The injection of streptozotocin(stz) at a high dose (60 mg/kg) into young male rats produces direct beta cell destruction and leads to insulin dependent diabetes (IDD). In contrast the injection of multiple smal doses of stz (40 mg/Kg/d for 5 days) produce IDD, which resembles type l diabetes in man. The provocative effects of the pertussis vaccine (PV) and cyclosporin(CA) against the development of IDD induced by stz were studied. When PV in a dose of 3.75 X 10(10) microorganism was administered to single or multiple stz treated rats, hyperglycemia still developed and persisted during the experiment. No difference was noted in blood glucose levels, but plasma insulin levels were higher in PV treated rats. When CA (10 mg/kg) was administered daily to single or multiple stz treated rats, hyperglycemia seemed to be lower, but this was not statistically significant, however, plasma insulin levels were higher in CA treated rats. The results of this experiment suggest that PV and CA provide some protection to the beta cells of the pancreas.
Animal ; Blood Glucose/metabolism ; Cyclosporins/pharmacology* ; Diabetes Mellitus, Experimental/prevention & control* ; Diabetes Mellitus, Insulin-Dependent/chemically induced ; Male ; Pertussis Vaccine/pharmacology* ; Rats ; Rats, Inbred Strains

Animals ; Diabetes Mellitus, Experimental/drug therapy* ; Fibrosis/prevention & control* ; Hyperglycemia/prevention & control* ; Hypoglycemic Agents/pharmacology* ; Inflammation/prevention & control* ; Male ; Rats ; Rats, Sprague-Dawley ; Stilbenes/pharmacology*

OBJECTIVE: To investigate the effects of subcutaneous administration of insulin on insulitis,beta cell apoptosis and diabetes in non-obese diabetic (NOD) mice, and to explore the mechanism of immune tolerance induced by insulin. METHODS: Sixty female NOD mice were randomly divided into insulin group (n=32) and phosphate buffered saline (PBS) group (PBS group, n=28). Insulin was subcutaneously injected with humulin N (60 microL, 6U)+IFA (60 microL) at 4, 12, 20, and 28 weeks respectively, while the PBS group received PBS (60 microL) + IFA (60 microL). Insulitis and beta cell apoptosis of islets were observed at 12 weeks. IL-4 and IFN-gamma in the sera were measured by enzyme linked immunosorbent assay (ELISA). The expression levels of I-Abeta(g7), IL-4, IFN-gamma, IL-1beta, and Fas mRNA of islets were measured by reverse transcription-polymerase chain reaction (RT-PCR) at 12 weeks. RESULTS: The incidences in the insulin group were significantly lower than those in the PBS group (21.4% vs 71.4% at 30 weeks, 28.6% vs 85.7% at 52 weeks, P<0.05). The insulitis scores in the insulin group were lower than those in the PBS group, but there was no statistical significance. Fas expression on islets and apoptotic beta cell rates in the insulin group were lower than those in the PBS group (P<0.05). In the insulin group, serum IL-4 levels were higher, but IFN-gamma levels were lower than those in the PBS group (P<0.05). The levels of I-Abeta g7, IFN-gamma, IL-1beta and Fas mRNA transcription in islets were lower in insulin group, but IL-4 mRNA levels were higher than those in the PBS group (P<0.05). CONCLUSION The specific autoantigen insulin may induce immune tolerance and prevent diabetes in NOD mice, but it can't block the progression of insulitis. Subcutaneous administration of insulin can induce the regulatory T cells, and make Th1 to Th2 cytokine shifts in system and islets, thus preventing the Fas-mediated beta-cell apoptosis and diabetes.
Animals ; Apoptosis ; drug effects ; Diabetes Mellitus, Experimental ; prevention & control ; Diabetes Mellitus, Type 1 ; prevention & control ; Female ; Injections, Subcutaneous ; Insulin ; administration & dosage ; pharmacology ; Islets of Langerhans ; immunology ; pathology ; Mice ; Mice, Inbred NOD ; Pancreatitis ; prevention & control ; Random Allocation

OBJECTIVETo explore the effect of Zhenqing Recipe (ZQR) on renal structure and expressions of matrix metalloproteinase-9 (MMP-9), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in experimental type 2 diabetic rats.

METHODSThe rat models of type 2 diabetic were set up by intraperitoneally giving small-dose streptozotocin (STZ) after fed with high carbohydrate and high fat diets for one month. The model rats were randomly divided into the model group,the high and low dose ZQR-treated groups,and the enalapril-treated group; a normal control group was also established. The course of treatment continued 8 weeks. The expressions of MMP-9, TIMP-1, and fibronectin (FN) in renal tissues were detected by immunohistochemistry. The morphological changes of glomeruli and renal tubules were checked by microscopy.

