| Objective:Chemerin is a fat cell factor lately founded in adipose tissue, which is expressed in white adipose tissue, promote adipose cell differentiation and glucose transportation. Chemerin is a chemotactic factor, having effect on the inflammatory reaction cells (such as macrophages) by the paracrine way. It plays an important role in the metabolism of lipid and fat cells. It is also the key protein which can lead to obesity and type 2 diabetes. So far, whether chemerin can really enhance the inflammatory reaction of fat cells, liver tissue and other organs is not clear. This research is mainly using in situ hybridization method observe the different chemerin expression and related factors in the liver of rats, which include insulin resistance rats and IL-6 intervention diabetic rats; explore the effect of inflammation and lipid metabolism in obesity, insulin resistance and the development of incident diabetes.Methods:48 healthy SD male rats from two subgroups were randomly divided into six groups,8 rats in each group. Every rat's body weight is 247±4.9g. Diet-induced insulin resistant subgroup was divided into three groups:normal control group (NOR group) 8, normal saline; saturated fatty acid group (SFA group) 8, Intralipid gavage; trans-fatty acid group (TFA group) 8, margarine gavage. IL-6 intervention subgroup was also divided into three groups:diabetes mellitus IL-6 antigen group (group A); diabetes mellitus IL-6 antibody group (group B); diabetes mellitus control group (group C). All the rats weigh weekly, and taken the amount of press 1ml/100mg orally. The rats were fed with normal diet. At the 7th weekend, we tested fasting blood glucose and serum insulin in each group, the insulin levels were calculated and compared, it showed that the serum insulin level of intralipid gavage experimental group (SFA, TFA, A, B and C group) is higher than the NOR group. Weight the A, B, C group's rats on next early morning, intravenously inject 30mg/kg STZ to make mode. Measure the blood glucose three days later, which higher than 16.7mmol/L was set as a successful criterion for type 2 diabetes mellitus rat model. 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/day, intervenes continuously for 5 days; group B was continuously given intraperitoneal injection with 0.01 M the PBS fluid of 0.6ml/day for 4 days, on the 5th day, intraperitoneal injection of IL-6 antibody fluid (Img/ml) 0.6ml/day; group NOR, SFA, TFA and C were given intraperitoneal injection with 0.01M the PBS fluid of 0.6ml/day, intervenes continuously for 5 days. Until the 8th week, the animals were killed, drawing off blood from femoral vein, measuring fasting plasma glucose (FPG), fasting insulin (FINS), free fatty acids (FFA), high sensitive CRP (hs-CRP) and lipids. Enzyme linked immunosorbent assay (ELISA) was used to determinate the insulin receptor in rat liver tissue; the expression of chemerin on the liver of the rats were tested by in situ hybridization. All the data were analyzed by the SPSS 16.0 software.Results:Intralipid gavage 7 weeks, SFA, TFA, A, B, C fed rats'body weight increased significantly than the initial (all P<0.01). Compared with the control group, experimental group of five serum insulin increased significantly, the difference was statistically significant (P<0.05), ISI was significantly lower, HOMA-IR was significantly increased, the difference was statistically significant (P<0.05). All the type 2 diabetic rats were induced successfully by STZ. Compared with the initiation, the rats'body weight of SFA,TFA groups increased at the end of the experiment after 8 weeks, while the A, B and C group ones were higher than NOR group (P<0.05). Serum FINS levels of SFA, TFA, A, B, C groups were higher than the NOR group (P <0.01). FPG determination of A, B, C group was higher than NOR, SFA, TFA group (all P<0.01), A, B group and C group was not statistically significant. Hs-CRP determination in the SFA, TFA, A, B, C groups were higher than the NOR group (P<0.05). FFA determination of SFA, TFA, A, B, C groups were higher than NOR group (P<0.05). In SFA, TFA groups, TG, TC, LDL levels significantly higher than NOR group, the difference was significantly (P<0.01). The TG, TC and LDL levels of A, B, and C groups were higher than NOR group, the difference was significantly (P<0.05). Compared with NOR group, the HDL levels of experimental group were lower, the difference was statistically significant (P＜0.05). And chemerin was positively correlated with HOME-IR (r=0.544, P＜0.05), ISI (r=-0.544, P＜0.05), hs-CRP (r=0.575, P<0.05) and TG (r=0.7, P＜0.05), negatively correlate with LDL-C (r=0.77, P＜0.01).Conclusions:(1) Fat milk and margarine can successfully build insulin resistance mode, and the method is reliable. (2) Fat emulsion irrigation seven weeks in small doses with a tail intravenous STZ can successfully induce SD rats for type 2 diabetes. The method is reliable too. (3) The insulin resistance and the increase of type 2 diabetes rat's insulin receptor on the liver cell membranes may be associated with the decline of insulin sensitiity and functions. (4) Many factors have effect on chemerin expression, such as glucose, insulin, lipid metabolism and inflammatory reaction. And we find that chemerin expression level is high in insulin resistance period, though its expression level declines in type 2 diabetes periods, but still higher than normal level. Chemerin can somewhat reflect the insulin resistance level early. It can also aggravate the disfunction of fat cells and affect the liver tissue, but the mechanism of its interaction with other factors needs further research. We should try to establish reasonable eating habits, cut down the intake of high trans-fats and high saturated fats. We should also pay attention to reduce the incidence of diabetes and obesity, strengthen early prevention, early treatment and early diagnosis of diabetes, relieving the burden of patients and society. |
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