Jessica Weicht

German Institute of Human Nutrition, Berlín, Berlin, Germany

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Publications (4)11.29 Total impact

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    ABSTRACT: Obesity and insulin resistance are associated with low adiponectin levels, although adiponectin is exclusively expressed in white adipose tissue. The mechanism beyond that paradox is not entirely clear, although insulin itself may reduce circulating adiponectin levels. However, obesity is also associated with hyperlipidaemia and the effects of free fatty acids (FFAs) and triglycerides (TG) on circulating adiponectin levels have not yet been investigated. We analysed the effect of an acute and euglycaemic elevation of insulin on adiponectin oligomers in 23 healthy individuals. In a subgroup including 11 healthy men, FFAs and TG were acutely elevated by infusion of heparin/lipids over 120 min. Again the effect on circulating adiponectin and its oligomers was investigated. Adiponectin was determined by ELISA, oligomers were detected by nondenaturating Western blot. Acute hyperinsulinaemia resulted in a significant reduction of total adiponectin to 7.74 +/- 0.98 microg/ml (P = 0.004). High molecular weight (HMW) adiponectin did not change (0.80 +/- 0.12 to 0.81 +/- 0.14 microg/ml; P = 0.887), whereas MMW adiponectin decreased from 4.30 +/- 0.51 to 3.78 +/- 0.48 microg/ml (P = 0.005) and LMW adiponectin from 3.63 +/- 0.42 to 3.15 +/- 0.46 microg/ml (P = 0.048). Interestingly, heparin/lipid infusion also reduced circulating adiponectin levels (P = 0.001), which was primarily the result of reduced MMW adiponectin (P = 0.004), whereas LMW and HMW were not significantly affected. The presented data suggest that both, hyperinsulinaemia and hyperlipidaemia, may contribute to low adiponectin levels in states of obesity.
    Clinical Endocrinology 10/2009; 71(4):507-11. · 3.40 Impact Factor
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    ABSTRACT: Fibroblast growth factor (FGF)-21 improves insulin sensitivity and lipid metabolism in obese or diabetic animal models, while human studies revealed increased FGF-21 levels in obesity and type 2 diabetes. Given that FGF-21 has been suggested to be a peroxisome proliferator-activator receptor (PPAR) alpha-dependent regulator of fasting metabolism, we hypothesized that free fatty acids (FFAs), natural agonists of PPARalpha, might modify FGF-21 levels. The effect of fatty acids on FGF-21 was investigated in vitro in HepG2 cells. Within a randomized controlled trial, the effects of elevated FFAs were studied in 21 healthy subjects (13 women and 8 men). Within a clinical trial including 17 individuals, the effect of insulin was analyzed using an hyperinsulinemic-euglycemic clamp and the effect of PPARgamma activation was studied subsequently in a rosiglitazone treatment trial over 8 weeks. Oleate and linoleate increased FGF-21 expression and secretion in a PPARalpha-dependent fashion, as demonstrated by small-interfering RNA-induced PPARalpha knockdown, while palmitate had no effect. In vivo, lipid infusion induced an increase of circulating FGF-21 in humans, and a strong correlation between the change in FGF-21 levels and the change in FFAs was observed. An artificial hyperinsulinemia, which was induced to delineate the potential interaction between elevated FFAs and hyperinsulinemia, revealed that hyperinsulinemia also increased FGF-21 levels in vivo, while rosiglitazone treatment had no effect. The results presented here offer a mechanism explaining the induction of the metabolic regulator FGF-21 in the fasting situation but also in type 2 diabetes and obesity.
    Diabetes 05/2009; 58(7):1532-8. · 7.90 Impact Factor
  • Diabetologie Und Stoffwechsel - DIABETOL STOFFWECHS. 01/2009; 4.
  • Diabetologie Und Stoffwechsel - DIABETOL STOFFWECHS. 01/2009; 4.