RESULTSCompared with the normal control group, the expression of TIMP-1 and FN increased and MMP-9 decreased in the model group; the treated groups could decrease the expressions of TIMP-1 and FN, and increase the expression of MMP-9, especially the high-dose ZQR group had the best effect. The morphological changes of renal tubules and glomerulus in the treated groups were improved better as compared with the model group.

CONCLUSIONThe protective effect of ZQR on renal structure may be achieved by modulating the expressions of MMP-1 and TIMP-1.

Animals ; Diabetes Mellitus, Experimental ; enzymology ; metabolism ; prevention & control ; Diabetes Mellitus, Type 2 ; enzymology ; metabolism ; prevention & control ; Drugs, Chinese Herbal ; pharmacology ; Fibronectins ; metabolism ; Kidney ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Protective Agents ; pharmacology ; Rats ; Tissue Inhibitor of Metalloproteinase-1 ; metabolism

OBJECTIVETo investigate the influence of total flavonoids of epimedium (TFE) on the streptozocin (STZ)-induced kidney injury in diabetic rats and discuss the possible mechanism.

METHODSDiabetes was produced by a single injection of streptozocin (40 mg/kg, iv) in male SD rats. The rats were randomly divided into three groups (n = 10): control group, model group and TFE group (100 mg/kg, ig). Animals were sacrificed 12 weeks later. The level of blood glucose, blood urea nitrogen (BUN) and creatinine (Cr) as well as the renal index were determined. Detect the specific biochemical of renal tissue: superoxide dismutase (SOD), malondialdehyde (MDA). Use masson staining to observe the morphology of the renal tissue. Immunohistochemistry was employed to determine the protein levels of transforming growth factor-beta1 (TGF-beta1).

RESULTSCompared to control group, the enhancement of blood glucose, renal index, BUN and Cr was found in model group, which was significantly attenuated by treatment with TFE. Meanwhile, elevated MDA level in renal tissue as well as decreased SOD activities in renal tissue were significantly remitted by TFE. Furthermore, TFE decreased the expression of TGF-beta1.

CONCLUSIONTFE can evidently relieve renal damage in rats with diabetic nephropathy induced by STZ, which might be related to antioxidation and modulating the expression of TGF-beta1 protein.

Animals ; Diabetes Mellitus, Experimental ; metabolism ; Diabetic Nephropathies ; metabolism ; prevention & control ; Epimedium ; chemistry ; Flavonoids ; pharmacology ; Kidney ; drug effects ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effects of luteolin (Chinese Traditional Medicine) on cardiac functions and mitochondrial oxidative stress in streptozotocin (STZ)-induced diabetic rats.

METHODSMale SD rats were randomly divided into a normal control group, a luteolin control group, a diabetic group, and diabetic groups orally administered with a low dose (10 mg/(kg x d)) or a high dose of luteolin (100 mg/ (kg x d)) for eight weeks. The body weight, blood glucose, cardiac functions, left ventricular weight, myocardial collagen and reactive oxygen species (ROS) levels were assayed. The cardiac mitochondrial ROS level, superoxide dismutase (SOD) activity and the mitochondrial swelling were measured.

RESULTSTreatment with luteolin had no effect on the blood glucose but reduced the losing of body weight in diabetic rats. High dose of luteolin markedly reduced the ratio of ventricular weight and body weight, increased the left ventricular develop pressure, and decreased the left ventricular end diastolic pressure in diabetic rats. The myocardial levels of ROS and collagen, the cardiac mitochondrial ROS level, and the mitochondrial swelling in diabetic rats were all markedly reduced by high dose of luteolin. Furthermore, high dose of luteolin significantly increased the mitochondrial SOD activity in diabetic rat hearts.

CONCLUSIONTreatment with luteolin for 8 weeks markedly improves the cardiac function, which may be related to reducing mitochondrial oxidative stress and mitochondrial swelling in diabetic rats.

Animals ; Diabetes Mellitus, Experimental ; metabolism ; physiopathology ; Luteolin ; pharmacology ; Male ; Mitochondria, Heart ; metabolism ; Oxidative Stress ; physiology ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species ; metabolism ; Ventricular Dysfunction ; prevention & control

OBJECTIVETo investigate the effects and related mechanisms of ghrelin on myocardial neovascularization in diabetic rats with experimental myocardial infarction (MI).

