Chromium Improves Protein Deposition Through Regulating the mRNA Levels of IGF-1, IGF-1R,and Ub in Rat Skeletal Muscle Cells

The aim of this study was to evaluate the impact of three different chromium forms—chromic chloride (CrCl₃), chromium picolinate (CrPic), and a newly synthesized complex of chromium chelated with small peptides (CrSP)—on protein metabolism in vitro. In cultured skeletal muscle cells, CrSP was able to increase the basal and insulin-stimulated levels of protein deposition in skeletal muscles cells. CrCl₃ and CrPic augmented insulin-stimulated protein synthesis. At the molecular level, insulin significantly increased the mRNA levels of insulin-like growth factor 1 and insulin-like growth factor 1 receptor. These impacts could be enhanced by the addition of chromium, especially CrSP. The mRNA levels of ubiquitin were significantly reduced when cells were cultured with chromium or/and insulin. Assuming that the mRNA level increase or decrease results in increased or decreased levels of these proteins, chromium would improve protein anabolism and reduce protein catabolism and then prove protein deposition in rat skeletal muscle cells.