The Effects Of Intermittent Hypoxia On The Formation Of Nonalcoholic Fatty Liver Disease In Mice

Objective: To study and observe the influence of intermittent hypoxia on the formation of nonalcoholic fatty liver disease in mice and its mechanism, for exploring new ways and means of clinical prevention and treatment of nonalcoholic fatty liver disease.Method: 1. The model of non-alcoholic fatty liver disease was established by feeding with high fat and sugar in mice; The role of the low oxygen(15%)environmental stimuli and its work time were determined by the AMPK activity in liver cells; Lesion degree was determined by conventional pathological methods and the effects of intermittent hypoxia and metformin on the pathological process of nonalcoholic fatty liver disease in mice. 2.The experimental groups and steps:(1) Establish the model of non-alcoholic fatty liver disease in mice: A closed group of 30 Kunming(Km) male mice were randomly divided into normal control group and high fat and sugar model group. And then, the changes of weight were measured and the degrees of liver fat were observed until the model of non-alcoholic fatty liver disease was established.(2) Screen the working time of 15% low oxygen environmental stimulus: 25 Km male mice were randomly divided into 5 groups: groups treated with low oxygen for1 h, 2 h and 4 h, and normal control group and group treated with metformin.They were given ordinary feed. At the end of the experiment, the mice were anesthetized and executed, and then the livers were collected. The AMPKa activity was detected by Western blotting to screen the working time of 15% low oxygen environmental stimulus.(3)The effects of intermittent hypoxia on the pathological process of nonalcoholic fatty liver disease in mice: 48 Km male mice were randomly divided into 4 groups: group A blank control group, group B high fat and sugar model group, group C low oxygen intervention group, and group D Metformin group. The changes of the weight were weighed and recorded once a week. Group A was feed with ordinary diet, group B、C and D were feed with high fat and sugar diet. Beginning from the fifth week, Group C was exposed to 15% oxygen environment for 1 h once a day, group D was given Metformin by intraperitoneal injection once a day(100mg/kg/d). At the end of the eighth week, the mice were anesthetized and executed.And then the livers and blood were collected, and the blood glucose,liver function and pathological changes were detected by biochemical methods and liver HE staining slice,respectively.Results: 1. A model of non-alcoholic fatty liver was replicated successfully in mice feeding with high fat and sugar。 2. According to the result from the experimental model, intermittent hypoxia at the concentration of 15% oxygen for 1 h was the best. 3. The influence of intermittent hypoxia on the process of nonalcoholic fatty liver disease in mice, the results were as follows:(1) The results from the routine pathological observations: There was no fatty change in gruop A, mild-to-moderate fatty change in group C and D, and severe fatty change in group B. Compared with group B, the fatty change had significant difference in group C and D(P<0.05),but there was no significant difference between group C and D. These data showed that the pathological process of nonalcoholic fatty liver disease was effectively slowed by intermittent hypoxia.(2) The results from the detection of hepatic functions: The serum ALT was the lowest in group A, the highest in group B, and the moderate in group C and D. Compared with group B, there were significant difference in group A, C and D(P<0.05),but there was no significant difference between group C and D. The serum AST in group B was higher than the other. Compared with group B,there were significant difference in group A, C and D(P<0.05),but there was no significant difference between group A,C and D. These results showed the hepatic functions were significantly reduced because of the liver damage induced by the high fat and sugar diet.(3) The changes of average body weight: the body weight in group A was increased at the natural rate, the slowest in group B, and the body weight in group C and D were increased between group A and B. Compared with C and D, there were significant differences in group A and B(P<0.05),but there was no significant difference between group C and D.(4) The results of blood sugar and lipid: the level of the fasting blood sugar(FBS)in group A was the highest, the lowest in group B, and the level of FBS in group C and D were between group A and B. Compared with group A, there were significant difference in group B, C and D(P<0.05),but there was no significant difference between group C and D. The serum TG in group B,C and D were higher than that in group A. Compared with group A, there were significant difference in group B, C and D(P<0.05), but there was no significant difference between group B,C and D. The serum TC in group B was higher than that in group A,but lower than that in group C and D. Compared with group A, there were significant difference in group B, C and D(P<0.05), but there was no significant difference between group C and D.Conclusion: 1. The model of non-alcoholic fatty liver could be successfully replicated by feeding with high fat and sugar in mice, and the fatty liver model was reversible. 2. The pathological process of nonalcoholic fatty liver disease was effectively slowed by intermittent hypoxia, reducing the damage of liver function, improving the weight gain and decreasing the FBS level,but no obvious effect on hyperlipidemia. 3. Similar to metformin, the mechanism of anti-fatty liver induced by intermittent hypoxia might activate the activity of AMPKa. Thus, we thought that the intermittent hypoxia might have potential prospect in clinical application.