Effects of vitamin D on insulin resistance and myosteatosis in diet-induced obese mice

PLoS One. 2018 Jan 17;13(1):e0189707. doi: 10.1371/journal.pone.0189707. eCollection 2018.

Abstract

Epidemiological studies pointed out to a strong association between vitamin D deficiency and type 2 diabetes prevalence. However, the role of vitamin D supplementation in the skeletal muscle, a tissue that play a crucial role in the maintenance of glucose homeostasis, has been scarcely investigated so far. On this basis, this study aimed to evaluate the effect of vitamin D supplementation in a murine model of diet-induced insulin resistance with particular attention to the effects evoked on the skeletal muscle. Male C57BL/6J mice (n = 40) were fed with a control or a High Fat-High Sugar (HFHS) diet for 4 months. Subsets of animals were treated for 2 months with vitamin D (7 μg·kg-1, i.p. three times/week). HFHS diet induced body weight increase, hyperglycemia and impaired glucose tolerance. HFHS animals showed an impaired insulin signaling and a marked fat accumulation in the skeletal muscle. Vitamin D reduced body weight and improved systemic glucose tolerance. In addition, vitamin D restored the impaired muscle insulin signaling and reverted myosteatosis evoked by the diet. These effects were associated to decreased activation of NF-κB and lower levels of TNF-alpha. Consistently, a significantly decreased activation of the SCAP/SREBP lipogenic pathway and lower levels of CML protein adducts and RAGE expression were observed in skeletal muscle of animals treated with vitamin D. Collectively, these data indicate that vitamin D-induced selective inhibition of signaling pathways (including NF-κB, SCAP/SREBP and CML/RAGE cascades) within the skeletal muscle significantly contributed to the beneficial effects of vitamin D supplementation against diet-induced metabolic derangements.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Diet, High-Fat
  • Dietary Carbohydrates / administration & dosage
  • Glucose Tolerance Test
  • Insulin / metabolism
  • Insulin Resistance*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Obese
  • Muscle, Skeletal / metabolism
  • Muscular Diseases / metabolism
  • Muscular Diseases / prevention & control*
  • Signal Transduction
  • Vitamin D / blood
  • Vitamin D / pharmacology*

Substances

  • Dietary Carbohydrates
  • Insulin
  • Vitamin D

Grants and funding

This work was supported and funded by the University of Turin (Ricerca Locale 2015) to Elisa Benetti.