| Objective1. To observe the effects of medium chain fatty acids on cholesterol efflux in THP-1 macrophages-derived foam cells.2. To observe the impacts of medium chain triglycerides (MCT) on body fat, blood lipids and reverse cholesterol transport (RCT) and its mechanisms in C57BJ/6L obese mice with hypercholesterolemia.3. To investigate the effects of medium chain triglycerides on body fat, blood lipids and atherosclerosis (AS) and its mechanisms study in C57BJ/6L apolipoprotein E-null mice.Methods1. In the presence of Oμmmol/L,100μmmol/L and 200μmmol/L different fatty acids (C8:0, C10:0, C14:0, C16:0, C18:0, C18:1, C18:2, C18:3) on THP-1 macrophages-derived foam cells riched in 3H-cholesterol, after 24h detected the rate of cholesterol efflux.2. C57BL/6J obese mice with hypercholesterolemia were randomly divided into 3 groups:MCT, LCT, and HFC group.3 months later, RCT was assessed by injecting intraperitoneally 3H-cholesterol labeled RAW264.7 macrophages into the mice. After 72 hours, several tissues were isolated and feces were collected, plasmas lipid profiles were determined by enzymatic method and monitored for the appearance of 3H-tracer in plasma, liver and feces. To evaluate the mRNA expression of ABCA1, SR-BI, CYP7A1, ABCG5/ABCG8 of liver and ABCG5/ABCG8, NPC1L1 of intestine by reverse transcription polymerase chain reaction (RT-PCR) and their protein expression by western-blot.3. Apolipoprotein E-null mice were randomly divided into 2 groups (MCT and LCT group), fed high fat diet with MCT or high fat diet with LCT for 4 months. Body weight, diet intake, body fat mass, Lee’s index, blood lipids and atherosclerotic plaque were measured. The mRNA expression of ABCA1, SR-BI, CYP7A1, ABCG5/ABCG8 of liver and ABCG5/ABCG8, NPC1L1 of intestine evaluated by RT-PCR and their protein expression measured by western-blot.Results1. With the increase of concentration of fatty acids (C8:0, C18:0, C18:1,C18:3) the rate of cholesterol efflux was significantly highter than in control group (P<0.05); At 100p.mmol/L concentration, C18:0 fatty acids decreased the rate of cholesterol efflux more than control group (P< 0.05), and C8:0, C10:0, C16:0, C18:2 fatty acids increased cholesterol efflux were significantly higher than in C18:0, C18:1 fatty acids groups (P<0.05); At 200μmmol/L concentration, C8:0 fatty acids increased the rate of cholesterol efflux was significantly higher than in C10:0, C14:0, C16:0, C18:0, C18:1 and C18:2 fatty acids groups (P<0.05).2. At the end of C57BL/6J mice study:MCT group’body weight, body fat, liver weight, serum levels of TC and Lee’s index were significantly lower than LCT group (P<0.05); No significant differences in diet intake and daily food energy intake between two groups (P>0.05); with no significant difference in serum levels of HDL-C, n-HDL-C, HDL-C/n-HDL-C and TG between two groups (P>0.05); The level of 3H-cholesterol in plasma and liver were much lower in MCT group than in LCT group (P<0.05), while the total 3H-cholesterols in feces in 3 days experiment and at 48h after the injection of 3H-cholesterol labeled RAW264.7 macrophages were significantly higher in MCT group than LCT group (P<0.05); The mRNA and protein expression of ABCA1, ABCG8, CYP7A1 of liver were greater increased and the mRNA expression of ABCA1 of liver was increased and NPC1L1 of intestine was decreased in MCT group than in LCT group(P<0.05).3. Apolipoprotein E-null mice study:MCT group’s body weight of 8 week,12week and 16 week were significantly lower than LCT group (P<0.05); MCT group’s body fat, liver weight, TC and Lee’s index were significantly lower than LCT group (P<0.05); No significant differences in diet intake, daily food energy intake and cholesterol intake between two groups (P>0.05); The serum levels of HDL-C, HDL-C/n-HDL-C of MCT group were significantly higher than that of LCT group (P<0.05); The plaque area of aortic sinus and the ratio of atherosclerotic plaque area/aortic area were significantly lower in MCT group than LCT group (P<0.05); The mRNA expression of ABCA1, ABCG8, CYP7A1 of liver was greater increased and NPC1L1 of intestine was decreased in MCT group than in LCT group(P<0.05). The protein expression of ABCA1, CYP7A1 of liver and ABCG8 of intestine was greater increased and NPC1L1 of intestine was greater decreased in MCT group than in LCT group(P<0.05).Conclusion1. The medium chain fatty acid C8:0 can increase the rate of cholesterol efflux in THP-1 macrophages-derived foam cells.2. MCT can reduce the body weight, body fat, the serum level of TC and promote RCT by up-regulating the mRNA expression of ABCA1, ABCG8, CYP7A1 of liver and decreasing the mRNA expression of NPC1L1 of intestine (P<0.05). MCT also can increase the protein expression of ABCG8, CYP7A1 of liver in C57BL/6J mice with hypercholesterolemia (P<0.05).3. MCT can promote the body weight, body fat, blood lipids and reduce the atherosclerotic plaque by up-regulating the mRNA of ABCA1, ABCG8, CYP7A1 and the protein expression of ABCA1, CYP7A1 of liver. MCT also can decreas the mRNA and protein expression of NPC1L1 and increase the protein expression of ABCG8 of intestine in apolipoprotein E-null mice. |
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