A Study On The Levels Of Serum TNF-α, IL-6, CRP And The Association With Insulin Resistance In Obese Rats

IntroductionThe incidence of obesity has increased obviously with the development of e-conomy and the level of human living. Obesity, as a common dystrophic disease , has been thought of a crucial risk factor of hypertension, coronary heart disease, non - insulin dependent diabetes mellitus and so on. It influences health and living quality of human being severely. Therefore, it has an important theoretical and practical meaning to investigate the mechanism of obesity and to prevent the occurring and developing of obesity.Many studies have shown recently higher correlation between obesity and insulin resistance ( IR). Adipose tissue plays important role in mechanism of IR. TNF-a and IL-6 from Adipose tissue are hotspot. It is reported by Ford ES that higher TNF-a and IL-6 from Adipose tissue promote the level of CRP in obese individuals, and CRP is possibly associated with insulin resistance. The purpose of the following experiment is to investigate the changes of serum TNF-a, IL-6, CRP of dietary - obese rats, the relationship of the cytokines and the relationship to insulin resistance, and provide a new idea for prevention and cure of obesity.Objective1. Investigating levels of serum lipid,FPG changes in obese rats induced by high - fat diet.2. Investigating levels of serum TNF-a, IL-6, CRP changes in obese rats in-duced by high - fat diet.3. Investigating whether TNF-a,IL-6,CRP associated with obesity and obesity - related insulin resistance.Materials and MethodsAnimal and Diets;34 male Wistar rats weighting 170 卤 lOg were obtained from the Animal Department of China Medical University. The rats were in a temperature - controlled room (22 卤5掳C ). They were given free access to diets and water over the duration of the study.Experimental procedure:34 rats were initially fed on a standard diet for 1 week, 17 rats were given a high - fat diet to induce obesity, the other 17 rats were given a standard diet as control. The composition of diets is listed on Table. After 6weeks, 8 rats were killed after sampled blood from high - fat diet group and control group randomly. The others were maintained their allotted diet for 12weeks. At every weekend in this period, body weights were measured. At the end of experiment, all rats were killed after sampled blood. Abdominal fat pads (peri-renal, epididymal, mesenteric) were excised, weighted. All blood samples were centrifuged and the serums were stored at - 70^.Assays: Serum TNF-a and IL-6 and FINS concentrations were assayed with radioimmunoassay kits. Serum CRP concentration was assayed with velocity scatter nephelometer assay. Serum total cholesterol (TC) ,triglyceride (TG) , high density lipoprotein ( HDL) , low density lipoprotein ( HDL) , FPG levels were assayed with enzyme method.Stastistical method; All variables are expressed as means 卤 SD. Data was analyzed by Students t -test. Correlation was tested using Pearson'method. All analyses were carried out using SPSS statistical software.Results1. body weights Changes of high -fat group and control groupThere was no difference between the two groups before diet - induced obesi-ty ( P > 0. 05 ) . After 6 weeks , body weights of high - fat group were significantly greater than those in control group (P <0. 01). After 12 weeks, body weights of high - fat group were also significantly greater than those in control group ( P2. Rats Abdominal fat pads depot during experimentAt the end of 6 week , the weights of mesenteric , epididymal fat pads were heavier than those in control group ( P < 0. 05 ) , peri - renal (P<0.01); At the end of 12 week, all variables were significantly heavier than those in control group(P<0.01).3. Changes of serum lipid,FPG levels in high -fat group and control group After 6weeks , there was no difference in the serum TC , LDL , HDL levelsbetween the two groups ( P > 0. 05 ) ; The levels of serum TG, FPG were increased in high - fat group than those in control group ( P < 0. 05 ); After 12weeks , TG, LDL, FPG were significantly incr...