Impact of high fructose diet on visceral adiposity functionality

ALZAMENDI A; GIOVAMBATTISTA A; RASCHIA A; MARRA C; REBOLLEDO OR; GAILLARD RC; SPINEDI E

San Francisco, USA

Congreso; 90th Endocrine Society Meeting; 2008

The Endocrine Society

The aim of the present work was to evaluate changes in lipid metabolism and endocrine function of the visceral adipose tissue (VAT) in male rats with metabolic syndrome (MS) induced by a high fructose diet (HFD) (10% in the drink water [F10]) during three weeks. For this purpose, normal Wistar (F0) and F10 rats were sacrificed in basal condition and trunk blood was collected. Immediately after, VAT pads were dissected to determine in vitro the composition and release (by HPLC) of non-esterified fatty acids (NEFA) and to isolate adipocytes. These cells were 30 min incubated, without and with insulin (0.1-10 nM), for further evaluation of leptin secreted into the medium. Our data indicate that F10 rats displayed significant (p<0.05 vs. F0 values) changes in the circulating levels of NEFA (0.410.03 vs. 0.300.03 mM), triglycerides (0,990.07 vs. 0,74+0.06 g/l) and several adipokines [leptin (6.290.64 vs. 3.370.52 ng/ml), adiponectin (29.412,21 vs. 13.650.33 mg/ml) and PAI-1 (2.890.54 vs. 1.560.15 ng/ml)], with no changes in TNFa, CRP, total cholesterol, glucose and insulin peripheral concentrations. After in vitro incubation of VAT pads from both groups, a significant increase in NEFA secretion was observed in the F10 group (0.8210.083 vs. 0.5030.065 mg NEFA/g VAT; p < 0.02), and in the proportion of saturated NEFA (71.01.1 vs. 50.91.0 %; p < 0.001). These changes were accompanied by a significant decrease in unsaturated NEFA (30.71.1 vs. 56,12,0 %; p < 0.001). VAT leptin mRNA expression was 70 % higher in F10 rats (p < 0.05 vs. F0) and, conversely, VAT IRS-1 and IRS-2 mRNAs were 8 and 21 % diminished, respectively (p < 0.05 vs. F0). Finally, adipocytes from VAT of F10 rats spontaneously released a higher concentration of leptin (0.36+0.02 vs. 0.22+0.01 ng/ml; p < 0.05), and displayed an impaired (p < 0.05 vs. F0) response in leptin output after 30 min stimulation with graded concentrations of insulin. Our study indicates that HFD administration for three weeks induces a precocious development of changes in lipids and several adipokines circulating levels, and moification in VAT function (such as NEFA composition and release, leptin secretion, and diminished adipocyte sensitivity to insulin stimulation due to, at least in part, a reduction in its intracellular mediators). We conclude that changes in VAT functionality could be contributing to induce the overall endocrine-metabolic dysfunction characterizing the MS.