[Effect of acetyl-L-carnitine on the insulin resistance of L6 cells induced by tumor necrosis factor-alpha].

OBJECTIVE

To investigate the effects of acetyl-L-carnitine (ALC) on the insulin resistance of rat L6 cells induced by tumor necrosis factor-alpha (TNF-alpha).

METHODS

Well-differentiated rat L6 muscle cells were divided into 6 groups, including control group, insulin (100 nmol/L) group, insulin (100 nmol/L) + TNF-alpha (10 ng/ml) group, and three insulin + TNF-alpha + ALC (0.1, 0.3 and 0.6 mmol/L respectively) groups. The glucose remained in culture medium was measured by the method of glucose oxidizes peroxides (GOD-POD). The glucose uptake of L6 cells was tested by [3H]-2-deoxyglucose. The expression of insulin receptor substrate-1 (IRS-1) was examined by western blotting.

RESULTS

The glucose content remained in culture medium was increased by TNF-alpha and the glucose uptake of cells was inhibited by TNF-alpha. The inhibition of TNF-alpha could be improved by ALC and in a dose-response relation. Compared with the insulin group, the expression of Ser307 phosphorylation of IRS-1 was lower in TNF-alpha group, and the expression of Ser307 phosphorylation of IRS-1 was decreased by ALC.

CONCLUSIONS

The insulin resistance in L6 cells induced by TNF-alpha might be attenuated by ALC via decreasing the expression of Ser307 phosphorylation of IRS-1.