| Objective:To investigate effects of PGL on type 2 diabetic rats and research its action mechanism.Methods:The type 2 diabetic rat models were established by feeding with high-glucose-lipid diet and intraperitoneal injection of small-dose streptozotocin (STZ,35 mg kg-1).After the T2DM models were prepared successfully, the T2DM rats were randomly divided into 5 groups:diabetes model group (Model), low-dose PGL group (PGL-L,60 mg·kg-1), middle-dose PGL group (PGL-M,120 mg·kg-1), high-dose PGL group (PGL-H,240 mg·kg-1), positive drug Rosiglitazone group (RSG, 3mg·kg-1). Another 12 normal SD rats were added as normal control group (Control). Each group was administrated with corresponding drugs. In addition, the Model and Control group were administrated with N.S. in the same volume. All rats were administered daily for 6 weeks. During the experiment, while the body weight and blood glucose of rats were monitored once a week. The water and food consumption were observed daily. At the sixth weekend, the blood of all rats was drawn from abdominal aorta. The level of fasting blood glucose (FBG) was measured by GOD-POD. The level of fasting insulin (FNIS) was measured by radioimmunoassay. The level of blood lipid and glycated hemoglobin (GHb) was measured by enzyme coupling spectrophoto-metry. And the level of glycosylated serunm proteins (GSP) was measured by fructosamine assay. The concentration of alanine aminotransferase (ALT), aspartate aminotransferase (AST) were measured by Reitman assay. At the same time, the concentration of creatinine (Cr), blood urea nitrogen (BUN) were measured by deproteinization assay. Liver and kidney specimens were prepared for histopathological sections by HE staining. The protein expression of PPARy in the adipose tissue was observed by western blot.Results:1. The type 2 diabetes animal models have been established successfully. After high-glucose-lipid diet and small-dose streptozotocin injection, the rats' average concertration of 2 hours blood glucose reached to 17.4 mmol·L-1. And there are sympotoms of excessive appetite and thirst, urinating frequently, denuding and losing weight. At the same time, while the level of fasting blood glucose, glycated hemoglobin and serum fructosamine in the plasma of Type 2 diabetic rats increased, the serum insulin and insulin sensitivity index went down. And there was a sign of various degrees of damages in the liver and kidney (P≤0.01 or P≤0.05).2. PGL could decrease the level of blood glucose in the diabetic rat, which can be proved as follows:the levels of fasting blood glucose and glycated hemoglobin in rats treated with PGL drug were significantly lower than diabetic rats,and the level of serum insulin, insulin sensitivity index were increased(P≤0.01 or P≤0.05).3. PGL could decrease the level of blood lipid in the diabetic rat, which can be proved as follows:the levels of serum triglyceride, cholesterol and free fat acid in rats treated with PGL drug were lower than diabetic rats (P≤0.Olor P<0.05).4. PGL could improve the liver damage caused by diabetes obviously, which can be proved as follows:the levels of alanine aminotransferase and liver index in rats treated with PGL drug were lower than diabetic rats (P≤0.01 or P<0.05).5. PGL could improve the kidney damage caused by diabetes obviously, which can be proved as follows:the levels of creatinine, blood urea nitrogen and kidney index in rats treated with PGL drug were lower than diabetic rats(P≤0.01 or P≤0.05).6. The protein expressions of PPARγin the adipose tissue of rats treated with PGL drug were increased (p≤0.05).Conclusion:The PGL could be used to treat diabetes effectively. It could decrease the level of blood glucose, blood lipid of diabetic rat obviously, promote the level of serum insulin, and increase the insulin sensitivity index. In some extent, it could protect the function of liver and kidney. Its action mechanism was through activating PPARγprotein and increasing its protein expression.
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