Flaxseed Lignans Promoted the Growth of Skeletal Muscle in Male Rats and Its Possible Mechanism

This study was aimed to determine whether flaxseed lignans could affect the growth of skeletal muscle in male animals and its possible mechanisms. The impact of flaxseed lignans on the skeletal muscle in male rats was determined in vivo. Flaxseed lignans (50 ppm) and daidzein (5 ppm) were added into the basal diets, respectively. The concentrations of serum lignans and daidzein were measured by high performance liquid chromatography (HPLC), and the serum growth hormone and testosterone (T) levels were analyzed by radioimmunoassay (RIA), and the expression of estrogen receptor β (ER β) in the soleus muscle and hypothalamus were determined by reverse-transcription polymerase chain reaction (RT-PCR). Flaxseed lignans and daidzein could significantly improve the feed efficiency and facilitate the weight gain of the femoral muscle in male rats. The ratio of RNA to DNA in the muscles and serum T levels was remarkably increased, whereas, the urea nitrogen concentrations were significantly decreased by flaxseed lignan and/or its metabolites and daidzein. Meanwhile, the expression of ER β in soleus muscle and hypothalamus were both upgraded by the two phytoestrogens. Flaxseed lignan promoted the growth of male rats, and it might be by regulating serum T levels by binding to ER β in the hypothalamus. In turn, it depressed the catabolism of protein and promoted the hypertrophy of skeletal muscle cells.