Physical Inactivity Differentially Alters Dietary Oleate and Palmitate Trafficking
- Audrey Bergouignan1,
- Guy Trudel2,
- Chantal Simon3,
- Angèle Chopard4,
- Dale A. Schoeller5,
- Iman Momken1,
- Susanne B. Votruba6,
- Michel Desage7,
- Graham C. Burdge8,
- Guillemette Gauquelin-Koch9,
- Sylvie Normand7 and
- Stéphane Blanc1
- 1Department of Ecology, Physiology, and Ethology, Hubert Curien Pluridisciplinary Institute, Louis Pasteur University, UMR7178 Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
- 2Department of Medicine, Bone and Joint Research Laboratory, University of Ottawa, Ottawa, Canada
- 3Nutrition Department, Hautepierre Hospital, Louis Pasteur University, Strasbourg, France
- 4Laboratory of Physiology of Adaptations, Nice Sophia Antipolis University, Nice, France, and Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
- 5Department of Nutritional Sciences, University of Wisconsin, Madison Wisconsin
- 6Obesity and Diabetes Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona
- 7Human Nutrition Research Center of Rhône Alpes (CRNHL), Laennec Medicine Faculty, Lyon, France
- 8Institute of Human Nutrition, University of Southampton, Southampton, U.K
- 9French Space Agency (CNES), Paris, France
- Corresponding author: Stéphane Blanc, stephane.blanc{at}c-strasbourg.fr
Abstract
OBJECTIVE— Obesity and diabetes are characterized by the incapacity to use fat as fuel. We hypothesized that this reduced fat oxidation is secondary to a sedentary lifestyle.
RESEARCH DESIGN AND METHODS— We investigated the effect of a 2-month bed rest on the dietary oleate and palmitate trafficking in lean women (control group, n = 8) and the effect of concomitant resistance/aerobic exercise training as a countermeasure (exercise group, n = 8). Trafficking of stable isotope–labeled dietary fats was combined with muscle gene expression and magnetic resonance imaging–derived muscle fat content analyses.
RESULTS— In the control group, bed rest increased the cumulative [1-13C]oleate and [d31]palmitate appearance in triglycerides (37%, P = 0.009, and 34%, P = 0.016, respectively) and nonesterified fatty acids (NEFAs) (37%, P = 0.038, and 38%, P = 0.002) and decreased muscle lipoprotein lipase (P = 0.043) and fatty acid translocase CD36 (P = 0.043) mRNA expressions. Plasma NEFA-to-triglyceride ratios for [1-13C]oleate and [d31]palmitate remained unchanged, suggesting that the same proportion of tracers enters the peripheral tissues after bed rest. Bed rest did not affect [1-13C]oleate oxidation but decreased [d31]palmitate oxidation by −8.2 ± 4.9% (P < 0.0001). Despite a decreased spontaneous energy intake and a reduction of 1.9 ± 0.3 kg (P = 0.001) in fat mass, exercise training did not mitigate these alterations but partially maintained fat-free mass, insulin sensitivity, and total lipid oxidation in fasting and fed states. In both groups, muscle fat content increased by 2.7% after bed rest and negatively correlated with the reduction in [d31]palmitate oxidation (r2 = 0.48, P = 0.003).
CONCLUSIONS— While saturated and monounsaturated fats have similar plasma trafficking and clearance, physical inactivity affects the partitioning of saturated fats toward storage, likely leading to an accumulation of palmitate in muscle fat.
Footnotes
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Published ahead of print at http://diabetes.diabetesjournals.org on 18 November 2008.
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- Accepted November 14, 2008.
- Received February 22, 2008.
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