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

Joachim Nielsen, Anders E Christensen, Birgitte Nellemann, Britt Christensen

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Abstract

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 males. 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 (R2 = 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 2fibers, and ESA treatment lowered the number of both intermyofibrillar and subsarcolemmal LDs in the type 1fibers. 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
JournalAmerican Journal of Physiology: Endocrinology and Metabolism
Volume313
Issue number6
Pages (from-to)E721-E730
ISSN0193-1849
DOIs
Publication statusPublished - 2017

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Insulin Resistance
Hematinics
Skeletal Muscle
Lipid Droplets
Glucose Clamp Technique
Transmission Electron Microscopy
Muscles

Keywords

  • Journal Article

Cite this

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title = "Lipid droplet size and location in human skeletal muscle fibers are associated with insulin sensitivity",
abstract = "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 males. 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 (R2 = 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 2fibers, and ESA treatment lowered the number of both intermyofibrillar and subsarcolemmal LDs in the type 1fibers. 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.",
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year = "2017",
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Lipid droplet size and location in human skeletal muscle fibers are associated with insulin sensitivity. / Nielsen, Joachim; Christensen, Anders E; Nellemann, Birgitte; Christensen, Britt.

In: American Journal of Physiology: Endocrinology and Metabolism, Vol. 313, No. 6, 2017, p. E721-E730.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Lipid droplet size and location in human skeletal muscle fibers are associated with insulin sensitivity

AU - Nielsen, Joachim

AU - Christensen, Anders E

AU - Nellemann, Birgitte

AU - Christensen, Britt

N1 - Copyright © 2017, American Journal of Physiology-Endocrinology and Metabolism.

PY - 2017

Y1 - 2017

N2 - 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 males. 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 (R2 = 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 2fibers, and ESA treatment lowered the number of both intermyofibrillar and subsarcolemmal LDs in the type 1fibers. 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.

AB - 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 males. 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 (R2 = 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 2fibers, and ESA treatment lowered the number of both intermyofibrillar and subsarcolemmal LDs in the type 1fibers. 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.

KW - Journal Article

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DO - 10.1152/ajpendo.00062.2017

M3 - Journal article

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JF - American Journal of Physiology: Endocrinology and Metabolism

SN - 0193-1849

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