Fiber‐type skeletal muscle response to dietary selenium and isoflavone supplementation in male mice

Abstract

Previous research has shown selenium (Se) and isoflavone (IF) supplementation influences carbohydrate metabolism and insulin sensitivity. In response to different dietary IF contents and/or supplemental Se, we examined adaptations of mitochondrial proteins and FOXO1a in skeletal muscle. FOXO1a is a transcription factor that suppresses insulin sensitivity and alters glucose metabolism. Male FVB mice were fed diets for six months providing minimal IF or 500 mg/kg equivalents of genistein and daidzein. All other dietary components were equivalent. Selenium was administered by gavage daily (3mg/kg body wt/day as Se‐methylselenocysteine). Results show elevated dietary IF content decreased FOXO1a abundance in Tibialis Anterior (19±4.7%) and Red Quadriceps (RQ) (17±5%) vs. low IF. Supplemental Se decreased RQ FOXO1a levels in low IF mice (59±10% vs. control; p<0.001). Our data show Se also decreases FOXO1a in White Quadriceps (12±4%) and RQ (17±9%) vs. no Se overall. As Se had the greatest effect by decreasing FOXO1a in the RQ, we investigated changes in mitochondrial content by measuring Uncoupling Protein 3 (UCP3) and Cytochrome C (CytC) in the same muscle. Both increased in response to supplemental Se (CytC 126±43%, UCP3 99±31.5% elevated vs. control, p<0.05). These data suggest fiber‐type specific adaptation in response to supplemental Se and elevated dietary isoflavone content.