Metabolomics in Hind limb and Heart Muscle of a Mouse Model after a High-fat Diet

Abstract

Objective: Dysregulation of FA metabolism in heart muscle is a major problem associated with the metabolic syndrome. Methods: C57Bl/6 mice were fed for 40 days a high-fat diet (+0.25% cholesterol 45% energy from bovine lard). High Performance Thin Layer Chromatography (HPTLC) was used to measure Triacylglycerol’s (TG) and Free Cholesterol (FCh) in hearts and hind limb muscle of mice. With LC-MS techniques we measured Cholesterol esters (ChE), lysophosphatidyl-cholines (LPC), phosphatidylcholine (PC), sphingomyelin (SPM) and Triacylglycerol’s (TG) in hind limb and heart muscle after 40 days of a fatty diet. Results: This study was designed to give more insight in the lipid composition of the heart muscle in comparison to hind limb muscle. Only in the heart muscle cholesterol esters (ChE) were observed. This was confirmed with LC-MS techniques. Especially the 20:3-ChE are significantly increased in the fatty heart with 1317%. The LC-MS techniques gave no clear picture for Lysophosphatidyl-cholines (LPC), Sphingomyelin (SPM) in hind limb and heart muscle after 40 days of a fatty diet. Only for Phosphatidylcholine (PC) the most remarkable observation was that 36:1-PC rises in heart muscle with 4000%. Twenty-three triglycerides were measured in hind limb muscle but no effect was observed after 40 days of high-fat diet. In contrast, in the heart muscle four types of TG increased dramatically after a 40 days fatty diet ( 54:2-TG (+394%), 54:3-TG (+452%), 56:3-TG (+297%) and 56:5-TG (+213%). Based on Principal Component Analysis with different lipid compounds like LPC, SPM, TG, PC and ChE, a separation can be made for high-fat diet fed animals and control diet fed animals both for hind limb muscle and heart muscle. After elimination of the TG and the ChE and a new PCA run we see that four groups can be clearly separated: Control-heart, Fat-heart, Control-hind limb muscle and Fat-hind limb muscle. Conclusions: These analyses provide potential biomarkers for the diagnosis of diet-induced lipid accumulation in heart and hind-limb muscle tissue.