Intervention Effects Of Aerobic Exercise And Soy Polypeptide On The Informing Of High-fat-diet-induced Fatty Liver Disease And Its Mechanisms

Objective:To explore the intervention effects of aerobic exercise and soy polypeptide on the informing of high-fat-diet-induced fatty liver disease , and discover the possible mechanisms.Methods:60 SD rats were divided randomly into five groups: Ordinary feed control group (C group), high fat diet group (HF group), high fat diet + exercise group (HE group), high fat diet + soy peptides group (HS group), high fat diet + exercise + soy peptides group (HSE group). The model of fatty liver in rats were induced by high fat diets. And the other group rats fed with high fat diet concurrent with exercise,or soy polypeptide,or exercise and soy polypeptide to prevent fatty liver disease. The training plan for tht rats was 60 minutes'unloaded swimming which would be done 6 days per week for 10 weeks.The dose of the SPI was 500mg/kgBW. The serum TG,TC contents,AST,ALT,LDH activities,and TG,TC,TNF-α,IL-6 and MDA contents and SOD activity in the liver were detected at the end of experiment while the morphological changes of the liver tissues were observed under light and transmission electron microscope.Results:(1)Compared with C group, the serum TG,TC contents increased significantly in HF group,and the levels of TG,TC and FFA in the liver increased significantly,too. Through the double factor variance analysis, both of aerobic exercise and the supplement of SPI could lower the serum TG and TC contents in rats fed high fat diet significantly. Although aerobic exercise could decrease the level of TG and TC in the liver of the HE rats, the diffirence is not significan(tp>0.05).However,aerobic exercise can lower the level of FFA in high fat diet rats significantly. But the supplement of SPI could dramatically lower TG,TG and FFA concentration of the liver in the high fat diet rats. Meanwhile,Aerobic exercise and the supplement of SPI displayed a obvious interaction on lowering TG and TC contents in serum and liver in high fat diet rats(p<0.01).(2)Compared with C group,the serum ALT in HF group had a trend of increasing,but not obvious(p>0.05),but the serum AST and LDH activities showed a dramatically increase. Through the double factor variance analysis, both of aerobic exercise and the supplement of SPI could lower the serum AST,ALT and LDH activities in HF rats significantly. And aerobic exercise and the supplement of SPI displayed a obvious interaction on lowering the serum AST and LDH activities,so that the serum AST and LDH activities could be reduced further more.(3)Compared with C group,IL-6 content in high fat diet rats'liver showed a obvious trend of increasing,but there was not significant difference(p>0.05),but the level of TNF-αshowed a dramatically increase(p<0.01). Through the double factor variance analysis, both of aerobic exercise and the supplement of SPI could lower the level of IL-6 and TNF-αin HF rats'liver significantly(p<0.01). Aerobic exercise and the supplement of SPI displayed a obvious interaction on lowering the IL-6 concentration in high fat diet rats'liver(p<0.01). Hower aerobic exercise and the supplement of SPI can reduce the level of TNF-αin livers,but not displayed an obvious interaction(p>0.05).(4)Compared with C group, the SOD activity in the livers of HF group desreased significantly(p<0.01),while the concentration of MDA increased dramaticlly(p<0.01),so the ratio of SOD/MDA descreased remarkably(p<0.01). Through the double factor variance analysis, both aerobic exercise and the supplement of SPI could increase the SOD activity in high fat diets rats'liver (p<0.01)and lower the concentration of MDA significantly(p<0.05), so the ratio of SOD/MDA increased significantly(p<0.01). Aerobic exercise combined soy polypeptide increased the SOD activity and decreased the MDA concentration in the liver of high fat rats further more,and showed a significant interaction.While aerobic exercise combined soy polypeptide can increase the ratio of SOD/MDA,but not appeared a significant difference.(5)In HF group,light microscope observation revealed swelling of hepatocytes and the liver displayed moderate and severe steatosis,different sizes of lipid droplets inside the cytoplasm. The hepatosinusoidal became narrow. The strcture of hepatocell in HE group were normal, and the nucleolus of the hepatocells were in the centre,but few microlipid vacuoles could be found occasionally. The strcture of hepatocell in HS group were nomal in principle,and the nucleolus of the hepatocell were in the centre, few microlipid vacuoles could be found. The hepatic cord tended to be normal and the hepatosinusoidal became norrow slightly. The hepatocell in HES group disposed round the central vein in actinomorphous,and the nucleolus were in the centre of the cell. Few microlipid vacuoles could be found in the cell occasionally. The structure of the hepatocable were normal and the hepatosinusoidal had no obviousely change.(6)Transmission electron microscope observation revealed,the ultrastructure of the hepatocytes in the control group were nomoral, but that in HF group displayed obvious pathological changes,and the ultrastructure in other groups seemed normally,few lipid vacuoles and dropsical mitochondria could be found occasionally.Conclusions:(1)10 week's high fat diet not only successfully induced the rats to form noalcoholic fatty liver disease,but also lead to the formation of NASH.(2)Concurrent with the formation of noalcoholic fatty liver disease induced by high fat diet,aerobic exercise and the supplement of soy polypeptide prevented high-fat-diet-induced fatty liver disease, and singal exercise training and the supplement of soy polypeptide displayed significant interaction in the formation of fatty liver disease to some indexes.(3)High-fat-diet-induced fatty liver disease appeared a relationship with lipid metabolism in blood and liver, and the cytokines played an important role in the occurrence and development of fatty liver,such as TNF-αand IL-6. Aerobic exercise and soy polypeptide prevented high-fat-diet-induced fatty liver disease by regulating the lipid metabolism in the blood and liver,decreasing hepatocytes and inflammatorycytes to release TNF-αand IL-6,and abating the damage of hepatocytes.( 4 ) The oxygen free radicals increased roughly concurrent with high-fat-diet-induced fatty liver disease,it might be the mechanism of hepatocells damaged and the serum enzyme activities increased. Aerobic exercise and the supplement of SPI could improve the metabolism of free radicals in high fat diet rats to prevent the damage of liver.