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Obese mice lacking inducible nitric oxide synthase are sensitized to the metabolic actions of peroxisome proliferator-activated receptor-gamma agonism.

ABSTRACT: Synthetic ligands for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) improve insulin sensitivity in obesity, but it is still unclear whether inflammatory signals modulate their metabolic actions. In this study, we tested whether targeted disruption of inducible nitric oxide (NO) synthase (iNOS), a key inflammatory mediator in obesity, modulates the metabolic effects of rosiglitazone in obese mice.iNOS(-/-) and iNOS(+/+) were subjected to a high-fat diet or standard diet for 18 weeks and were then treated with rosiglitazone for 2 weeks. Whole-body insulin sensitivity and glucose tolerance were determined and metabolic tissues harvested to assess activation of insulin and AMP-activated protein kinase (AMPK) signaling pathways and the levels of inflammatory mediators.Rosiglitazone was found to similarly improve whole-body insulin sensitivity and insulin signaling to Akt/PKB in skeletal muscle of obese iNOS(-/-) and obese iNOS(+/+) mice. However, rosiglitazone further improved glucose tolerance and liver insulin signaling only in obese mice lacking iNOS. This genotype-specific effect of rosiglitazone on glucose tolerance was linked to a markedly increased ability of the drug to raise plasma adiponectin levels. Accordingly, rosiglitazone increased AMPK activation in muscle and liver only in obese iNOS(-/-) mice. PPAR-gamma transcriptional activity was increased in adipose tissue of iNOS(-/-) mice. Conversely, treatment of 3T3-L1 adipocytes with a NO donor blunted PPAR-gamma activity.Our results identify the iNOS/NO pathway as a critical modulator of PPAR-gamma activation and circulating adiponectin levels and show that invalidation of this key inflammatory mediator improves the efficacy of PPAR-gamma agonism in an animal model of obesity and insulin resistance.

SUBMITTER: Dallaire P

PROVIDER: S-EPMC2494686 | biostudies-literature | 2008 Aug

REPOSITORIES: biostudies-literature

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Obese mice lacking inducible nitric oxide synthase are sensitized to the metabolic actions of peroxisome proliferator-activated receptor-gamma agonism.

Dallaire Patrice P Bellmann Kerstin K Laplante Mathieu M Gélinas Stéphanie S Centeno-Baez Carolina C Penfornis Patrice P Peyot Marie-Line ML Latour Martin G MG Lamontagne Julien J Trujillo Maria E ME Scherer Philipp E PE Prentki Marc M Deshaies Yves Y Marette André A

Diabetes 20080505 8

<h4>Objective</h4>Synthetic ligands for peroxisome proliferator-activated receptor-gamma (PPAR-gamma) improve insulin sensitivity in obesity, but it is still unclear whether inflammatory signals modulate their metabolic actions. In this study, we tested whether targeted disruption of inducible nitric oxide (NO) synthase (iNOS), a key inflammatory mediator in obesity, modulates the metabolic effects of rosiglitazone in obese mice.<h4>Research design and methods</h4>iNOS(-/-) and iNOS(+/+) were su ...[more]

PMID: 18458147

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Project description:Data conflict with regard to whether peroxisome proliferator-activated receptor-? agonism suppresses inflammation in humans. We hypothesized that in healthy adults peroxisome proliferator-activated receptor-? agonism with fenofibrate would blunt the induced immune responses to endotoxin (lipopolysaccharide [LPS]), an in vivo model for the study of cardiometabolic inflammation.In the Fenofibrate and omega-3 Fatty Acid Modulation of Endotoxemia (FFAME) trial, 36 healthy volunteers (mean age 26±7 years, mean body mass index 24±3 kg/m(2), 44% female, 72% white) were randomized to fenofibrate 145 mg or placebo daily. After 6 to 8 weeks of treatment, subjects underwent a low-dose LPS challenge. Clinical and blood measurements were collected at randomization, before LPS administration, and serially for 24 hours after LPS administration. We examined area under the curve for evoked responses by treatment group. Compared to placebo, but before LPS challenge, fenofibrate reduced total cholesterol and tended to decrease triglycerides, consistent with achieved therapeutic plasma levels of fenofibric acid. In the placebo group, LPS induced a modest inflammatory response with increased cytokines and chemokines (2- to 4-hour post-LPS 8-fold increase in tumor necrosis factor-?, 9-fold increase in interleukin-6, 9-fold increase in interleukin-10, and 10-fold increase in monocyte chemotactic protein-1; all P<0.001) and acute-phase reactants (24-hour post-LPS 15-fold increase in serum amyloid A and 9-fold increase in C-reactive protein; both P<0.001). Compared to placebo, however, fenofibrate did not significantly attenuate LPS-induced levels of plasma cytokines, chemokines, or acute-phase proteins.These data suggest a lack of systemic antiinflammatory properties of fenofibrate at clinically relevant dosing in humans.URL: http://clinicaltrials.gov/ct2/show/NCT01048502. Unique identifier: NCT01048502. (J Am Heart Assoc. 2012;1:e002923 doi: 10.1161/JAHA.112.002923.).

Dataset Information

Obese mice lacking inducible nitric oxide synthase are sensitized to the metabolic actions of peroxisome proliferator-activated receptor-gamma agonism.

Publications

Obese mice lacking inducible nitric oxide synthase are sensitized to the metabolic actions of peroxisome proliferator-activated receptor-gamma agonism.

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