title: Effects of acute exercise on lipid content and dietary lipid uptake in liver and skeletal muscle of lean and diabetic rats.
abstract: Insulin resistance is associated with ectopic lipid accumulation. Physical activity improves insulin sensitivity, but the impact of exercise on lipid handling in insulin-resistant tissues remains to be elucidated. The present study characterizes the effects of acute exercise on lipid content and dietary lipid partitioning in liver and skeletal muscle of lean and diabetic rats by use of magnetic resonance spectroscopy (MRS). After baseline measurements, rats were randomized to exercise or no-exercise groups. A subset of animals was subjected to MRS directly after 1 h of treadmill running for measurement of total intrahepatocellular lipid (IHCL) and intramyocellular lipid (IMCL) content (n=7 lean and diabetic rats). The other animals were administered 13C-labeled lipids orally after treadmill visit (with or without exercise) followed by MRS measurements after 4 and 24 h to determine the 13C enrichment of IHCL and IMCL (n=8 per group). Total IHCL and IMCL content were fivefold higher in diabetic vs. lean rats (P<0.001). Exercise did not significantly affect IHCL content but reduced IMCL by 25±7 and 33±4% in lean and diabetic rats (P<0.05), respectively. Uptake of dietary lipids in liver and muscle was 2.3-fold greater in diabetic vs. lean rats (P<0.05). Prior exercise did not significantly modulate dietary lipid uptake into muscle, but in liver of both lean and diabetic rats, lipid uptake was 44% reduced after acute exercise (P<0.05). In conclusion, IMCL but not IHCL represents a viable substrate source during exercise in both lean and diabetic rats, and exercise differentially affects dietary lipid uptake in muscle and liver.
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; The Netherlands Consortium for Systems Biology, Den Haag, The Netherlands;
authors.forename: Sharon
authors.initials: S
authors.lastname: Janssens
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands;
authors.forename: Richard A M
authors.initials: RA
authors.lastname: Jonkers
authors.affiliation: Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; and Department of Laboratory Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Albert K
authors.initials: AK
authors.lastname: Groen
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands;
authors.forename: Klaas
authors.initials: K
authors.lastname: Nicolay
authors.affiliation: NUTRIM, School for Nutrition, Toxicology and Metabolism, Department of Human Movement Sciences, Maastricht University Medical Centre+, Maastricht, The Netherlands;
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
authors.affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; j.j.prompers@tue.nl.
authors.forename: Jeanine J
authors.initials: JJ
authors.lastname: Prompers
mesh_terms: D065567:Absorption, Physiological; D000818:Animals; D001786:Blood Glucose; D002247:Carbon Isotopes; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D004041:Dietary Fats / Q000378:metabolism*; D004734:Energy Metabolism; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008055:Lipids / Q000097:blood; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009043:Motor Activity; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000150:complications; D009929:Organ Size; D009928:Organ Specificity; D011897:Random Allocation; D011924:Rats, Zucker
chemical_list: D001786:Blood Glucose; D002247:Carbon Isotopes; D004041:Dietary Fats; D008055:Lipids
keywords: diabetes; exercise; lipid metabolism; liver; skeletal muscle