Dietary walnut reduces hepatic triglyceride content in high-fat-fed mice via modulation of hepatic fatty acid metabolism and adipose tissue inflammation

Youngshim Choi, Mohamed A. Abdelmegeed, Mohammed Akbar, Byoung Joon Song

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, we evaluated the protective effects of dietary walnuts on high-fat diet (HFD)-induced fatty liver and studied the underlying mechanisms. Male C57BL/6J mice were fed either a regular rodent chow or HFD (45% energy-derived) with or without walnuts (21.5% energy-derived) for 20 weeks. Walnut supplementation did not change HFD-induced increase in body weight or visceral fat mass. However, dietary walnuts significantly decreased the amounts of hepatic triglyceride (TG) observed in HFD-fed mice. The addition of walnuts significantly altered the levels of proteins, involved in the hepatic lipid homeostasis, including AMP-activated protein kinase, fatty acid synthase and peroxisome proliferator-activated receptor-α. Since adipocyte inflammation and apoptosis are reportedly important in regulating hepatic fat accumulation, we also evaluated the protective effects of walnuts on adipose tissue injury. Real-time polymerase chain reaction results revealed that adipose tissues isolated from mice fed the HFD. +. walnut diets showed significantly decreased levels of macrophage infiltration with suppressed expression of proinflammatory genes compared to those significantly elevated in mice fed HFD alone. These improvements also coincided with reduction of HFD-induced apoptosis of adipocytes by dietary walnuts. However, the supplemented walnuts did not significantly alter HFD-induced peripheral glucose intolerance or insulin resistance despite a trend of improvement. Collectively, these results demonstrate that the protective effects of walnuts against HFD-induced hepatic TG accumulation in mice are mediated, at least partially, by modulating the key proteins in hepatic lipid homeostasis and suppression of the genes related to adipose tissue inflammation and macrophage infiltration as well as prevention of adipocyte apoptosis.

Original languageEnglish (US)
Pages (from-to)116-125
Number of pages10
JournalJournal of Nutritional Biochemistry
Volume30
DOIs
StatePublished - Apr 1 2016
Externally publishedYes

Keywords

  • Adipose tissue
  • High-fat diet
  • Inflammation
  • Liver
  • Steatosis
  • Triglyceride
  • Walnut

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Molecular Biology
  • Nutrition and Dietetics
  • Clinical Biochemistry

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