| Insulin resistance refers to insulin functions lower than that in normal condition after insulin binding with insulin receptor, manifest as increasing hepatic glucose output and decreasing the rate of glucose uptake primary into striated muscle and adipose tissue. Owing to insulin action dependent on insulin signaling protein, insulin signaling pathway is defective when structure and function of signaling protein is dysfunctional, which forms insulin resistance. Factors affecting insulin resistance in vitro are simple, and it is easy to study the developmental mechanism of insulin resistance. Since the cell sources, inducers and methods had some differences in models in vitro or models in vitro and in vivo, usually the results were various, not good for studying the developmental mechanism of insulin resistance. Considering insulin resistance is a chronic, slowly developmental process with the existence of insulin in vivo, 3T3-L1 adipocytes wore treated with dexamethasone and insulin, induced to form insulin resistance, then glucose in medium was measured with clinical assay in minima] way and the molecular mechanism of insulin resistance was studied. At last, we regarded rosiglitazone often used in clinical cases as positive insulin sensitizer, screened out Chinese herbal, medicineto get new insulin sensitizer, and laid a foundation for developing new insulin sensitizers and application in clinical case in future. in order to search an reliable glucose-detecting method ,which similar to clinical glucose assay, to estimate the glucose variety of cells with insulin resistance in vitro, we detected glucose with GOD-POD assay used in clinical cases in minimal way, and found OD was directly proportional to glucose content, also could represent the content of glucose, so GOD-POD assay in minimal way was feasible, then taking advantage of characteristics of insulin-stimulated glucose uptake of cells to verify feasibility of method, we used GOD-POD assay in minimal way to detect glucose uptake of cells and found the characteristics of insulin was obvious, GOD-POD assay in minimal way was successful.After establishment of GOD-POD assay in minima] way, imitating the developmental condition of insulin resistance in vivo, 3T3-L1 adipocytes were treated with dexamethasone and insulin, then the glucose in medium was detected with GOD-POD assay in minimal way. The results showed that the ability of cells uptaking glucose was decreased, glucose remained in medium was increased, insulin resistance of cells formd.When cells with insulin resistance were treated with rosiglitazone, the ability of glucose- uptaking was raised, but still lower than that of normal cells.Considering the fact of insulin resistance is defective of insulin signal pathway, reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot technique were used to study the variety of insulin signaling protein and gene associated withinsulin resistance syndrome. The results were as following:1. After cells treated by dexamethasone and insulin together, the levels of Glut4 mRNA and protein were decreased obviously, the number of glucose transporter became smaller. When cells with insulin resistance were treated with rosiglitazone,both Glut4 mRNA and Glut4 protein of cells were increasd ,the ability of glucose-uptaking was raised, the insulin resistance of cells was improved.2. Insulin receptor substrate IRS-1 mRNA and protein wore Lessened evidently when cells were in insulin resistance; after the improvement of rosiglitazone, the levels of the mRNA and protein were unchangeable.3. Peroxisome proliferators activated receptor gamma (PPAR) was a very important nuclear receptor, which was closed with transcription of insulin signaling protein, when cells were in insulin resistance, their PPAR mRNA and protein were down-regulated clearly, but after resistance of cells was improved by rosiglitazone, PPAR mRNA and protein were up-regulated, but still lower than those in normal cells.4. c-Cbl associated protein (CAP) is on t...
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