Abstract

BACKGROUND
Korean diabetes is different from western diabetes due to the racial differences in genetic factors and susceptability. It has recently been suggested that thrifty phenotype hypothesis is related to the recent increase in prevalence of Korean diabetes, but we have little evidence about that. We obtained basic materials in the animal model of type 2 diabetes mellitus and conducted a morphologic study of the beta cell change, insulin secreting capacity, and glucose metabolism. METHODS: To obtain the reference data of a non-insulin dependent diabetic animal model, we performed the intraperitoneal glucose tolerance test (IPGTT), hyperinsulinemic euglycemic clamp and immunobistochemical staining on the sacrificed pancreatic tissues on a Sprague-Dawley male rat into which streptozotocin (STZ) had been injected during the early neonatal period. The study groups consisted of a normal control group with citrate buffer injection, a group with injection of 50 ug STZ per kg of weight and a group with injection of 75 ug STZ per kg of weight. STZ was injected within 12 hours after birth. RESULTS: l. Although, STZ injected groups had lower body weight than the control group 7 weeks after birth, there were no differences during 14 weeks. 2. The IPGTT results showed that the average level of whole blood glucose concentration of the group with 50 ug STZ per kg of weight was higher than that of the control group at 7 and 14 weeks after birth. The mean serum insulin concentration of the 75 ug STZ per kg of weight injected group was lower than that of the control group at 7 weeks after birth, but it was higher than that of the control group at 14 weeks. 3. The hyperinsulinemic euglycemic clamp study showed that the average level of peripheral glucose disposal rate of the STZ injected groups was lower than the control group, but there were no differences in the study groups. 4. Pancreatic islet showed decreased beta cell mass and increased beta cell size in the STZ injected groups but the BrdU labelling index was not different between the control and study groups. CONCLUSION: STZ injection into neonatal Sprague-Dawley male rats may result in a diabetic status due to both decreased insulin secretion and increased insulin resistance, which gives us useful reference data for type 2 diabetes mellitus in the animal model.

• Keywords: Key Words;Diabetes;Streptozotocin;Insulin secretion;Insulin resistance;