Abstract
Simple SummaryDietary chromium has been shown to reduce fat deposition and improve insulin action whereas dietary fat can increase fat deposition and cause insulin resistance. This study found that dietary nanoparticles of chromium picolinate, an organic form of chromium, caused changes in the genes involved in insulin action in both muscle and fat tissue that indicated improved insulin action. Conversely, a moderate increase in dietary fat caused changes consistent with increased fat deposition and reduced insulin action. In conclusion, nanoparticles of chromium picolinate offer a means of supplementing pigs diets to improve growth performance and carcass composition.The aim of this study was to investigate the interactive effects of dietary nano chromium picolinate (nCrPic) and dietary fat on genes involved in insulin signaling in skeletal muscle and subcutaneous adipose tissue of pigs. Forty-eight gilts were stratified on body weight into four blocks of four pens of three pigs and then within each block each pen was randomly allocated to four treatment groups in a 2 × 2 factorial design. The respective factors were dietary fat (22 or 57 g/kg) and dietary nCrPic (0 or 400 ppb nCrPic) fed for six weeks. Skeletal muscle samples were collected from the Longissimus thoracis and subcutaneous adipose tissue collected from above this muscle. Dietary nCrPic increased adiponectin, uncoupling protein 3 (UCP3) and serine/threonine protein kinase (AKT) mRNA expression, whereas dietary fat decreased adiponectin and increased leptin, tumor necrosis factor-α (TNF-α), peroxisome proliferator-activated receptors γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα) mRNA expression in adipose tissue. In skeletal muscle, dietary nCrPic increased phosphatidylinositol 3 kinase (PI3K), AKT, UCP3 and interleukin-15 (IL-15), as well as decreased suppressor of cytokine signaling 3 (SOCS3) mRNA expression. The improvement in insulin signaling and muscle mass and the reduction in carcass fatness by dietary nCrPic may be via decreased SOCS3 and increased UCP3 and IL-15 in skeletal muscle and increased adiponectin in subcutaneous adipose tissue.
Highlights
IntroductionObesity is associated with a number of health problems including the development of insulin resistance
The rapid rise in obesity is a critically important health issue worldwide
The present study evaluated the effect of dietary nano chromium picolinate and fat on adipogenesis and insulin signaling using the pig as a biomedical model
Summary
Obesity is associated with a number of health problems including the development of insulin resistance. Obesity is characterized by increased storage of fatty acids in an expanded adipose tissue mass and is closely associated with the development of insulin resistance in peripheral tissues such as skeletal muscle and adipose tissue [1]. High dietary fat intake has been implicated as a major cause of insulin resistance with several studies demonstrating an association between high-fat feeding and insulin resistance, suggesting a causal role of dietary fat in the pathophysiology of type 2 diabetes [2,3,4]. The molecular mechanisms leading to insulin resistance remain elusive, emerging evidence suggests that a high fat mass or the rate of fat deposition is strongly correlated with insulin resistance [5,6,7]. The transcriptional factors peroxisome proliferator-activated receptors (PPARs), C/EPB and sterol regulatory element-binding proteins (SREBPs) play important roles in adipogenesis [8]
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