PURPOSE: Alzheimer's disease (AD) results in memory impairment and neuronal cell death in the brain. Previous studies demonstrated that intracerebroventricular administration of streptozotocin (STZ) induces pathological and behavioral alterations similar to those observed in AD. Agmatine (Agm) has been shown to exert neuroprotective effects in central nervous system disorders. In this study, we investigated whether Agm treatment could attenuate apoptosis and improve cognitive decline in a STZ-induced Alzheimer rat model. MATERIALS AND METHODS: We studied the effect of Agm on AD pathology using a STZ-induced Alzheimer rat model. For each experiment, rats were given anesthesia (chloral hydrate 300 mg/kg, ip), followed by a single injection of STZ (1.5 mg/kg) bilaterally into each lateral ventricle (5 microL/ventricle). Rats were injected with Agm (100 mg/kg) daily up to two weeks from the surgery day. RESULTS: Agm suppressed the accumulation of amyloid beta and enhanced insulin signal transduction in STZ-induced Alzheimer rats [experimetal control (EC) group]. Upon evaluation of cognitive function by Morris water maze testing, significant improvement of learning and memory dysfunction in the STZ-Agm group was observed compared with the EC group. Western blot results revealed significant attenuation of the protein expressions of cleaved caspase-3 and Bax, as well as increases in the protein expressions of Bcl2, PI3K, Nrf2, and gamma-glutamyl cysteine synthetase, in the STZ-Agm group. CONCLUSION: Our results showed that Agm is involved in the activation of antioxidant signaling pathways and activation of insulin signal transduction. Accordingly, Agm may be a promising therapeutic agent for improving cognitive decline and attenuating apoptosis in AD.
Agmatine/*therapeutic use ; Alzheimer Disease/*chemically induced/*drug therapy ; Animals ; Cognition Disorders/*chemically induced/*drug therapy ; Disease Models, Animal ; Male ; Rats ; Streptozocin/*toxicity

OBJECTIVETo investigate the effects of diabetes mellitus on amplitude of distortion product otoacoustic emissions ( DPOAE) and whether streptozotocin has ototoxicity or not.

METHODSTwenty-four SD rats were divided into diabetes mellitus group, insulin therapy group and control group. Diabetes was induced by streptozotocin. The blood glucose of insulin group was controlled by insulin. The amplitude of DPOAE was tested before streptozotocin injection and 3 months, 5 months after injection, respectively.

RESULTSThe amplitude of DPOAE in diabetes rats was decreased in 3 months and there was statistical significance (P <0. 05) in 1038, 4126 and 5200 Hz, while obviously reduced in 5 months in all frequencies and there was also statistical significance (P <0. 01). The amplitude of DPOAE in all frequencies lacked of any significance between insulin therapy group and control group.

CONCLUSIONSDiabetes mellitus could induce the amplitude of DPOAE decreasing. Streptozotocin had not evident toxicity for inner ear.

Animals ; Blood Glucose ; analysis ; Diabetes Mellitus, Experimental ; physiopathology ; Ear, Inner ; drug effects ; physiopathology ; Hearing Tests ; Male ; Otoacoustic Emissions, Spontaneous ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; toxicity

BACKGROUNDPrenatal hyperglycaemia may increase metabolic syndrome susceptibility of the offspring. An underlying component of the development of these morbidities is hepatic gluconeogenic molecular dysfunction. We hypothesized that maternal hyperglycaemia will influence her offsprings hepatic peroxisome proliferator-activated receptor coactivator-1α (PGC-1α) expression, a key regulator of glucose production in hepatocytes.

METHODWe established maternal hyperglycaemia by streptozotocin injection to induce the maternal hyperglycaemic Wistar rat model. Offspring from the severe hyperglycemia group (SDO) and control group (CO) were monitored until 180 days after birth. Blood pressure, lipid metabolism indicators and insulin resistance (IR) were measured. Hepatic PGC-1α expression was analyzed by reverse transcription polymerase chain reaction and Western blotting. mRNA expression of two key enzymes in gluconeogenesis, glucose-6-phosphatase (G-6-Pase) and phosphoenolpyruvate carboxykinase (PEPCK), were analyzed and compared.

RESULTSIn the SDO group, PGC-1α expression at protein and mRNA levels were increased, so were expression of G-6-Pase and PEPCK (P < 0.05). The above effects were seen prior to the onset of IR.

