An Experimental Study On Levels Of Serum Interleukin-6, Insulin And E₂ In Obese Rats

IntroductionObesity is a disease that energy intake is more than energy consumption , then it results in more adipose deposition in vivo. Epidemiology indicates.- obesity has become a very serous healthy problem. Therefore, it has an important meaning to investigate the pathogeny of obesity and to prevent the occurring and developing of obesity.It is difficult to study obesity in humans because of many reasons. Models have been maken a use of to acquire information which would not otherwise be obtainable. Perhaps the most relevant of these models with regard to human obesity are those in which obesity develops in response to increase dietary fat. Levin et al found that the part of the rats fed the same high fat diet was obese and part was not obese in 1983. The former group is referred to as obesity prone (OP) , whereas the latter group is referred to as obesity resistant( OR).High - fat diet is a significant contributor to hyperphagia, weight gain, and fat deposition. The higher fat content has been associated with metabolic and hormonal changes that promote fat storage. Thefield of cytokines has expanded tremendously over the last 2 decades . Initially, they were thought to be products of the immune system alone that had immune and hematologyical functions only. Yet, it has become increasingly apparent that cytokines participate in a neuroend-crine and immune system network, in which both the nervous and endocrine systems participate. Interleukin -6, in particular, has drawn much attention in the endocrine field for it is the most " endocrine" of all cytokines. In human obesity and animal obese models, expression of the cytokine in adipose tissue and its levels in serum are higher than in lean controls. IL - 6 appears to play a critical role in obesity - related insulin resistance. Now there is no report in our country about how the IL - 6 levels change and what causes the change and the relation in IL - 6, obesity and insulin. The text utilizes the above animal models to examine the levels of serum IL - 6, insulin and E2 ( estradi-ol) in order to find the action of IL - 6 in obesity and hormone of its metabolism and provide theoretical basis for the study of obesity.ObjectiveThe purposes of this experiment are;1. Investigating the levels of IL - 6 in obesity - prone and obesity resistant rats.2. Assessing early and late serum levels of insulin and E2 induced by high - fat diet in obesity - prone and obesity resistant rats.3. Investing if IL - 6 is associated with obesity - related insulin resistance.Materials and MethodsAnimals and Diets. Thirty - five female Wistar rats weighting 170 10g were obtained from the animal Department of China Medical University. Animals were individually housed in cages in a temperature -controlled room(22 5 ) with a 12 - hour light/dark cycle. Animals were given free access to diets and water over the duration of the stud-y. For induction of obesity, 28rats were given a high - diet and 7rats were given a standard diet as control. The composition of diets is listed on Table 1.Experimental procedures. Both groups of rats were initially fed a standard diet for 1 week before the high - fat or control diets were started. All rats were maintained on their allotted diet for 10 weeks. At the end of every week in the entire study period, body weights were measured. At each time point ( 1, 10weeks) rats were given fast for 24h before blood were sampled at the eye vein. All samples were centri-fuged after 2h, and the serum was stored at - 80 .Over the 10 - wk period, rats fed the high - fat diet diverged into two groups based on body weight gain. The rats with the greatest weight gain were referred to as obesity - prone, others were referred to as obesity - resistant.Assays. Serum IL -6, insulin and E2 concentrations were determined by radioimmunoassay. TC,TG and blood sugar concentrations were determined by biochemical method. Statistical method. Data were analyzed across multiple groups by one - way ANOVA. All values are expressed as means...