Poster Topical Area: Obesity
Location: Hall D
Poster Board Number: 637
White adipose tissue (WAT) is a metabolic and endocrine organ distributed in subcutaneous (SAT) and visceral (VAT) pads. In obesity, WAT is severely altered, accompanied by a reduction in circulating adiponectin and an increase in leptin. However, there is still controversy over which fat deposit contributes more for the production of these adipokines.
The pandemic of obesity has encouraged the identification of new risk factors involved in the pathogenesis of obesity, like environmental pollutants that can act as endocrine disruptors. Arsenic (As) is considered diabetogenic, but little is known if it interferes with WAT physiology if it is obesogen, and its modulation by nutritional components. Thus, environmental insults and their interactions must be studied to build up an integrative model of obesity.
Objectives: Determine the effects of As exposure in the presence of a high-fat diet (HFD) on serum leptin and adiponectin and its source of synthesis from different WAT depots.
Methods: Eight-week-old male C57BL/6 mice were fed control diet or HFD (39 kcal% fat) for 16 weeks. Half of each group was exposed to 100 µg/L iAsIII in drinking water for the last 8 weeks. Food intake and body weight were monitored weekly. Fasting serum leptin and adiponectin levels were measured at the end of the study. SAT, retroperitoneal and epididimal VAT (rVAT and eVAT) pads were recollected to evaluate the synthesis of these adipokines.
Results: Mice fed HFD with and without As, significantly increased SAT and rVAT weight, accompanied with significantly lower fasting serum adiponectin and higher leptin concentrations. Under control conditions, SAT expressed the lower leptin and adiponectin mRNA levels in comparison to VAT.
In SAT, As treatment alone or in combination with HFD reduced adiponectin mRNA abundance in the same magnitude. As treatment in combination with HFD, dramatically reduced adiponectin mRNA abundance in rVAT and eVAT.
As with HFD increased leptin mRNA abundance in eVAT but reduced it in rVAT, without changes in SAT.
Conclusions: VAT contributes more than SAT for leptin and adiponectin expression. The synthesis of these adipokines is affected by As exposure and is potentiated by HFD, particularly diminishing the gene expression of both adipokines in rVAT and increasing only the expression of leptin in eVAT.
Instituto de Investigaciones Biomédicas, UNAM
Mexico City, Distrito Federal, Mexico