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

β-cell failure coupled with insulin resistance plays a key role in the development of type 2 diabetes mellitus (T2DM). Changed adipokines in circulating level form a remarkable link between obesity and both β-cell failure and insulin resistance. Some adipokines have beneficial effects,whereas others have detrimental properties. The overall contribution of adipokines to β-cell failure mainly depends on the interactions among adipokines. This article reviews the role of individual adipokines such as leptin,adiponectin,and resistin in the function,proliferation,death,and failure of β-cells. Future studies focusing on the combined effects of adipokines on β-cells failure may provide new insights in the treatment of T2DM.
Adipokines ; metabolism ; Adiponectin ; metabolism ; Diabetes Mellitus, Type 2 ; physiopathology ; Humans ; Insulin Resistance ; Insulin-Secreting Cells ; pathology ; Leptin ; metabolism ; Obesity ; Resistin ; metabolism

Prolonged P-wave duration has been observed in diabetes. However, the underlying mechanisms remain unclear. The aim of this study was to elucidate the possible mechanisms. A rat model of type 2 diabetes mellitus (T2DM) was used. P-wave durations were obtained using surface electrocardiography and sizes of the left atrium were determined using echocardiography. Cardiac inward rectifier K+ currents (I(k1)), Na+ currents (I(Na)), and action potentials were recorded from isolated left atrial myocytes using patch clamp techniques. Left atrial tissue specimens were analyzed for total connexin-40 (Cx40) and connexin-43 (Cx43) expression levels on western-blots. Specimens were also analyzed for Cx40 and Cx43 distribution and interstitial fibrosis by immunofluorescent and Masson trichrome staining, respectively. The mean P-wave duration was longer in T2DM rats than in controls; however, the mean left atrial sizes of each group of rats were similar. The densities of I(k1) and I(Na) were unchanged in T2DM rats compared to controls. The action potential duration was longer in T2DM rats, but there was no significant difference in resting membrane potential or action potential amplitude compared to controls. The expression level of Cx40 protein was significantly lower, but Cx43 was unaltered in T2DM rats. However, immunofluorescent labeling of Cx43 showed a significantly enhanced lateralization. Staining showed interstitial fibrosis was greater in T2DM atrial tissue. Prolonged P-wave duration is not dependent on the left atrial size in rats with T2DM. Dysregulation of Cx40 and Cx43 protein expression, as well as fibrosis, might partly account for the prolongation of P-wave duration in T2DM.
Action Potentials ; Animals ; Blotting, Western ; Connexin 43/metabolism ; Connexins/metabolism ; Diabetes Mellitus, Type 2/*physiopathology ; Disease Models, Animal ; