Document Detail


IGF-I stimulates reactive oxygen species (ROS) production and inhibits insulin-dependent glucose uptake via ROS in 3T3-L1 adipocytes.
MedLine Citation:
PMID:  20185348     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: IGF-I is known to enhance insulin sensitivity in whole body mainly via the IGF-I receptors in muscles. However, the effect of IGF-I on the regulation of insulin sensitivity in the adipose tissue is yet unclear. Insulin sensitivity was found to be higher in the IGF-I receptor-deficient adipocytes than that in wild-type adipocytes, suggesting that IGF-I signaling induces insulin resistance in adipocytes. However, the underlying mechanism has not yet been elucidated. In addition, the effect of superphysiological levels of IGF-I, as is observed in patients with acromegaly, on insulin sensitivity remains unclear. DESIGN: To clarify the role of IGF-I on insulin sensitivity in adipocytes, we determined insulin-induced glucose uptake and IRS-1 status in 3T3-L1 adipocytes treated with IGF-I. Since reactive oxygen species (ROS) are causally related to insulin resistance, we investigated the effect of IGF-I on ROS production to elucidate the molecular mechanism underlying insulin resistance. RESULTS: Preincubation of the adipocytes with IGF-I attenuated insulin-dependent glucose uptake. Interestingly, we found that IGF-I significantly stimulated ROS production. Furthermore, preincubation of adipocytes with an antioxidant, N-acetyl-cysteine (NAC) restored the IGF-I-induced attenuation of insulin-dependent glucose uptake; this indicates that IGF-I induces insulin resistance via ROS. Serine phosphorylation of IRS-1 was strongly induced and the insulin-dependent tyrosine phosphorylation of IRS-1 was suppressed by preincubating the adipocytes with IGF-I. Further, NAC restored these changes induced by IGF-I on both serine and tyrosine phosphorylation of IRS-1. CONCLUSIONS: These data indicate that IGF-I inhibited insulin activity in the 3T3-L1 adipocytes via ROS production, which affects IRS-1 phosphorylation status.
Authors:
Hidenori Fukuoka; Keiji Iida; Hitoshi Nishizawa; Mari Imanaka; Ryoko Takeno; Genzo Iguchi; Michiko Takahashi; Yasuhiko Okimura; Hidesuke Kaji; Kazuo Chihara; Yutaka Takahashi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-02-24
Journal Detail:
Title:  Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society     Volume:  20     ISSN:  1532-2238     ISO Abbreviation:  Growth Horm. IGF Res.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-05-24     Completed Date:  2010-09-17     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9814320     Medline TA:  Growth Horm IGF Res     Country:  Scotland    
Other Details:
Languages:  eng     Pagination:  212-9     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier Ltd. All rights reserved.
Affiliation:
Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
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MeSH Terms
Descriptor/Qualifier:
3T3-L1 Cells
Adipocytes / drug effects*,  metabolism
Animals
Glucose / pharmacokinetics*
Insulin / pharmacology*
Insulin Receptor Substrate Proteins / metabolism
Insulin Resistance / physiology
Insulin-Like Growth Factor I / pharmacology*
Mice
NADPH Oxidase / metabolism
Oxidative Stress / physiology
Phosphorylation / drug effects
Reactive Oxygen Species / metabolism*,  pharmacology
Chemical
Reg. No./Substance:
0/Insulin Receptor Substrate Proteins; 0/Irs1 protein, mouse; 0/Reactive Oxygen Species; 11061-68-0/Insulin; 50-99-7/Glucose; 67763-96-6/Insulin-Like Growth Factor I; EC 1.6.3.1/NADPH Oxidase

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