Reduced adipose tissue mass and hypoleptinemia in iNOS deficient mice: effect of LPS on plasma leptin and adiponectin concentrations

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Abstract
The aim of this study was to evaluate the impact of the lack of inducible NO synthase (iNOS) on body weight and adipose tissue mass as well as on plasma leptin and adiponectin in basal conditions and 6 h after lipopolysaccharide (LPS) administration in mice. Body weight was not different among male, six-week-old wild-type (WT) and iNOS−/− animals. However, the amount of epididymal white adipose tissue (EWAT) in iNOS−/− mice was significantly reduced (P<0.05). Circulating leptin and leptin mRNA in EWAT were decreased in iNOS−/− mice (P<0.05 and P<0.01, respectively). Plasma adiponectin and adiponectin mRNA were unchanged. LPS administration increased plasma leptin in both genotypes (P<0.05). Neither genotype nor treatment changed plasma adiponectin. In summary, iNOS−/− mice exhibited normal body weight but reduced adipose mass accompanied by hypoleptinemia. Leptin responsiveness to LPS in iNOS−/− mutants is preserved, showing that the LPS-induced rise in leptin is independent of the presence of functional iNOS. In addition, iNOS deficiency or LPS does not influence expression and circulating levels of adiponectin