CONCLUSIONThe hepatic gluconeogenic molecular dysfunction may contribute to the metabolic morbidities experienced by this population.

Animals ; Female ; Hyperglycemia ; chemically induced ; physiopathology ; Insulin Resistance ; physiology ; Liver ; metabolism ; Male ; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha ; Peroxisome Proliferator-Activated Receptors ; metabolism ; Pregnancy ; Prenatal Exposure Delayed Effects ; RNA-Binding Proteins ; Rats ; Rats, Wistar ; Streptozocin ; toxicity ; Transcription Factors

OBJECTIVETo investigate the effect of aqueous solution of Biophytum sensitivum leaf extract (BSEt) on normal and streptozotocin (STZ)-nicotinamide-induced diabetic rats.

METHODSDiabetes was induced in adult male Wistar rats by the administration of STZ-nicotinamide (40, 110 mg/kg b.w., respectively) intraperitoneally. BSEt (200 mg/kg) was administered to diabetic rats for 28 days. The effect of extract on blood glucose, plasma insulin, total haemoglobin, glycosylated haemoglobin, liver glycogen and carbohydrate metabolism regulating enzymes of liver was studied in diabetic rats.

RESULTSBSEt significantly reduced the blood glucose and glycosylated haemoglobin levels and significantly increased the total haemoglobin, plasma insulin and liver glycogen levels in diabetic rats. It also increased the hexokinase activity and decreased glucose-6-phosphatase, fructose-1, 6-bisphosphatase activities in diabetic rats.

CONCLUSIONSThe results of our study suggest that BSEt possesses a promising effect on STZ-nicotinamide-induced diabetes.

Animals ; Blood Glucose ; analysis ; Diabetes Mellitus, Experimental ; drug therapy ; Enzymes ; analysis ; Glycated Hemoglobin A ; analysis ; Glycogen ; analysis ; Hypoglycemic Agents ; isolation & purification ; therapeutic use ; Insulin ; blood ; Liver ; chemistry ; enzymology ; Male ; Niacinamide ; toxicity ; Oxalidaceae ; chemistry ; Plant Extracts ; isolation & purification ; therapeutic use ; Plant Leaves ; chemistry ; Plasma ; chemistry ; Rats, Wistar ; Streptozocin ; toxicity ; Treatment Outcome

BACKGROUNDThe effect of impaired glucose tolerance (IGT) on cardiac function during the chronic prediabetes state is complicated and plays an important role in clinical outcome. However, the molecular mechanisms are not fully understood. This study was designed to observe cardiac dysfunction in prediabetic rats with IGT and to determine whether glucose metabolic abnormalities, inflammation and apoptosis are linked to it.

METHODSThe IGT rat models were induced by streptozocin, and the heart functions were assessed by echocardiography. Myocardial glucose metabolism was analyzed by glycogen periodic acid-Schiff staining, and the pro-apoptotic effect of IGT was evaluated by TUNEL staining. Additionally, caspase-3 activation, macrophage migration inhibitory factor (MIF) and G-protein coupled receptor kinase 2 (GRK2) were detected by Western blotting in cardiac tissue lysates.

RESULTSArea-under-the-curve of blood glucose in rats injected with streptozotocin was higher than that in controls, increased by 16.28%, 38.60% and 38.61% at 2, 4 and 6 weeks respectively (F = 15.370, P = 0.003). Abnormal cardiac functions and apoptotic cardiomyocytes were observed in the IGT rats, the ejection fraction (EF) being (68.59 ± 6.62)% in IGT rats vs. (81.07 ± 4.59)% in controls (t = 4.020, P = 0.002). There was more glucose which was converted to glycogen in the myocardial tissues of IGT rats, especially in cardiac perivascular tissues. Compared to controls, the cleaved caspase-3, MIF and GRK2 were expressed at higher levels in the myocardial tissues of IGT rats.

CONCLUSIONSIGT in the prediabetes period resulted in cardiac dysfunction linked to abnormal glycogen storage and apoptosis. Additionally, MIF and GRK2 may be involved in the pathogenesis of cardiac dysfunction in prediabetes and their regulation may contribute to the design of novel diagnostic and therapeutic strategies for those who have potential risks for diabetic cardiovascular complications.

