The Role Of IL-6 In Type 2 Diabetes Mellitus Rats

Objective:In recent years,Prevalence of type 2 diabetes mellitus is increasing gradually,but its mechanism was not yet completely clarified,many researches have suggested that chronic low-grade inflammation plays an important role in the pathogenesis and development of type 2 diabetes mellitus.This study was designed to establish type 2 diabetes mellitus rat model and observe the influence of Interleukin-6(IL-6) antigen and IL-6 antibody on them,and analyze the different effects of the two interventions,the important role of IL-6 and other inflammation factors in the pathogenesis of diabetes are discussed.Methods:36 healthy SD male rats,divided into four groups randomly:Group N(normal control group,10);Group A(diabetes mellitus IL-6.antigen group,10);Group B(diabetes mellitus IL-6 antibody group,8);Group C(diabetes mellitus control group,8).All of them were fed with the regular diet.The rats of Group A,B and C were given intragastric administration with fat milk 1ml/100mg weight/day for 7 weeks,the similar dosage of water was given to N Group rats.At the 7th weekend, the level of plasma insulin was detected,the results showed that the level of plasma insulin in the fat milk intragastric administration groups(A,B,C group)were higher than normal control group.On the next morning,the weight of the rats were measured, according to 30mg/kg body weight,the vena caudalis of the rats were injected with STZ 3 days later,we tested the blood glucose of rats,if the result of the blood glucose was higher than 16.7mmol/L,it was succeed to establishing the type 2 diabetes mellitus rat model.After that,the rats were continuously given the regular diet and intragastric administration with fat milk(0.5ml/100mg weight/day) 2 days after establishing the type 2 diabetes mellitus rat model,Group A was given intraperitoneal injection with IL-6 antigen diluent(10ug/ml) of 0.6ml/one/day,intervenes continuously for 5 days;Group B was continuously given intraperitoneal injection with 0.01M the PBS fluid of 0.6ml/one/day for 4 days,on the 5th day,intraperitoneal injection of IL-6 antibody fluid(1mg/ml) 0.6ml/one;Group C and N were given intraperitoneal injection with 0.01M the PBS fluid of 0.6ml/one/day,intervenes continuously for 5 days;After establishing the type 2 diabetes mellitus rat model,all the rats were killed at 7th day.The serum insulin,lipidIL-6,free fatty acid were tested;The rat liver thin slice were used to test the insulin receptor,the expression of TL-6mRNA on the liver of the rats were tested by RT-PCR.All the data were analyzed by using the SPSS 11.5 software.Results:After 7 weeks of the diets enriched with fat and sugar,contrast to control group,the serum insulin of diabetes mellitus group A,B,C were significant higher (P＜0.05),the ISI of diabetes mellitus group A,B,C were lower(P＜0.05),the HOMA-IR of diabetes mellitus group A,B,C were significant higher(P＜0.05);Type 2 diabetes mellitus model in group A,B,C induced by STZ were all succeed.At the end of experiment,the weight of rats in diabetes mellitus group A,B,C were significant lower than control group(P＜0.05 );The serum TG,TC,LDL,FFA of group A,B,C were significant higher than group N(P＜0.05);Contrast to group N,the insulin receptor level on rats liver cell membrane of group A,,B,C elevated have statistics significance(P＜0.05);Contrast to Group B,C,N,the level of serum IL-6 in Group A rats were elevated significantly(P＜0.05);The expression of IL-6mRNA level in the liver tissues of Group A was significant higher than Group B,the difference between them has statistics significance(P＜0.05).Around the corresponding IL-6 antigen or antibody intervention,compared in the ABCN four groups of each group,the result demonstrated that the blood glucose in Group A,B,C were descent significantly(P＜0.05),but the fasting glucose did not show significant difference around the intervention(P＞0.05);Both Group B and Group C, after intervention,the level of insulin and HOMA-IR descent have statistics significance(P＜0.05),ISI was elevated Significantly(P＜0.05),but before and after intervention,only the change of insulin and HOMA-IR in Group B have the relevance (P＜0.05),the change of ISI did not have the relevance in Group A,B,C and N (P＞0.05).Conclusions:(1) Using intragastric administration with fat milk (high-glucose-high-fat diet) plus low dose STZ by vena caudalis,the type 2 diabetes mellitus SD rat model can be induced successfully,the method is reliable,and all the STZ injected SD rats feed with fat milk developed diabetes;(2)Because of the number of insulin receptor on type 2 diabetes mellitus rats liver cell membrane is increased,possibly related to the decrease of the insulin sensitivity and effect;(3) Exogenous IL-6 antigen could increase IL-6 level in serum and the liver of type 2 diabetes mellitus rat,through the increasing expression of inflammation cell factor influence diabetes.The level of insulin was not reduced,the insulin resistant degress wae not reduced,and the increasing of insulin sensitivity was not obviously;But the glucose was not elevated after IL-6 antigen intervention;(4) Exogenous IL-6 antibody could decrease insulin level and ease insulin resistant in type 2 diabetes mellitus rat;Its mechanism possibly relate to alleviate of the chronic low-grade inflammation.;But the level of blood glucose did not decrease after IL-6 antibody intervention.Whether IL-6 is a kind of pathogenic factors or protection factors,or just an inflammatory marker,we need to make it clearly in the future research.Then we will know the role of inflammatory cytokine in diabetes and the pathogenesis of insulin resistance,and the influnence to insulin sensitivity.