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Original

Chronic insulin treatment causes insulin resistance in 3T3-L1 adipocytes through oxidative stress

, , , &
Pages 582-591 | Received 24 Mar 2008, Published online: 07 Jul 2009
 

Abstract

Insulin resistance and hyperinsulinemia are commonly present in obesity and pre-diabetes, and hyperinsulinemia is both a marker and a cause for insulin resistance. However, the molecular link between hyperinsulinemia and insulin resistance remains elusive. The present study examined the effect of chronic insulin treatment on the reactive oxygen species (ROS) production, insulin signalling and insulin-stimulated glucose uptake in 3T3-L1 adipocytes. The results showed that chronic insulin treatment significantly increased the intracellular generation of superoxide anion, hydrogen peroxide and hydroxyl radical. ROS induced by chronic insulin treatment inhibited insulin signalling and glucose uptake, induced endoplasmic reticulum (ER) stress and JNK activation. Furthermore, these effects were reversed by antioxidants N-acetylcysteine, superoxide dismutase or catalase. These results suggested that ROS, ER stress and JNK pathway are involved in insulin resistance induced by chronic insulin treatment. Therefore, oxidative stress could be a potential interventional target for hyperinsulinemia-induced insulin resistance and related diseases.

Abbreviations
CM-DCF-DA=

5-(and-6)-chloromethyl-2′,7′-dichlorofluorescen diacetate

DMPO=

5,5-dimethyl-1-pyrroline N-oxide

DPI=

diphenyleneiodonium

ER=

endoplasmic reticulum

ESR=

electron spin resonance

FACS=

fluorescence-activated cytometry sorter

FBS=

foetal bovine serum

IR=

insulin receptor

JNK=

c-Jun N-terminal kinase

NAC=

N-acetyl-L-cysteine

PBS=

phosphate-buffered saline

ROS=

reactive oxygen species

SOD=

superoxide dismutase

Abbreviations
CM-DCF-DA=

5-(and-6)-chloromethyl-2′,7′-dichlorofluorescen diacetate

DMPO=

5,5-dimethyl-1-pyrroline N-oxide

DPI=

diphenyleneiodonium

ER=

endoplasmic reticulum

ESR=

electron spin resonance

FACS=

fluorescence-activated cytometry sorter

FBS=

foetal bovine serum

IR=

insulin receptor

JNK=

c-Jun N-terminal kinase

NAC=

N-acetyl-L-cysteine

PBS=

phosphate-buffered saline

ROS=

reactive oxygen species

SOD=

superoxide dismutase

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