significantly reduced high fat diet-induced visceral and liver fat accumulation, hyperlipaemia, hypercholesterolaemia, hyperinsulinaemia and hyperleptinaemia. SDG also suppressed sterol regulatory element binding protein 1c mRNA level in the liver and induced increases in the adiponectin mRNA level in the white adipose tissue and carnitine palmitoyltransferase I mRNA level in the skeletal muscle. Differentiated 3T3-L1 adipocytes were treated with 0, 5, 10 and 20mmol/l END and then assayed for mRNA expression of adipogenesis-related genes and DNA binding activity of PPARg to the PPAR response element consensus sequence. END induced adipogenesis-related gene mRNA expression including adiponectin, leptin, glucose transporter 4 and PPARg, and induced PPARg DNA binding activity in 3T3-L1 adipocytes. In conclusion, SDG induced adiponectin mRNA expression and showed beneficial effects on lipid metabolism in diet-induced obesity in mice. Flaxseed lignans are suggested to regulate adipogenesis- related gene expressions through an increase in PPARg DNA binding activity.