Anti-inflammatory effects of yerba mate extract (Ilex paraguariensis) ameliorate insulin resistance in mice with high fat diet-induced obesity

The aim of the present study was to evaluate the effects of yerba mate extract upon markers of insulin resistance and inflammatory markers in mice with high fat diet-induced obesity. The mice were introduced to either standard or high fat diets. After 12 weeks on a high fat diet, mice were randomly assigned to one of the two treatment conditions, water or yerba mate extract at 1.0 g kg(-1). After treatment, glucose blood level and hepatic and soleus muscle insulin response were evaluated. Serum levels of TNF-alpha and IL-6 were evaluated by ELISA, liver tissue was examined to determine the mRNA levels of TNF-alpha, IL-6 and iNOS, and the nuclear translocation of NF-kappa B was determined by an electrophoretic mobility shift assay. Our data show improvements in both the basal glucose blood levels and in the response to insulin administration in the treated animals. The molecular analysis of insulin signalling revealed a restoration of hepatic and muscle insulin substrate receptor (IRS)-1 and AKT phosphorylation. Our data show that the high fat diet caused an up-regulation of the TNF-alpha, IL-6, and iNOS genes. Although after intervention with yerba mate extract the expression levels of those genes returned to baseline through the NF-kappa B pathway, these results could also be secondary to the weight loss observed. In conclusion, our results indicate that yerba mate has a potential anti-inflammatory effect. Additionally, these data demonstrate that yerba mate inhibits hepatic and muscle TNF-alpha and restores hepatic insulin signalling in mice with high fat diet-induced obesity. (C) 2011 Elsevier Ireland Ltd. All rights reserved.