Dataset Information

A major role of insulin in promoting obesity-associated adipose tissue inflammation.

ABSTRACT:

Objective

Adipose tissue (AT) inflammation is associated with systemic insulin resistance and hyperinsulinemia in obese rodents and humans. A longstanding concept is that hyperinsulinemia may promote systemic insulin resistance through downregulation of its receptor on target tissues. Here we tested the novel hypothesis that insulin also impairs systemic insulin sensitivity by specifically enhancing adipose inflammation.

Methods

Circulating insulin levels were reduced by about 50% in diet-induced and genetically obese mice by treatments with diazoxide or streptozotocin, respectively. We then examined AT crown-like structures, macrophage markers and pro-inflammatory cytokine expression in AT. AT lipogenesis and systemic insulin sensitivity was also monitored. Conversely, insulin was infused into lean mice to determine its affects on the above parameters.

Results

Lowering circulating insulin levels in obese mice by streptozotocin treatment decreased macrophage content in AT, enhancing insulin stimulated Akt phosphorylation and de novo lipogenesis (DNL). Moreover, responsiveness of blood glucose levels to injected insulin was improved by streptozotocin and diazoxide treatments of obese mice without changes in body weight. Remarkably, even in lean mice, infusion of insulin under constant euglycemic conditions stimulated expression of cytokines in AT. Consistent with these findings, insulin treatment of 3T3-L1 adipocytes caused a 10-fold increase in CCL2 mRNA levels within 6 h, which was blocked by the ERK inhibitor PD98059.

Conclusion

Taken together, these results indicate that obesity-associated hyperinsulinemia unexpectedly drives AT inflammation in obese mice, which in turn contributes to factors that suppress insulin-stimulated adipocyte DNL and systemic insulin sensitivity.

SUBMITTER: Pedersen DJ

PROVIDER: S-EPMC4481426 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Publications

A major role of insulin in promoting obesity-associated adipose tissue inflammation.

Pedersen David J DJ Guilherme Adilson A Danai Laura V LV Heyda Lauren L Matevossian Anouch A Cohen Jessica J Nicoloro Sarah M SM Straubhaar Juerg J Noh Hye Lim HL Jung DaeYoung D Kim Jason K JK Kim Jason K JK Czech Michael P MP

Molecular metabolism 20150501 7

<h4>Objective</h4>Adipose tissue (AT) inflammation is associated with systemic insulin resistance and hyperinsulinemia in obese rodents and humans. A longstanding concept is that hyperinsulinemia may promote systemic insulin resistance through downregulation of its receptor on target tissues. Here we tested the novel hypothesis that insulin also impairs systemic insulin sensitivity by specifically enhancing adipose inflammation.<h4>Methods</h4>Circulating insulin levels were reduced by about 50% ...[more]

PMID: 26137438

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Dataset Information

A major role of insulin in promoting obesity-associated adipose tissue inflammation.

Objective

Methods

Results

Conclusion

Publications

A major role of insulin in promoting obesity-associated adipose tissue inflammation.

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