METHODSAdult male SD rats were divided into six groups (n = 20 each group): control, diabetes mellitus (DM), MI, DM+MI, DM+MI+ghrelin, DM+MI+ghrelin+D-Lys3-GHRP-6 (GHSR1a inhibitor). DM was induced by streptozotocin (STZ, 60 mg/kg), 3 months later, MI was induced by left anterior descending artery ligation in DM rats. DM+MI+ghrelin group received ghrelin 200 µg×kg(-1)×d(-1) and DM+MI+ghrelin+D-Lys3-GHRP-6 group received ghrelin 200 µg×kg(-1)×d(-1) and D-Lys3-GHRP-6 50 mg×kg(-1)×d(-1) for 4 weeks. Then, cardiac function was measured by echocardiography, microvascular density (MVD) was measured by CD34 immunohistochemistry, myocardial infarct size was determined by Masson staining, the mRNA and protein expressions of vascular endothelial growth factor (VEGF) and receptors Flk-1, Flt-1 were detected by real-time PCR and Western-blot, respectively.

RESULTSCompared with MI group, MVD (15.3 ± 1.0 vs.20.7 ± 1.6, P < 0.05), left ventricular ejection fraction (LVEF) ((64.2 ± 3.4)% vs. (81.3 ± 3.8)%, P < 0.01), left ventricular fractional shortening (LVFS) ((31.7 ± 1.1)% vs. (48.8 ± 3.3)%, P < 0.01) and the mRNA and protein expression of VEGF, Flk-1 and Flt-1 (P < 0.01) were reduced, while myocardial infarct size ((55.8 ± 3.1)% vs. (35.7 ± 2.5)%, P < 0.01) was increased in DM+MI group. These effects were partly reversed in DM+MI+ghrelin group and the beneficial effects of ghrelin were partly abolished by D-Lys3-GHRP-6 (all P < 0.05).

CONCLUSIONSOur results demonstrate that ghrelin could improve microvascular density, cardiac function, and reduce myocardial infarct size of diabetic rats with myocardial infarction via modulating GHSR1a-mediated expressions of VEGF, Flk-1 and Flt-1.

Animals ; Blotting, Western ; Coronary Vessels ; Diabetes Mellitus, Experimental ; Echocardiography ; Ghrelin ; physiology ; Male ; Myocardial Infarction ; prevention & control ; Myocardium ; Neovascularization, Physiologic ; Oligopeptides ; Rats ; Vascular Endothelial Growth Factor A ; Ventricular Function, Left

OBJECTIVEAs an endogenous antioxidant, taurine could retard the development of diabetic cardiovascular complications. Whereas, whether TAU has a protective effect on diabetic vascular endothelium in young patients is still unclear. This study aimed to investigate the protective effect of taurine on early vascular endothelial dysfunction and its possible mechanism by detecting the changes of oxLDL/LOX-1 system in young STZ-induced diabetic rats. Doing so, the authors expect to find an effective approach in clinical practice to the prevention and treatment of diabetic vascular complication.

METHODSix-week-old rats were divided randomly into normal control (CN group, n=8), diabetes mellitus group (DM group, n=8) and taurine supplement group (DM+TAU group, n=8). Diabetes was induced in the rats by intraperitoneal injection of streptozotocin (STZ, 60 mg/kg) and after the onset of diabetes, the rats in DM+TAU group were given free access to drinking water containing 1% taurine. At the end of 4 weeks, blood glucose, serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL), oxidized low density lipoprotein (oxLDL) and sICAM-1 levels were determined, meanwhile LOX-1 and ICAM-1 expression on abdominal aortas were examined by immunostaining, Western blotting and reverse transcription PCR, respectively. The results were quantified by densitometry.

RESULTCompared to normal control, in STZ-induced diabetic rats, the levels of serum TC, TG, LDL, oxLDL and sICAM-1 were all increased (P<0.01 for all), meanwhile LOX-1 and ICAM-1 expression (protein and mRNA) in the endothelium layers of abdominal aortas were also markedly enhanced (P<0.01 for all); while in taurine supplemented rats, the levels of serum TG (0.64+/-0.12 vs. 0.97+/-0.18), TC (0.82+/-0.18 vs. 1.01+/-0.23), oxLDL (3.1+/-0.6 vs. 4.2+/-0.6), sICAM-1 (108.3+/-18.0 vs. 130.7+/-17.4), expression of LOX-1 and ICAM-1 protein (1.02+/-0.19 vs. 2.60+/-0.33, 1.21+/-0.22 vs. 2.98+/-0.31) as well as mRNA (0.45+/-0.09 vs. 0.96+/-0.15, 0.50+/-0.07 vs. 0.87+/-0.16) were all markedly lower than those of untreated diabetic rats (P<0.05 for all). Also, the level of LOX-1 protein expression was positively correlated with levels of serum oxLDL (r=0.922, P=0.001), sICAM-1 (r=0.753, P=0.031) and ICAM-1 expression on abdominal aorta (r=0.849, P=0.008).

