Vitamin D insufficiency exacerbates adipose tissue macrophage infiltration and decreases AMPK/SIRT1 activity in obese rats

Eugene Chang, Yangha Kim

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59 Scopus citations

Abstract

Obesity is recognized as a state of chronic low-grade systemic inflammation due to adipose tissue macrophage infiltration and production of proinflammatory adipokines. Decreased vitamin D status is associated with obesity. The specific aim of the present study is to investigate the effects of vitamin D on obesity-induced adipose tissue inflammation. Male Sprague-Dawley rats were randomized and fed a normal diet (NOR, 1000 IU vitamin D/kg diet), a 45% high-fat diet (HF, 1000 IU vitamin D/kg diet), or a 45% high-fat diet containing 25 IU vitamin D/kg diet (HF+LVD) for 12 weeks. The vitamin D-insufficient diet (HF+LVD) led to vitamin D inadequacy as determined by serum 25(OH)D level, 68.56 ± 7.97 nmol/L. The HF+LVD group exacerbated HF-increased adipocyte size, adipogenic gene expression of PPARγ, adipose tissue macrophage recruitment, and proinflammatory cytokine IL-6 and TNFα levels in epididymal white adipose tissue. In addition, vitamin D insufficiency significantly decreased mRNA levels of β-oxidation-related genes such as CPT1α, PGC1α, PPARα, VLCAD, LCAD, MCAD, and UCP1. Moreover, significant decrements of SIRT1 and AMPK activity were noted in obese rats fed with a vitamin D-insufficient diet. The observed deleterious effects of vitamin D insufficiency on adipose tissue expansion, immune cell infiltration and inflammatory status suggest vitamin D plays a beneficial role in adipocyte metabolic metabolism and obesity progression. SIRT1 and AMPK activity may play a role in the mechanism of vitamin D action.

Original languageEnglish
Article number338
JournalNutrients
Volume9
Issue number4
DOIs
StatePublished - Apr 2017

Bibliographical note

Funding Information:
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2014R1A1A3050953) and Brain Korea 21 Plus (22A20130012143).

Publisher Copyright:
© 2017 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Adenosine monophosphate-activated protein kinase (AMPK)
  • Adipose tissue macrophage infiltration
  • Obesity
  • Sirtulin 1 (SIRT1)
  • Vitamin D

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