Differential effects of low-fat and high-fat diets on fed-state hepatic triacylglycerol secretion, hepatic fatty acid profiles, and DGAT-1 protein expression in obese-prone Sprague-Dawley rats

Timothy D. Heden, E. Matthew Morris, Monica L. Kearney, Tzu Wen Liu, Young Min Park, Jill A. Kanaley, John P. Thyfault

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The purpose of this study was to compare the effects of short-term low-fat (LF) and high-fat (HF) diets on fed-state hepatic triacylglycerol (TAG) secretion, the content of proteins involved in TAG assembly and secretion, fatty acid oxidation (FAO), and the fatty acid profile of stored TAG. Using selectively bred obese-prone Sprague-Dawley rats, we directly measured fed-state hepatic TAG secretion, using Tyloxapol (a lipoprotein lipase inhibitor) and a standardized oral mixed meal (45% carbohydrate, 40% fat, 15% protein) bolus in animals fed a HF or LF diet for 2 weeks, after which the rats were maintained on their respective diet for 1 week (washout) prior to the liver being excised to measure protein content, FAO, and TAG fatty acid profiles. Hepatic DGAT-1 protein expression was ~27% lower in HF- than in LF-fed animals (p < 0.05); the protein expression of all other molecules was similar in the 2 diets. The fed-state hepatic TAG secretion rate was ~39% lower (p < 0.05) in HF- (4.62 ± 0.18 mmol·h-1) than in LF- (7.60 ± 0.57 mmol·h-1) fed animals. Hepatic TAG content was ~2-fold higher (p < 0.05) in HF- (1.07 ± 0.15 nmol·g-1 tissue) than in LF- (0.50 ± 0.16 nmol·g-1 tissue) fed animals. In addition, the fatty acid profile of liver TAG in HF-fed animals closely resembled the diet, whereas in LF-fed animals, the fatty acid profile consisted of mostly de novo synthesized fatty acids. FAO was not altered by diet. LF and HF diets differentially alter fed-state hepatic TAG secretion, hepatic fatty acid profiles, and DGAT-1 protein expression.

Original languageEnglish (US)
Pages (from-to)472-479
Number of pages8
JournalApplied Physiology, Nutrition and Metabolism
Volume39
Issue number4
DOIs
StatePublished - 2014
Externally publishedYes

Keywords

  • Diet composition
  • Fatty acids
  • Lipid metabolism
  • Liver
  • Obese prone
  • Very-low-density lipoprotein

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