CONCLUSIONVascular endothelial dysfunction was present in early stage of young diabetic rats and taurine supplement could protect against this early endothelial dysfunction by its antioxidation to inhibit the role of oxLDL/LOX-1 system in young rats with diabetes mellitus.

Animals ; Diabetes Mellitus, Experimental ; drug therapy ; metabolism ; Diabetic Angiopathies ; prevention & control ; Endothelium, Vascular ; metabolism ; Male ; Oxidative Stress ; Rats ; Rats, Wistar ; Taurine ; therapeutic use

AIMTo investigate the effects of ramipril on myocardial ischemia/reperfusion injury in diabetic rats, and to explore its mechanism according to the observation on myocardial ultrastructure.

METHODSStreptozotocin induced diabetic rats were divided randomly into three groups (n = 16): ischemia/reperfusion (I/R), ischemic preconditioning (IPC) and ramipril (RAM) group. Rats in RAM group were administered by RAM(1 mg x kg(-1) x d(-1)) orally for 4 weeks, the others were administered by normal saline. Then all rats were subjected to myocardial ischemia/ reperfusion injury. Rats in IPC group were preconditioned before ischemia. The ECG and the infarct size were examined. The changes of myocardial morphology were examined by light and electron microscopes.

RESULTSCompared with I/R group, the elevation of ST segment and the incidence of ventricular tachycardia and ventricular fibrillation during ischemia were significantly decreased, the infarct size at the end of reperfusion was remarkably reduced, the myocardial morphology were significantly improved, special structure of myofilaments and mitochondria remained clearly, blood vessels were unobstructed, injury of endothelium were decreased in PC and RAM groups.

CONCLUSIONRamipril administered for 4 weeks induces myocardial protection in diabetic rats, which is similar to that of IPC. The mechanism may be involved in protection of cardiocytes and mitochondria, and improvement of endothelial function.

Animals ; Cardiotonic Agents ; pharmacology ; Diabetes Mellitus, Experimental ; complications ; Ischemic Preconditioning, Myocardial ; methods ; Myocardial Reperfusion Injury ; pathology ; prevention & control ; Myocardium ; ultrastructure ; Ramipril ; pharmacology ; Rats

OBJECTIVETo explore the impact of diabetic condition on the protective effect of diazoxide preconditioning (DPC) on ischemic-reperfused (I/R) myocardium in rats.

METHODSThirty normal male Sprague-Dawley rats were divided into 3 groups, including non-diabetic control group, non-diabetic I/R group, and non-diabetic I/R DPC group. Thirty diabetic male rats were also divided into the same 3 groups. The Langendorff isolated heart perfusion models were established. The control groups had a 90 min perfusion without any intervention. The I/R groups had a 30 min equilibration period, a 30 min ischemia, and a 30 min reperfusion. The I/R DPC groups had a 10 min equilibration, two cycles of 100 micromol/L diazoxide perfusion, 5 min each, followed by a 5 min diazoxide-free period before the 30 min ischemia and a 30 min reperfusion. The recovery rate of the left ventricular function, including cardiac output, left ventricular developed pressure (LVDP), and the maximum change rate of left ventricular pressure rise and fall (+/- dp/dt(max)) were recorded. The activity of creatine kinase in coronary outflow and activities of malonyldialdehyde, and superoxide dismutase in myocardium were detected. Myocardial water content was also assessed.

RESULTSIn non-diabetic rats, the content of creatine kinase, malonyldialdehyde and water content were significantly decreased in I/R DPC group compared with those in I/R group. Furthermore, in I/R DPC group, the activity of superoxide dismutase and the recovery rate of the left ventricular function, including cardiac output, LVDP and +/- dp/dt(max), were significantly increased compared with those in I/R group (P < 0.05). By contrast, there were no significant changes between I/R DPC group and I/R group in diabetic rats (P > 0.05).

CONCLUSIONDiabetes counteracts the protective effect of the diazoxide preconditioning on ischemic reperfused rat heart, which may be related with acute insulin resistance in cardiomyocytes.

Animals ; Diabetes Mellitus, Experimental ; Diazoxide ; pharmacology ; In Vitro Techniques ; Ischemic Preconditioning, Myocardial ; Male ; Myocardial Reperfusion Injury ; metabolism ; physiopathology ; prevention & control ; Myocardium ; metabolism ; Rats ; Rats, Sprague-Dawley ; Ventricular Function, Left