Metabolic responses to high-fat diets rich in n-3 or n-6 long-chain polyunsaturated fatty acids in mice selected for either high body weight or leanness explain different health outcomes
1 Leibniz Institute for Farm Animal Biology, Department of Muscle Biology and Growth, 18196 Dummerstorf, W.-Stahl-Allee 2, Germany
2 Institute of Food, Nutrition and Human Health, Massey University, Albany Campus, Private Bag 102 904, North Shore Mail Centre, Auckland, New Zealand
3 School of Biological Sciences, Faculty of Science, University of Auckland, Auckland, New Zealand
4 Department of Physiology, University of Veterinary Medicine Hannover, 30173 Hannover, Germany
5 Discipline of Physiology, School of Medical Sciences, The University of Adelaide, Adelaide, Australia
6 Leibniz Institute for Farm Animal Biology, Department of Genetic and Biometry, 18196 Dummerstorf, W.-Stahl-Allee 2, Germany
7 Leibniz Institute for Farm Animal Biology, Department of Reproductive Biology, 18196 Dummerstorf, W.-Stahl-Allee 2, Germany
Nutrition & Metabolism 2011, 8:56 doi:10.1186/1743-7075-8-56Published: 11 August 2011
Increasing evidence suggests that diets high in polyunsaturated fatty acids (PUFA) confer health benefits by improving insulin sensitivity and lipid metabolism in liver, muscle and adipose tissue.
The present study investigates metabolic responses in two different lines of mice either selected for high body weight (DU6) leading to rapid obesity development, or selected for high treadmill performance (DUhTP) leading to a lean phenotype. At 29 days of age the mice were fed standard chow (7.2% fat, 25.7% protein), or a high-fat diet rich in n-3 PUFA (n-3 HFD, 27.7% fat, 19% protein) or a high-fat diet rich in n-6 PUFA (n-6 HFD, 27.7% fat, 18.6% protein) for 8 weeks. The aim of the study was to determine the effect of these PUFA-rich high-fat diets on the fatty acid profile and on the protein expression of key components of insulin signalling pathways.
Plasma concentrations of leptin and insulin were higher in DU6 in comparison with DUhTP mice. The high-fat diets stimulated a strong increase in leptin levels and body fat only in DU6 mice. Muscle and liver fatty acid composition were clearly changed by dietary lipid composition. In both lines of mice n-3 HFD feeding significantly reduced the hepatic insulin receptor β protein concentration which may explain decreased insulin action in liver. In contrast, protein kinase C ζ expression increased strongly in abdominal fat of n-3 HFD fed DUhTP mice, indicating enhanced insulin sensitivity in adipose tissue.
A diet high in n-3 PUFA may facilitate a shift from fuel deposition in liver to fuel storage as fat in adipose tissue in mice. Tissue specific changes in insulin sensitivity may describe, at least in part, the health improving properties of dietary n-3 PUFA. However, important genotype-diet interactions may explain why such diets have little effect in some population groups.