Experimental Study On Effect Of Interleukin-6 In Non-Alcoholic Fatty Liver Disease Rats

Objective: To establish a rat model of non-alcoholic fatty liver disease (NAFLD) with the high-lipid nutrition; To observe the change of rats'weight,liver index,hepatic enzyme,blood fat,insulin resistance,tumor necrosis factor-α,interleukin-6 and the pathological changes during the development of NAFLD; To analyze the relativity between the concentration of interleukin-6 and the degree of insulin resistance,tumor necrosis factor-αand steatosis; To discuss the possible mechanism of NAFLD.Methods: Forty-eight male SD rats were divided into normal group(n=24) and model group(n=24) randomly; Normal group were fed with normal diet whereas the model group were fed with high-lipid nutrition which was mixed with 84% normal diet adding 2% cholesterol and 14% lard. All rats were sacrificed at the end of 2, 4, 6, and 10 weeks and given a fasting for 12 hours, weighted up and the levels of serum triglyceride(TG),total cholestero(lTC),alanine aminotransferase(ALT),aspartate aminotransferase(AST),fasting blood glucose(FBG),fasting insulin(FINS),tumor necrosis factor-α(TNF-α) and interleukin-6(IL-6) were measured and insulin resistance index(IRI) was counted; The livers were dissociated carefully and weighted up, then liver index was counted and liver tissue serosity were made to measure the concentration of TNF-αand IL-6 in liver; The pathological changes was observed under light microscope.Results: The weights of rats in model group increased faster than normal group in total. The liver index was higher than normal group's from the end of week 4 (p<0.05). The levels of TG,TC,ALT,AST,FINS and TNF-αin serum of model group all increased at the end of week 4 while IL-6 increased at week 6(p<0.05). Compared with control group, the concentration of TNF-αin liver was higher at week 2 and IL-6 began to elevate from week 4(p<0.05), they are both increased significantly at week 10(P<0.01); The different pathological changes of liver in model group was recorded during experiments. The hepatocyte steatosis began from week 2, mild fatty liver was observed at the end of week 6 and developed to severe one at the week 10; The result of correction analyzing indicated that the levels of IL-6 in the serum and liver all positively related to FINS,IRI,TNF-αand the degree of hepatocyte steatosis.Conclusion: The rat model of non-alcoholic fatty liver disease was successfully established by feeding high-lipid nutrition for 6 weeks; IR plays an important role in the development of NAFLD; IL-6 was highly related to TNF-α,IR and hepatocyte steatosis, so it is an important adipokine and may participate in the pathogenesis of NAFLD. Measuring the concentration of IL-6 in serum may help to diagnose NAFLD and assess its severity.