The Study On The Changes Of Oxidized Low-density Lipoprotein, Paraoxonase1 In Fasting And Postprandial States By Fat-loading And The Relationship Between Ox-LDL, PON1 And Atherosclerosis

Objective:To study the changes of ox-LDL and PON1 in fasting state and several postprandial time points, and to explore its relationship with atherosclerosis.Methods:Select 10 healthy New Zealand male rabbits with weighing 2.4kg-3.0kg.They were fed one week with normal diet adaptively at first. Then, they were fed with high fat diet(containing 1% cholesterol, 10% of egg yolk, 89% of the normal diet) 12 weeks. They were fed with high fat-diet loading(containing 2% cholesterol, 20% of cooked chicken egg yolk,78% of the normal diet) respectively, during the initial stage and 4th,8th,12 thweek of the high-fat diet. At the same time, collect blood samples through ear vein in fasting state and at the 2ed,4th, 6th, 8th hour after loading meal. Then, centrifugation the supernatant by centrifuging all blood samples was transferred to EP tubes, which were placed and stored in liquid nitrogen freezer of minus 70℃. To measure the plasma concentration of ox-LDL and PON1, after finishing all the blood samples to be collected. Detect the abdominal artery of rabbits by applying 6-15 MHz high-frequency ultrasound probe, during the initial stage and4 th,8th,12 thweek of the high-fat diet,and observe the smooth of the blood vessel wall,increasing in thickness of layer, atherosclerotic plaques attaching and the changes of the diameter of lumen. At the end of experiment of 12 weeks, all the animals were sacrificed.separated from the ascending aorta to the abdominal aorta artery. Observe the pathological changes of arteries under a microscope, after fixed, drawn, after producer, HE staining.Results:1. Changes of plasma ox-LDL in fasting and postprandial states of high-fat loading, in the process of ASDuring the process of AS, plasma level of ox-LDL in fasting state increases gradually, in8 th week increasing significantly(P <0.05). We can see that the oxidative modification of LDL showing a gradual worsening trend in AS progression associated with the increase in the oxidation reaction. After the high-fat loading, plasma ox- LDL levels increased firstly and then decreased. At the beginning of the first and 8thw of fat diet, plasma ox- LDL level increased significantly at the 2ed h of loading(P < 0.05). At the end of 4th w increased significantly at 2ed h(P <0.05). At the end of 12 th w compared with fasting, there is no difference(P > 0.05). We can consider that high-fat loading can cause oxidation reaction becoming strong.2. Changes of plasma PON1 in fasting and postprandial states of high-fat loading, in the process of ASDuring the process of AS, plasma PON1 activity tends to increase in fasting state,particularly in 12 th week increasing significantly(P <0.05). At the beginning of the fat diet,after the high-fat loading, plasma PON1 levels firstly increased and then decreased,increasing significantly at the 4th h(P <0.05). At the end of 4th and 12 th w, plasma PON1 levels firstly decreased and then increased. Plasma PON1 level is lowest at the 4ed h(P <0.05). We can think that serum PON1 activity level is associated with the progress of AS and high-fat loading can make antioxidant activity weaken.3. Ultrasound technology observe abdominal arteries of rabbitsAt first stage of high-fat diet, endothelial of abdominal artery is smooth. At 4th w of high-fat diet,arterial intimae become thick. At 8th w of high-fat diet, endothelial surface is rough. At 12 th w of high-fat diet, IMT of abdominal thicken significantly, and there are visible plaque on the surface of wall.4. Changes of ox-LDL in different time point correlated with AS(1) After 4 weeks of high fat diet, the levels of ox-LDL are correlated with the degree of atherosclerosis negatively, in fasting and postprandial state at each time point, especially after eating 8 hours correlated strongly(P <0.05).(2)After 8 weeks of high fat diet, the degree of atherosclerosis increased when the levels of ox-LDL decreased, in fasting and postprandial states at each time point, which is not considered significantly(P>0.05).(3)After 12 weeks of high fat diet, the degree of atherosclerosis increased when the levels of ox-LDL decreased in after loading 8 hours, but in other time points correlated negatively,which is not considered significantly(P>0.05).5. Changes of PON1 in different time point correlated with AS(1)After 4 weeks of high fat diet, the levels of PON1 and the degree of atherosclerosis were correlated positively, in fasting and postprandial state at each time point, which is not considered significantly(P>0.05).(2)After 8 weeks of high fat diet, the levels of PON1 and the degree of atherosclerosis were correlated negatively, in fasting and postprandial state at each time point, which is not considered significantly(P>0.05).(3)After 12 weeks of high fat diet, the levels of PON1 and the degree of atherosclerosis were correlated negatively in fasting state and after eating 6 hours, but in other time points correlated positively, which is not considered significantly(P>0.05).6. Visual observation of abdominal arteriesAfter high-fat diet for 12 weeks, there are obvious plaques in abdominal arteries.7. Pathology of the abdominal arteryAt the beginning of test, abdominal artery is smooth and continuous, there being no foam cells. After 12 weeks of high-fat diet,there are ridge caps in abdominal aorta wall,convening to lumen and foam cells, some of which swell particularly like vacuolization.Conclusion:1. In the gradual progression of atherosclerosis, ox – LDL and PON1 level increased in the fasting state, which may because enhancing the ability of organism between oxidation and anti-oxidation and keeping dynamic balance in gradually increasing level.2. In the early time of atherosclerosis,the level of ox – LDL is the highest after loading 2h, and in 12 weeks, 4 h is the highest. In the progress of arteriosclerosis, the level of PON1 is reduced after loading, in the 4weeks, the level of PON1 is the lowest after loading 8 h, after loading 4 h is the lowest in 12 weeks.Which prompt, antioxidant capacity in after loading 8 h is the weakest in the middle of the hardening of the arteries, and after loading 4 h antioxidant ability is to a minimum in the late of hardening of the arteries.