Animals ; Apoptosis ; drug effects ; Blotting, Western ; Disease Models, Animal ; Echocardiography ; G-Protein-Coupled Receptor Kinase 2 ; metabolism ; Glucose Intolerance ; chemically induced ; physiopathology ; Glucose Tolerance Test ; In Situ Nick-End Labeling ; Intramolecular Oxidoreductases ; metabolism ; Macrophage Migration-Inhibitory Factors ; metabolism ; Myocardium ; metabolism ; pathology ; Myocytes, Cardiac ; pathology ; Rats ; Streptozocin ; toxicity

OBJECTIVE: The present study aims at determining the stability of a popular type 2 diabetes rat model induced by a high-fat diet combined with a low-dose streptozotocin injection. METHODS: Wistar rats were fed with a high-fat diet for 8 weeks followed by a one-time injection of 25 or 35 mg/kg streptozotocin to induce type 2 diabetes. Then the diabetic rats were fed with regular diet/high-fat diet for 4 weeks. Changes in biochemical parameters were monitored during the 4 weeks. RESULTS: All the rats developed more severe dyslipidemia and hepatic dysfunction after streptozotocin injection. The features of 35 mg/kg streptozotocin rats more resembled type 1 diabetes with decreased body weight and blood insulin. Rats with 25 mg/kg streptozotocin followed by normal diet feeding showed normalized blood glucose level and pancreatic structure, indicating that normal diet might help recovery from certain symptoms of type 2 diabetes. In comparison, diabetic rats fed with high-fat diet presented decreased but relatively stable blood glucose level, and this was significantly higher than that of the control group (P<0.05). CONCLUSIONS This model easily recovers with normal diet feeding. A high-fat diet is suggested as the background diet in future pharmacological studies using this model.
Animals ; Blood Glucose ; metabolism ; Diabetes Mellitus, Experimental ; blood ; etiology ; physiopathology ; Diabetes Mellitus, Type 2 ; blood ; etiology ; physiopathology ; Diet, High-Fat ; adverse effects ; Insulin ; blood ; Lipids ; blood ; Liver ; drug effects ; pathology ; physiopathology ; Male ; Malondialdehyde ; blood ; Oxidative Stress ; Rats ; Rats, Wistar ; Streptozocin ; administration & dosage ; toxicity ; Superoxide Dismutase ; blood ; Uric Acid ; blood

We aimed to elucidate the effect of bilirubin on dyslipidemia and nephropathy in a diabetes mellitus (DM) type I animal model. Sprague-Dawley rats were separated into control, DM, and bilirubin-treated DM (Bil) groups. The Bil group was injected intraperitoneally with 60 mg/kg bilirubin 3 times per week and hepatoma cells were cultured with bilirubin at a concentration of 0.3 mg/dL. The Bil group showed lower serum creatinine levels 5 weeks after diabetes onset. Bilirubin treatment also decreased the amount of mesangial matrix, lowered the expression of renal collagen IV and transforming growth factor (TGF)-beta1, and reduced the level of apoptosis in the kidney, compared to the DM group. These changes were accompanied by decreased tissue levels of hydrogen superoxide and NADPH oxidase subunit proteins. Bilirubin decreased serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), free fatty acids, and triglycerides (TGs), as well as the TG content in the liver tissues. Bilirubin suppressed protein expression of LXRalpha, SREBP-1, SCD-1, and FAS, factors involved in TG synthesis that were elevated in the livers of DM rats and hepatoma cells under high-glucose conditions. In conclusion, bilirubin attenuates renal dysfunction and dyslipidemia in diabetes by suppressing LXRalpha and SREBP-1 expression and oxidative stress.
Animals ; Bilirubin/pharmacology/*therapeutic use ; Cell Line, Tumor ; Creatine/blood ; Diabetes Mellitus, Experimental/chemically induced/complications/*pathology ; Diabetic Nephropathies/*drug therapy/etiology ; Disease Models, Animal ; Kidney/pathology ; Lipoproteins, HDL/blood ; Liver/metabolism ; Male ; Mice ; Mice, Inbred C57BL ; NADPH Oxidase/metabolism ; Orphan Nuclear Receptors/antagonists & inhibitors/genetics/metabolism ; Oxidative Stress/drug effects ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species/metabolism ; Streptozocin/toxicity ; Triglycerides/analysis/*biosynthesis/blood