[The effect of exercise on platelet-activating factor metabolism in the livers of rats fed high-fat diet].

This paper aimed to investigate the effects of exercise on hepatic platelet-activating factor (PAF) metabolism in rats fed a high-fat diet. Thirty-two male Sprague-Dawley (SD) rats were divided into control group (C), high-fat diet group (H), exercise group (EC), and high-fat diet+exercise group (EH). Serum lipids, glucose, insulin and markers of hepatic injury after a 16-week dietary and/or exercise intervention (60 min/day, 6 times/week) were measured by biochemical analysis; liver lipidomic profiles were analyzed by liquid chromatograph-mass spectrometer (LC-MS). Gene and protein expression of enzymes related to PAF metabolism were determined by qPCR and Western blot respectively. The results showed that high-fat diet feeding significantly increased the levels of low-density lipoprotein-cholesterol (LDL-C) and liver injury markers including purine nucleoside phosphorylase (PNP) and malondialdehyde (MDA) in rats, which were decreased by exercise. Furthermore, high-fat diet feeding significantly increased the hepatic PAF content, which was also attenuated by exercise. In addition, although high-fat diet treatment resulted in an increase in the expression of both PAF synthetase (PAF-CPT and PLA2) and hydrolase (Lp-PLA2 and PAF-AH(II)), induction of PAF synthetase was much greater than that of PAF hydrolase. While exercise increased the expression of Lp-PLA2 and PAF-AH(II) and decreased the expression of PAF-CPT and PLA2, key PAF synthesizing enzymes. In conclusion, high-fat diet-induced increase in hepatic PAF content is mainly due to the increase of its pathological synthesis at the translational level. Exercise reduces hepatic PAF content in high-fat fed rats by increasing PAF hydrolysis and decreasing its synthesis.

Endurance Training Counteracts the High-Fat Diet-Induced Profiling Changes of ω-3 Polyunsaturated Fatty Acids in Skeletal Muscle of Middle-Aged Rats.

PURPOSE: To investigate the effects of endurance training on the content of ω-3 polyunsaturated fatty acids (PUFAs) and their distribution among lipid classes in skeletal muscle in middle aged, high-fat diet fed rats. METHOD: Thirty 10-month old male Sprague Dawley (SD) rats were assigned to four groups. Two groups of rats remained sedentary and were fed chow diet (C group), or high-fat diet (H group), respectively. The other two groups of rats were subjected to endurance training while maintaining their chow diet (EC group), or high-fat diet (EH group). After 16 weeks endurance training and/or diet intervention, the content of ω-3 PUFAs and ω-3 PUFA-containing lipids in rat soleus muscle were analyzed by lipidomics. RESULTS: Rats fed a high-fat diet exhibited decreased overall amount of ω-3 PUFAs in soleus muscle, while endurance training preserved the total amount of ω-3 PUFAs. Both the endurance training and high-fat diet alone changed the profiles of ω-3 PUFAs in different lipid classes. Specifically, the amount of triacylglycerol (TG), lysophosphatidylcholine (LPC), phosphatidylcholine (PC), and phosphatidylglycerol (PG) containing ω-3 PUFAs in soleus muscle was increased by endurance training, but the amount of lysophosphatidylenthanol (LPE), lysophosphatidylinositol (LPI), lysophosphatidylserine (LPS), cardiolipin (CL), phosphatidic acid (PA), and phosphatidylinositol (PI) was decreased. The high-fat diet induced a decrease of ω-3 PUFAs in TG, LPE, LPS, CL, platelet activating factor (PAF), PC, phosphatidylethanolamine (PE), and phosphatidylserine (PS), and an increase in LPC, LPI, PA, and PG. In addition, the effects of the endurance training on ω-3 PUFAs in skeletal muscle was also evident in high-fat diets fed rats, which counteracts the profiling changes caused by high-fat diet feeding. CONCLUSION: The beneficial effects of endurance training on skeletal muscle may be achieved to some extent through recovering the content of ω-3 PUFAs that has been decreased by high-fat diet feeding.