Tissue Specific-Metabolism of Lipids for Ectopic Deposition

Maengkyu Kim

Article

Korean J Obes 2011; 20(3): 99-106

Published online September 1, 2011

Tissue Specific-Metabolism of Lipids for Ectopic Deposition

Maengkyu Kim^*

Author Affiliations

Department of Endocrinology and Metabolism, Sportology Center, School of Medicine, Juntendo University, Tokyo, JAPAN

Abstract

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Abstract
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It is now known that triglyceride accumulates in non-adipose tissues as in liver, skeletal muscle, pancreas, and heart. Excessive accumulation of ectopic fat causes abnormal pathophysiological changes in function and mechanism within the organ. For example, excessive ectopic fat accumulation within the hepatic cells and skeletal muscle cells results in insulin resistance by
inducing impairment of information transport of insulin.
Ectopic fats accumulated within the cardiac epicardium and cardiac cells are associated with insulin resistance and systolic dysfunction. The ectopic fat content assessed by biopsy, echocardiograph, and proton magnetic resonance spectroscopy correlates closely with specific tissues and overall systemic insulin resistance. Ectopic fat is considered a better and a stronger predictor of insulin resistance than visceral adipose tissue. Therefore, increased triglycerides in liver, pancreas, skeletal muscle, and heart may be a part of metabolic abnormality leading
to insulin resistance, and subsequent development of Type 2 diabetes mellitus. Recent studies showed that exercise, diet, and medication, decreased insulin resistance by changing the ectopic fat contents. According to these studies, the mechanisms by which exercise, diet, and medication influence lipogenic gene expressions toward intramyocellular fat contents are different, in particular,
lipid metabolites including diacylglycerols and ceramides.
Prevention and treatment of metabolic disease may be expected in the near future with the development of novel biochemical markers that have specific correlation to ectopic fat tissues.

Keywords: Ectopic fat, Obesity, Metabolism, Exercise, Diet

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Fig. 1. Metabolic abnormality caused by increased partitioning of triglyceride into ectopic tissues.

Fig. 2. Scheme of mechanism of the effect of exercise against fatty acid-induced insulin resistance on IMCL regulation.

Fig. 3. IMTG regulation after exercise/diet interventions.

Fig. 4. MR imaging with 1H-MRS localization and corresponding spectrum in vivo. A, MR imaging acquired from short axis. B, MR imaging acquired from long axis. C, MR spectroscopy spectrum derived from a 20 × 10 × 10-mm (2 cc) voxel of an cardiac septum of A and B imaging. The water, creatine, and lipid resonate 4.7, 3.0, 1.3 ppm, respectively (from CardioFunction Study at Juntendo Univ.).

References

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