Lipid alterations in the skeletal muscle tissues of mice after weight regain by feeding a high-fat diet using nanoflow ultrahigh performance liquid chromatography-tandem mass spectrometry

This study investigated lipid alterations in muscle tissues [gastrocnemius (Gas) and soleus (Sol)] of mice under different diet programs (weight gain, weight maintenance, weight regain, and controls) by nanoflow ultrahigh pressure liquid chromatography-electrospray ionization-tandem mass spectrometry. Since overloaded lipids in the skeletal muscle tissues by excessive fat accumulation are related to insulin resistance leading to type II diabetes mellitus, analysis of lipid alteration in muscle tissues with respect to high-fat diet (HFD) is important to understand obesity related diseases. A total of 345 individual lipid species were identified with their molecular structures, and 184 lipids were quantified by selected reaction monitoring method. Most triacylglycerol (TG) and phosphatidylethanolamine (PE) species displayed a significant (>2-fold, p < 0.01) increase in both the Gas and Sol and to a larger degree in the Gas. However, lipid classes involved in insulin resistance and anti-inflammatory response, including lysophosphatidylcholine (18:0), diacylglycerol (16:0_18:1, 16:0_18:2, and 18:1_18:1), ceramide (d18:1/24:0 and d18:1/24:1), and phosphatidylinositol (18:0/20:4), showed a significant accumulation in the Sol exclusively after HFD treatment. In addition, the lipid profiles were not significantly altered in mice that were fed HFD only for the last 4 weeks (weight gain group), suggesting that consuming HFD in the younger age period can be more effective in the Gas. This study reveals that lipid classes related to insulin resistance accumulated more in the Sol than in the Gas following HFD treatment and the weight regain program perturbed lipid profiles of the Sol to a greater extent than that by the other diet programs, confirming that the Sol tissue is more influenced by HFD than Gas.