[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.
Zhang
Zhaofeng
Z
Department of Nutrition and Food Hygiene, School of Public Health, Peking University, Beijing 100191, China.
Zhao
Ming
M
Wang
Junbo
J
Ding
Ye
Y
Dai
Xiaoqian
X
Li
Yong
Y
D000108:Acetylcarnitine / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D004195:Disease Models, Animal; D055504:Insulin Receptor Substrate Proteins / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D032342:Muscle Cells / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D014409:Tumor Necrosis Factor-alpha; D000108:Acetylcarnitine