| Objective:To observe the function and its mechanism of PPARa when exercise intervenes the formation of fatty liver in ratwhich is high fat rich diet fed, to study the effect of exercise at different times that makes on the formation of fatty liver, to put forward theoretical bases for proving that exercise prevents the formation of fatty liver.Method:36Male SD rats are randomly grouped as control group (C group)、high fat rich diet feeding group (H group), high fat feeding+60min exercise group (HE+60min group)，C group and H group consisting of8rats, HE+60min and HE+90min consisting of10rats. Exercise Scheme:The60min exercise group should do12weeks exercise without weight loading,6days a week. They should be weighed weekly during study period. After12weeks, the contents of TG、TC、HDL、LDL、ALT、AST、FINS、FFA of serum and the contents of FFA、 NF-κB、TNF-α、PPARa should be examined separately, meanwhile. Morphological changes of liver tissue should also be observed under the light microscope.Results1, The influence that exercise put on body weight, liver wet weight and liver index of each group’s rats. After12-week swimming, body weight, liver wet weight and liver index of rats in fat rich diet feeding groups are much higher than those of in normal groups,The high-fat diet can cause the body weight,liver wet weight.liver index increased.Body weight, liver wet weight and liver index of rats in60-min group and90min group are all lower than those of in fat rich diet feeding group,Description of the exercise can reduce high-fat diet-induced body weight,liver wet weight and liver index increased.However, there is no difference in these indexes between60min group and90min group,Description60min and90min of exercise on body weight,liver wet weight and liver index has little effect.2、The influence that the exercisemakes on ALT.AST in rats’ blood lipid and serum is as follows: after12weeks swimming exercise, the contents of TG, TC. LDL in serum of rats in high fat diet fed groupare all obviously higher than those of in C group(P<0.01),High-fat diet in rats can cause lipid and serum ALT and of AST increased.which indicates that there is fatty buildup in rats after high rich diet feeding. The contents of TG,TC,LDL in serums of60min group and90min group are all lower than those of in high fat rich diet feeding group, which indicates that the exercise could decrease the contents of ALT.AST in blood lipid and serum of rats in H group. There is no difference in the contents of TG.TC.LDL between60min group and90min group, there is no difference in the content of HDL of rats in all groups.3.The influence that exercise makes on the contents of TG.TC.FFA in liver is as follows:after12-week swimming exercise, the contents of TG.TC in livers of rats in H group are much higher than those of rats in C group(P<0.01), which indicates that TG.TC in livers occurs after high fat rich diet feeding;the contents of TG.TC in livers of rats in60min group and90min are much lower than those of rats in H group(P<0.01),which indicates that exercise could decrease the contents of TG.TC in liver; The result that there is no difference in the contents of TG.TC in liver between60min group and90min group indicates that, exercise time makes no obvious difference in contents of TG.TC in liver, the contents of FFA in livers of rats in H group are much higher than those of rats in C group(P<0.01), which indicates that FFA in livers occurs after high fat rich diet feeding; the contents of FFA in livers of rats in60min group and90min are much lower than those of rats in H group(P<0.01),which indicates that exercise could decrease the contents of FFA in liver; The content of FFA in liver tissue of90min group is very much lower than that of in60min group, which indicates that a long term exercise could decrease the content of FFA in liver.4.The influence that exercise makes on the form of liver in rats of different groups is as follows: after12-week swimming exercise, normal liver is bright red coloring and its envelop is smooth and soft; The livers of rats in H group are swelling and yellow coloring, and their edgesare full. The color of rats in H+60min group is fawn and lusterless; the color of livers in rats of H+90min group is the same with normal one’sand the texture is tough. Morphological observation under light microscope find that, there is no steatosishappened to hepatic cells in rats of C group, the structure of hepatic lobules is normal, cell nucleus is located in the center of cell and cytoplasm is abundant; Comparatively, hepatic lobule in the ratof H group is hard to recognize, there is middle to high levelsteatosis happened to liver cells, the cells are very swelling and their cytoplasm are loose; For H+60min group, there is middle to high levelsteatosis happened to liver cells and different-sized lipid droplets could be seen in cytoplasm; For H+90min group, the structure of hepatic lobule and hepatic sinusoid iscomparatively clear, micro lipid droplets could been seen occasionally.5. The influence that the exercise makes on blood sugar and HOMA-IR is as follows:after 12-week swimming exercise, there is no difference in the blood sugar of rats in difference group. Compared with C group, the content of HOMA-IR in H group increases obviously(P<0.01), which indicates that insulin resistance occurs after high fat rich diet feeding; the contents of HOMA-IR in60min group and90min group are much lower than those of in H group(P<0.01), which indicates that a long term exercise could decrease the content of HOMA-IR of rats in H group. There is no difference in the contents of HOMA-IR between60min and90min, which indicates that exercise time makes no obvious difference in the contentof HOMA-IR.6. The influence that exercise makes on the contents of NF-κB、TNF-α、PPARa in livers of rats are as follows:after12-week swimming exercise, the contents of NF-κB in liver tissue of rats in H group are much higher than those of rats in C group(P<0.01), which indicates that high fat rich diet feeding method could increase the content of NF-κB; Through comparison of H group and H+60min group and H+90min group, it could be found that exercise could decrease the content of NF-κB which wasincreased by high fat rich diet feeding. The content of TNF-a in livers of rats in H group are much higher than those of rats in C group(P<0.01), which indicates that high fat rich diet feeding could increase the content of TNF-a in liver. Through comparison of H group and H+60min group and H+90min group, it could also be found that exercise could decrease the content of TNF-a which were increased by high fat rich diet feeding.The content of TNF-a in liver of H+90min group is lower than that of in liver of H+60min group, however, there is no statistical significance, which indicates that exercise time makes no obvious effect on the content of TNF-a.Besides, the content of PPARa in livers of rats in C group is higher than that of rats in H group (P<0.05), which indicates that high fat rich diet feeding could decrease the content of PPARa; Thecontent of PPARa in livers of rats in H group ismuch lower than that of rats in H+60min group and H+90min group (P<0.01), which indicates that exercise could increase the content of PPARa in livers of H group; The content of PPARa in livers of H+90min group is higher than that of rats in H+60min group, however, there is no statistical significance. which indicates that exercise time makes no obvious effect on the content of PPARa in liver.4Conclusion1. After12-week fat rich diet feeding, these rats get significant increase in weight, liver index and liver wet weight, and also in TC.TG content of serum and liver. Through pathological observation, there is badly fatty infiltration in hepatic tissue, while the ALT.AST activity of serum improves greatly, the content of FFA in serum and liver increase greatly, which means that12-week fat rich diet feeding experiment duplicates the model of fatty liver in rats.2. A long-term moderate exercise could rise the contents of PRARa in liver of fat rich diet fed-rat, could adjust energy metabolism and lipid oxidation and maintain dynamic balance of lipid metabolism within the body so that it can prevent the formation of fatty liver.3. PRARa plays an important role in the study of taking exercise as a method to prevent fatty liver when rats are high fat rich diet fed which causes the formation of fatty liver, the possible mechanism is as follows:Long-term regular swimming can promete the transport and metabolism of FFA in the liver.which can inhibition of NF-κB and reduce the activity of NF-κB,lead to liver generated TNF-a reduced that TNF-a reduced insulin can restrain the signal transdution pathway,so as to improve insulin sensitivity,rise PPARa the intimacy compeptency scale expression.PPARa the intimacy competency scale up exepression,can make the oxidation of fatty acid increases,the inhibition of lipid accumulation in the liver and thus play a role in the formation interfere with fatty liver. |
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