Lipid droplet size and location in human skeletal muscle fibers are associated with insulin sensitivity

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  • Joachim Nielsen, Odense Univ Hosp, Odense University Hospital, SDU Muscle Res Cluster, Dept Pathol
  • ,
  • Anders E. Christensen, Univ Southern Denmark, University of Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech
  • ,
  • Birgitte Nellemann
  • ,
  • Britt Christensen

In skeletal muscle, an accumulation of lipid droplets (LDs) in the subsarcolemmal space is associated with insulin resistance, but the underlying mechanism is not clear. We aimed to investigate how the size, number, and location of LDs are associated with insulin sensitivity and muscle fiber types and are regulated by aerobic training and treatment with an erythropoiesis-stimulating agent (ESA) in healthy young untrained men. LD analyses were performed by quantitative transmission electron microscopy, and insulin sensitivity was assessed by a hyperinsulinemic-euglycemic clamp. At baseline, we found that only the diameter (and not the number) of individual subsarcolemmal LDs was negatively associated with insulin sensitivity (R-2= 0.20, P = 0.03, n = 29). Despite 34%: (P = 0.004) fewer LDs, the diameter of individual subsarcolemmal LDs was 20% (P = 0.0004) larger in type 2 fibers than in type 1 fibers. Furthermore, aerobic training decreased the size of subsarcolemmal LDs in the type 2 fibers, and ESA treatment lowered the number of both intermyofibrillar and subsarcolemmal LDs in the type 1 fibers. In conclusion, the size of individual subsarcolemmal LDs may be involved in the mechanism by which LDs are associated with insulin resistance in skeletal muscle.

Original languageEnglish
JournalA J P: Endocrinology and Metabolism (Online)
Volume313
Issue6
Pages (from-to)E721-E730
Number of pages10
ISSN0193-1849
DOIs
Publication statusPublished - Dec 2017

    Research areas

  • intramuscular lipid droplets, insulin sensitivity, transmission electron microscopy, skeletal muscle fiber types, aerobic training, eryhropoietin, HEALTHY-YOUNG MEN, ERYTHROPOIETIN TREATMENT, INTRAMUSCULAR TRIGLYCERIDE, ELECTRON-MICROSCOPY, WEIGHT-LOSS, EXERCISE, RESISTANCE, EXPRESSION, GLYCOGEN, LOCALIZATION

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