Dosage of streptozocin in inducing rat model of type 2 diabetes mellitus

Objective To investigate the dosage of streptozocin (STZ) in inducing rat model of type 2 diabetes mellitus. Methods Male Wistar rats were fed with high-fat diet for 8 weeks, then different dosage of STZ (20 mg/kg, 25 mg/kg, 30 mg/kg) was injected intraperitoneally. Observed the body weight, fasting glucose and 2 h postload glucose for 7 weeks. Insulin (INS), triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL) levels were tested at the end of the experiment. Serial pancreatic sections were made and stained with hematoxylin-eosin (HE) and immunohistochemistry. Results The 20 mg/kg of STZ injection group had low successful rate (30%). The 25 mg/kg of STZ injection group had the highest making model success rate of 73.3%, and stable moderate hyperglycemia. Islet structural integrity, but the beta-cell number and cytoplasmic brown granules decreased. The 30 mg/kg of STZ injection group had highest mortality and higher blood glucose, the number of islets decreased obviously, small islets more common, islet structure is not complete. Conclusion High-fat high-sugar feeding for 8 weeks combined with low-dose STZ (25 mg/kg) can result in rat model more representative of human type 2 diabetes mellitus.