Effects Of Nanometer Propolis On Metabolic Disorder And Insulin Resistance In T2DM Rats

Objective: To investigate the effects of nanometer propolis on glycometabolism, lipid metabolism, protein metabolism, oxidative stress, Hepatic function, renal function and insulin resistance in type 2 diabetes mellitus (T2DM) rats.Methods: 1. Rat model of type 2 diabetes: Male Sprague-Dawley rats were fed with high-energy diet and then injected with low dose streptozotocin (STZ) for 4 times, to make the rats hyperglycaemia and insulin resistance. 2. Grouping & handling: After the T2DM models were prepared successcully, based on body weight and fasting blood glucose, 72 T2DM rats were randomly divided into 6 groups, each group administrated with corresponding drugs: low-dose nanometer propolis group (50 mg nanometer propolis/kg.d), middle-dose nanometer propolis group (100 mg nanometer propolis/kg.d), high-dose nanometer propolis group (200 mg nanometer propolis/kg.d), ordinary propolis group (30 mg ordinary propolis/kg.d), positive drug group (10 mg Pioglitazone Hydrochloride/kg.d), model control group (2%PEG400 1 ml/100g.d). Get another 12 normal male SD rats as normal control group (2%PEG400 1 ml/100g.d). 3. Test index: To observe the level of body weight (BW), fasting blood glucose (FBG), fructosamine (FMN), glycosylated hemoglobin(HbAlc), fasting insulin (FINS), total cholesterol (TC), triglycerides (TG), high denscity lipo cholesterol (HDL-C), low denscity lipo cholesterol (LDL-C), superoxide dismutase (SOD), malonaldehyde (MDA), blood urea nitrogen (BUN), creatinine (CREA), total protein (TP), albumin (ALB), alanine aminotransferase (ALT), aspartate aminotransferase (AST) in each group. Measure the level of glucose infusion rate (GIR) and blood glucose (BG) at steady state in Glucose clamp experiment.Results: 1. Body weight: All rats were growing steadily during experimental session.The BW of rats administed with nanometer propolis and ordinary propolis had no significant difference with model rats. The BW of rats administrated with positive drug were higer than model rats, had significant differences at 7th and 10th week after administration. 2. Glycometabolism: In experimental session, the FBG of model control group were significantly higer than normal control group (PO.05), the FBG of nanometer propolis and positive drug treated rats were notably lower than model control group synchronization (PO.05). The FMN of model control group were significantly higer than normal control group 6 weeks after administration (PO.05, PO.01), the rats administrated with positive drug had lower level of FMN than model control group (P<0.05), however the level of FMN in rats administrated with nanometer propolis and ordinary propolis had no significant difference with model control group (P>0.05). The content of HbA_lc in model control group were signicicantly higher than normal control group (P<0.01), The content of HbA_lc in middle and low dosage of nanometer propolis group, positive drug group were significantly lower than model control group (P<0.05, P<0.01), there were no significant difference of HbAlc between high-dose nanometer propolis group, ordinary propolis group and model control group (P>0.05). FINS were higer and IAI were lower in model control group than those in normal control group (P<0.05), FINS in low-dose nanometer propolis group and positive drug group were significantly lower than model control group (P<0.05), IAI of rats which treated with nanometer propolis, ordinary propolis and positive drug were significantly higer than model control group (P<0.05). 3. Lipid metabolism: 4 weeks after administration, the level of TG in model control group were significantly higer than normal control group (P<0.05), treated with nanometer propolis, ordinary propolis and positive drug can depress the level of TG in T2DM rats (P<0.01, P<0.05). In experimental session, there had no significant difference of TC, HDL-C level between model control group and normal control group, and no significant difference of TC, HDL-C level between nanometer propolis groups and model control group (P>0.05). LDL-C level in model control group were significantly higer than normal control group at 6th and 10th week after administration (P<0.05), there had no significant difference of LDL-C levelbetween nanometer propolis groups, ordinary propolis group, positive drug group with model control group (P>0.05). 4. Antioxidation: The activity of SOD in model control group were depressed significantly than normal control group (PO.05), treated with nanometer propolis and positive drug can improve the activity of SOD (P<0.05). The content of MDA in model control group were rised significantly than normal control group (PO.05), treated with nanometer propolis, ordinary propolis and positive drug can significantly decrease the MDA content (PO.05, P<0.0\). 5. Protein metabolism, renal function and hepatic function: The content of TP, ALB in model control group were decreased significantly compared with normal control group (PO.05), treated with low dose nanometer propolis can significantly increase the TP level (PO.05). The level of BUN, CREA, ALT and AST in model control group were no higer than those in normal control group (P>0.05). Treated with nanometer propolis, ordinary propolis and positive drug had no side effect on renal and Hepatic function, the level of BUN, CREA, ALT and AST had no significant difference compared with model control group (jP>0.05). 6. Insulin resistance: At the condition of l.Oml/h insulin rate and 4.8mmol/l steady blood glucose, administrated with middle and low dose of nanometer propolis and ordinary propolis can significantly increase the GIR (PO.01) compared with model control group, indicate that nanometer propolis and ordinary propolis can enhance the insulin sensitive ofT2DMrats.Conclusion:1. Fed with high-energy diet and then injected with low dose streptozotocin (STZ) can provide an animal model which simulates human type 2 diabetes mellitus.2. Nanometer propolis can decrease the level of FBG and HbA|C in T2DM rats, it can also increase IAI and GIR, enhance the insulin sensitive in T2DM rats.3. Nanometer propolis can depress the TG leve in T2DM rats and can regulate the lipid metabolism in T2DM body.4. Nanometer propolis can improve the activity of serum SOD and decrease the content of serum MDA, can resist oxidative damage in T2DM body.5. Nanometer propolis can protect renal, liver and pancreas in T2DM rats.