Effects of Different High Fat Diets on FABP Content in Rat Skeletal Muscles

Abstract

Long-term feeding of high fat diet increases both oxidative enzymes in skeletal muscle and endurance capacity in rats, whereas it is well-known to cause obesity. PURPOSE: The purpose of this study was to examine the effects of high fat diet containing long-chain diacylglycerol (DAG), medium-chain triacylglycerol (MTG) or long-chain triacylglycerol (TAG) on oxidative enzyme activities and fatty acid binding protein (FABP) contents in rat skeletal muscles. METHODS: Male Wistar rats, 5 weeks old, were assigned to 4 groups; low fat diet (LF; n=6, 12% calories as fat), TAG high fat diet (n=6, 60% calories as fat), DAG high fat diet (n=6, 60% calories as fat) and MTG high fat diet (n=7, 60% calories as fat) groups. Animals were fed their diets and water ad libitum for 5 weeks. Citrate synthase (CS) activity was measured by a spectrophotometric assay, and FABP content was measured with an ELISA kit. RESULTS: Epidydimal fat pad was much smaller in MTG group than in HTG and DAG groups (P<0.05). TAG and MTG groups were increased CS activity (TAG, 40±2.5 mol·min-1·g-1; MTG, 44±2.8 mol·min-1·g-1) in soleus muscle (Sol) compared with LF (35±4.1 mol·min-1·g-1) group (p < 0.01). FABP contents of Sol and red gastrocnemius muscle (Gas) were significantly higher in TAG (Sol, 62 ±7.3; red Gas, 59±21.8 ng/ml) and DAG (Sol, 58±9.1; red Gas, 51±5.8 ng/ml) groups than in MTG (Sol, 28±2.8; red Gas, 28±6.2 ng/ml) group (p < 0.05). On the other hand, FABP contents of white Gas were, albeit small, significantly higher in TAG (1.8±0.3 ng/ml), DAG (2.4±0.3 ng/ml) and MTG (1.5±0.2 ng/ml) groups than in LF (0.3±0.1 ng/ml) group (p < 0.05). CONCLUSION: Thus, the 5-week-feeding of DAG high fat diet increased FABP content in Sol and red/white Gas, and also the MTG high fat diet increased both FABP content in white Gas and oxidative enzymes without fat accumulation, suggesting that "MTG plus DAG" high fat diet may enhance fat metabolism and exercise performance without obesity.