| Objective:To observe the effect of pioglitazone on expression of protein tyrosine phosphatase1B(PTP-1B),insulin receptor substrate2(IRS-2) in liver of rat with insulin resistance by high-fat-diet.Methods:Forty male SD rats were randomly divided into control group on regular diet (NC group, n=10), high fat diet group (HFN group, n=15) and high fat diet group administrated Pioglitazone(HFP group, n=15), the last two group(HF group) are on high fat diet. After twelve weeks, body weight, fasting blood glucose, fasting insulin, triglyceride, total cholesterol, insulin sensitivity were determined, and the histomorphological change in liver were observed; the fatty experimental group are treated with Pioglitazone (3mg/kg-d, intragastric administration), treatment was administered daily for2weeks. The control group and fatty control group all received an equal volume of vehicle (saline). The expression of PTP-1B and IRS-2in liver and skeletal muscle tissue was determined with immunohistochemistry, western-blotting and immunoprecipitation.Results:(1) In obesity rats induced by high fat diet, the body weight was significantly increased, the ISI was significantly decreased, and glucose and the acute first-phase insulin secretary response were impaired, fatty degeneration of liver was observed.(2) The PTP-1B expression and activity in HFN group were significantly increased compared with NC group, that in HFP group were significantly decreased compared with HFN group.(3) The IRS-2phosphorylation of HFN group was significantly lower than NC group, that HFP group was significantly increased compared with HFN group.Conclusion The obese bats after high fat diet appearance insulin resistance, and the PTP-1B level was increased, the IRS-2phosphorylation was decreased in liver tissue. Improved insulin resistance of pioglitazone may be relation with the low expression of PTP-1B and the high expression of IRS-2, which is insulin signal transduction molecule. |
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