Glucocorticoid effects on glucose transport and transporter gene expression in L6 muscle cells

We questioned whether glucocorticoids alter the known potent effect of serum to increase glucose transport and GLUT-1 expression in cultured L6 myotubes. Myotubes were exposed to serum-free medium for 24h in the presence or absence of 300 nM dexamethasone and subsequently treated for 8h with 10% serum or serum free medium in the continued presence or absence of the glucocorticoid. Dexamethasone did not effect the serum-induced increase in GLUT-1 mRNA. However, dexamethasone increased GLUT-1 mRNA 2-3 fold versus the absence of dexamethasone after serum withdrawal. Dexamethasone also resulted in higher GLUT-1 protein levels and ameliorated the loss of glucose transport activity seen after serum withdrawal.