Supplementary Material for: Chronic Consumption of trans-Fat-Rich Diet Increases Hepatic Cholesterol Levels and Impairs Muscle Insulin Sensitivity without Leading to Hepatic Steatosis and Hypertriglyceridemia in Female Fischer Rats

Background: The impact of industrial trans fatty acids (TFAs) on lipid metabolism and health remains elusive. Methods: We compared the effect of long-term (52 weeks) ingestion of 10% partially hydrogenated vegetable oil, providing 4.2% of total energy from TFAs, on hepatic lipid metabolism and muscle insulin sensitivity in weanling female Fischer rats with that of palmolein (monounsaturated fatty acid, MUFA), sunflower (n–6 polyunsaturated fatty acid, PUFA), and a blend of sunflower and fish oil (n–3 PUFA). Results: The proportion of plasma high-density lipoprotein cholesterol in total cholesterol and reverse cholesterol transport-associated protein expressions were similar in all the groups. Despite higher lipogenic-pathway protein levels, steatosis or hypertriglyceridemia was not observed in TFA-fed rats. Though TFA ingestion had no effect on fasting plasma glucose, insulin levels or oral glucose tolerance, it significantly decreased muscle insulin-stimulated glucose uptake as compared to PUFAs. Further, TFA ingestion increased adipose tissue retinol-binding protein 4 mRNA as compared to PUFAs (n–6 or n–3). The effects of MUFA (oleic acid) on all these parameters were comparable to those observed for TFAs. Conclusions: Compared to PUFA-rich diets, chronic consumption of a TFA-rich diet did not lead to steatosis or hypertriglyceridemia; however, it significantly impaired muscle insulin sensitivity, while no changes were found in the oral glucose tolerance test.