Objective To determine the effect of thiazolidinediones (TZDs) on early retinopathy in rats with experimental diabetes. Methods In 40 rats, diabetic models were set up in 36 by one-off intraperitoneal injection with streptozotocin (STZ), and other 4 were in the normal control group. Twenty-four diabetic rats with the disease-duration of more than 6 months underwent intravitreous injection (with rosiglitazone or pioglitazone in 10 rats, respectively), and the rest 4 rats werenprime;t injected with drugs as the diabetic positive control group. Immunohistochemical treptomycin-avidin-biotin-complex (SABC) method, in situ hybridization of retinal vascular endothelial growth factor (VEGF) mRNA, and TdT-dUTP terminal nick-end labelling (TUNEL) were performed on the ocular paraffin section to detect the cellular apoptosis. The difference of VEGF expression and cellular apoptosis between TZDs and control group was observed and analyzed. Results The results of immunohistochemical staining and hybridization in situ were negative in the normal control group. The positive expression rate of VEGF was lower in rosiglitazone and pioglitazone group than which in the diabetic positive control group, and there was no obvious differences of positive expression of VEGF mRNA and cellular apoptosis between the 2 groups. Conclusion TZDs (rosiglitazone and pioglitazone) may inhibit the positive expression of VEGF protein in retina of STZ-induced diabetic rats to some extent, but not affect the growth of VEGF in retina. (Chin J Ocul Fundus Dis, 2006, 22: 7-10)
ObjectiveTo observe the adhension and stracking of leukocyte in the capillary vessels, and investigate the relationship between leukocyte and microvascular morphologic changes in retinal microvesselsof rats with early diabetes.MethodsA total of 90 healthy adult male Wistar rats were randomly divided into control and diabetes (induced by Streptozotocin, STZ) groups with 45 rats in each group. The rats in the diabetic group were further divided into 3, 7, and 14 days groups with 5 rats in each group, and 30, 90, and 180 days groups with 10 rats in each group. The right eyes of rats in each group were prepared for retinal digest preparations. The expression of leukocyte common antigen (CD45) was detected by immunohistochemical staining.ResultsFew CD45 positive cells in the retinal capillaries were seen in the control group. The expression of CD45 was significantly increased in the retinal capillaries 3 days after diabetes induction, and reached a peak at the 14th day. Morphological changes including capillary telangiectasia, atresia, and irregularity of capillary caliber were found in the retinal capillaries of rats 90 days after diabetes induction. The changes were aggravated 180 days after diabetes induction.ConclusionLeukocyte adhesion occurs in the early stage of diabetic retinopathy (DR), and is the beginning of the microvascular pathological changes. Leukocyte adhesion may play an important role in the occurrence and development of DR as the foundation of microvascular morphological changes.(Chin J Ocul Fundus Dis, 2003,19:344-347)
ObjectiveTo establish a model of fetal hyperglycemia and explore the effects of hyperglycemia on alveolar cell apoptosis,proliferation and the development of lung structure in neonatal rats. MethodsForty SD pregnant rats were randomly divided into a hyperglycemia group (STZ group) and a normal pregnancy group (N group)(n=20 in each group). The rats in STZ group and N group were intraperitoneally injected streptozotocin(STZ,40 mg/kg) or the same bulk of citrate buffer respectively at the 4.5 days after gestation. Blood glucose concentration of the pregnant rats was measured before injection,at the 6.5,11.5,16.5 and 20.5 days after gestation,respectively. The weight,survival rate,lung weight,septal thickness,radical alveolar count,alveolar cell apoptosis and proliferation of neonatal rats were recorded after birth immediately (D0) and at 7 days (D7). ResultsCompared with N group,the blood glucose level increased after intraperitoneal injection of STZ in STZ group (P<0.05). The Survival rate of STZ group was lower than that of N group at D0 and D7 (P=0.00). The neonatal weight,lung weight,septal thickness of STZ group were lower compared with those of N group at D0(P<0.05). However,there was no significant difference between two groups in radical alveolar count. The alveolar apoptosis index of STZ group was higher than that of N group at D0 [(11.8±1.1)% vs. (3.4±0.7)%,P=0.00]. Alveolar cell proliferation significantly increased in STZ group compared with N group at D0 and D7 (P<0.05). ConclusionsThe fetal hyperglycemia model is successfully established by intraperitoneal injection of STZ 40 mg/kg. Fetal hyperglycemia can increase mortality,alveolar cell proliferation and apoptosis,and affect the development of lung structure of neonatal rats.
ObjectiveTo evaluate the influencing factors and explore a better method of making rat model of type 2 diabetes by high fat and sugar diet and streptozotocin(STZ) injection. MethodsSixty SPF grade of 6 weeks male SD rats were fed with high fat and glucose diet by 4 weeks and then randomly divided into 3 groups, the control group rats(n=20) were injected citric acid by 50 mg/kg and fed with normal diet, and the diabetes mellitus group rats were further divided into 2 subgroups by the different doses of STZ:the rats of diabetes mellitus model group 1(n=20) were injected by 50 mg/kg, while the rats of diabetes mellitus model group 2(n=20) were injected by 35 mg/kg. The diabetes mellitus model group rats were fed with high fat and glucose diet continually. The fasting blood glucose(FBG) were measured on day 3, 7, 10, and 14, respectively. The success model rate(blood glucose > 16.7 mmol/L after 14 days) and the mortality rate were calculated. Meanwhile fasting serum insulin level(FSI), total serum cholesterol(TC), and triglyceride(TG) were measured. ResultsCompared with the control group, the levels of FBG, FSI, TC, and TG were increased significantly in the diabetes mellitus model group 1 and 2(P < 0.05). And insulin sensitivity was worsen markedly(P < 0.05). But the diabetes mellitus model group 2 had higher success rate of making model(85% vs. 75%) and lower mortality(0 vs. 25%), P < 0.05. ConclusionRat model of type 2 diabetes induced by 4 weeks of high fat and sugar feeding and 35 mg/kg STZ injection has high morbidity, strongly security, and stable features.