1,25-Dihydroxyvitamin D improved the free fatty-acid-induced insulin resistance in cultured C2C12 cells

Diabetes Metab Res Rev. 2008 Sep;24(6):459-64. doi: 10.1002/dmrr.873.


Background: Epidemiological evidence has indicated that vitamin D deficiency increased the risk of insulin resistance in metabolic syndrome. The present study was conducted to test the hypothesis that 1,25-dihydroxyvitamin D may improve the free fatty-acid (FFA)-induced insulin resistance in muscle cells.

Method: The insulin resistance of muscle cell model was established by treatment of FFA in differentiated C2C12 cells. Glucose uptake of C2C12 myotubes was analysed by the 3H-labelled 2-deoxyglucose uptake assay. The diameter of myotubes was measured under the condition of glutaraldehyde-induced autofluorescense. Tyrosine phosphorylated insulin receptor substrate 1 (IRS-1) was measured by immunoprecipitation. Serine phosphorylated IRS-1 and protein kinase B (Akt), extracellular signal-related kinase (ERK), c-Jun amino-terminal kinases (JNK) as well as their phosphorylated form were analysed by Western blots.

Results: Compared with a vehicle-treated group, FFA treatment in myotubes was associated with 70.6% reduction in insulin-mediated uptake of glucose, a five-fold increase in serine phosphorylation of IRS-1, 76.9% decrease in tyrosine phosphorylation of IRS-1 and 81.8% decrease in phosphorylation of Akt. Supplement of 1,25-dihydroxyvitamin D improved the FFA-induced inhibition of glucose uptake in a dose- dependent (p < 0.001) and time-dependent manner (p < 0.01). This was accompanied by increase in tyrosine phosphorylation of IRS-1 and phosphorylated Akt and decrease in serine phosphorylation of IRS-1 (p < 0.001). 1,25-Dihydroxyvitamin D also inhibited the FFA-induced reduction in myotube diameter by 35.3% (p < 0.001). JNK phosphorylation was reduced by 126.7% with treatment of 1,25-dihydroxyvitamin D (p < 0.001). 1,25-Dihydroxyvitamin D had no effect on FFA-induced ERK phosphorylation (p = 0.84).

Conclusion: 1,25-Dihydroxyvitamin D improved the FFA-induced insulin resistance in muscle cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport / drug effects
  • Calcitriol / pharmacology*
  • Cell Line
  • Deoxyglucose / metabolism
  • Fatty Acids, Nonesterified / pharmacology*
  • Glucose / metabolism
  • Humans
  • Insulin Resistance / physiology*
  • Mice
  • Muscle Fibers, Skeletal / cytology
  • Muscle Fibers, Skeletal / drug effects
  • Muscle Fibers, Skeletal / physiology
  • Myoblasts / cytology
  • Myoblasts / drug effects
  • Myoblasts / physiology*


  • Fatty Acids, Nonesterified
  • Deoxyglucose
  • Calcitriol
  • Glucose