Germ-free C57BL/6J mice are resistant to high-fat-diet-induced insulin resistance and have altered cholesterol metabolism
2010
Rabot, Sylvie | Membrez, Mathieu | Bruneau, Aurelia | Gerard, Philippe | Harach, Taoufiq | Moser, Mireille | Raymond, Frederic | Mansourian, Robert | Chou, Chieh J. | MICrobiologie de l'ALImentation au Service de la Santé (MICALIS) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | Dept Nutr & Hlth ; Nestlé Suisse | Dept Bioanalyt Sci ; Nestlé Suisse | Nestec S.A.
Recent studies showed that germ-free (GF) mice are resistant to obesity when consuming a high-fat, high-carbohydrate Western diet. However, it remains unclear what mechanisms are involved in the antiobesity phenotype and whether GF mice develop insulin resistance and dyslipidemia with high-fat (HF) feeding. In the present study, we compared the metabolic consequences of HF feeding on GF and conventional (conv) C57BL/6J mice. GF mice consumed fewer calories, excreted more fecal lipids, and weighed significantly less than conv mice. GF/HF animals also showed enhanced insulin sensitivity with improved glucose tolerance, reduced fasting and nonfasting insulinemia, and increased phospho-Akt((Ser-473)) in adipose tissue. In association with enhanced insulin sensitivity, GF/HF mice had reduced plasma TNF-alpha and total serum amyloid A concentrations. Reduced hyperchole-sterolemia, a moderate accretion of hepatic cholesterol, and an increase in fecal cholesterol excretion suggest an altered cholesterol metabolism in GF/HF mice. Pronounced nucleus SREBP2 proteins and up-regulation of cholesterol biosynthesis genes indicate that enhanced cholesterol biosynthesis contributed to the cholesterol homeostasis in GF/HF mice. Our results demonstrate that fewer calorie consumption and increased lipid excretion contributed to the obesity-resistant phenotype of GF/HF mice and reveal that insulin sensitivity and cholesterol metabolism are metabolic targets influenced by the gut microbiota.-Rabot, S., Membrez, M., Bruneau, A., Gerard, P., Harach, T., Moser, M., Raymond, F., Mansourian, R., Chou. C. J. Germ-free C57BL/6J mice are resistant to high-fat-diet-induced insulin resistance and have altered cholesterol metabolism. FASEB J. 24, 4948-4959 (2010). www.fasebj.org
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