201012-1335嗯嗯呃(3)

嗯嗯呃

- 3 - 中国科技论文在线injection and was carried out for 15 days .

All the animals were randomly divided into the seven groups with 10 animals in each group. Group I served as normal controls and received vehicle only (distilled water). Group II served as normal treated with 0.4 mg/kg of trans-tiliroside. Group III served as diabetic control and received vehicle. Group IV, V and Ⅵ received the trans-tiliroside (0.4, 0.8 and 1.6 mg/kg b.w., respectively). Group Ⅶ was the standard drug metformin (125 mg/kg b.w.). The vehicle or test drugs were administered orally (suspended in distilled water).

1.5.2 Streptozotocin-induced diabetic rats

Diabetes was induced by a single intravenous injection of 60 mg/kg body weight of freshly prepared streptozotocin (STZ) dissolved in 0.1M citrate buffer, pH 4.5[10]. The control animals were treated with 0.1M citrate buffer (pH 4.5). Blood samples were obtained from the tail veins of the rats 7 days after STZ or vehicle injection. Glucose levels were measured with a portable glucometer, using reagent strips (One Touch ®Ultra ®, LifeScan). Only animals with fasting glucose over 11.1 mmol/L were considered diabetic and used for the present study.

The diabetic animals were again divided into six groups consisting of eight animals in each group. Group I served as normal controls and received vehicle only(distilled water). Group II served as normal treated with 1.2 mg/kg of trans-tiliroside. Group III served as diabetic control and received vehicle. Group IV and V received the trans-tiliroside (0.3 and 1.2 mg/kg b.w., respectively). Group Ⅵ was the standard drug metformin (93.75 mg/kg b.w.). The vehicle or test drugs were administered orally (suspended in distilled water). The dose of the trans-tiliroside (1.2 and 0.3 mg/kg) was fixed as optimum based on our alloxan-induced diabetic mice study (1.6 and 0.4 mg/kg). The treatment with tiliroside was started 7 days after STZ injection and was lasted for 12 weeks.

1.6 Analytical method

1.6.1 Assessment of trans-tiliroside on serum glucose levels

The blood samples of all mice were centrifuged (3000 rpm for 15min at 4℃) for separating the serum. After that, the serum was frozen at -80℃ for the following assessment for the fasting blood glucose (FBG). FBG determined before the start of the experiment. After 15 days of drug treatment, the FBG of mice were determined.

1.6.2 Estimation of lipids and lipoprotein level in serum

Twenty-four hours later after the last drug administration, the blood was collected from the eyes (venous pool) under aether anaesthesia, and then the animals (mice and rats) were sacrificed by cervical dislocation. The serum was stored at −80℃ after separation for the following biochemical analysis. The tissues were also stored at −80℃ until required. The fasting serum TC and TG were estimated in mice. The fasting serum TC , TG , LDL-C and HDL-C were determined using test kits in rats.

1.6.3 Measurement of SOD and MDA level in serum

The serum was used immediately for the assays of SOD activities and MDA level in rats following the commercial kits instructions.

1.7 Histopathological examination

The pancreas of mice was removed immediately from the animals after sacrificing and rinsed in ice-cold saline. The tissue samples were fixed with 10% formaldehyde, dehydrated in a graded