Correlation between insulin resistance and intramyocellular lipid levels in rats

• Published in: Magnetic resonance in medicine Vol. 53; no. 6; pp. 1275 - 1282
• Main Authors: Kuhlmann, J., Neumann-Haefelin, C., Belz, U., Kramer, W., Juretschke, H.-P., Herling, A. W.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.06.2005
• Subjects: Adipose Tissue; Analysis of Variance; Animals; Biomarkers - analysis; Female; glucose clamp; Glucose Clamp Technique; Insulin Resistance; insulin sensitivity indices; intramyocellular lipids; Lipids - analysis; Magnetic Resonance Spectroscopy - methods; Male; Muscle, Skeletal - chemistry; Obesity - physiopathology; rat models; Rats; Rats, Wistar; Statistics, Nonparametric
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.20501

Increased intramyocellular lipid (IMCL) content has been proposed as biomarker for insulin resistance (IR). An inverse correlation between IMCL and insulin sensitivity (IS) was found in nonathletic humans, whereas in animal models only a few validation studies have been performed. The aim of this study was to investigate the interrelation between IS indices determined by the glucose clamp technique (glucose disposal (GD), exogenous glucose infusion rates (GIR)) and IMCL content in the tibialis (TIB) and the soleus (SOL) muscle obtained by magnetic resonance spectroscopy in different rat models of IR. Diet‐induced insulin‐resistant Wistar rats as well as genetic disease models (ZDF rats) were used. In both muscles, elevated IMCL correlated with an impaired IS in all models of IR. The correlation of IMCL with both parameters for IS was comparable in TIB and SOL. The best fit between IMCL and IS was obtained using TIB and GIR data (r = −0.69, P < 0.001). Diabetic male ZDF rats exhibited comparatively low IMCL levels due to their catabolic state: exclusion of this group improved r. In summary, IMCL, especially in TIB, is a valid biomarker for IS in various rat models of IR with the advantage of a fast repeatable noninvasive measurement in individual animals. Magn Reson Med 53:1275–1282, 2005. © 2005 Wiley‐Liss, Inc.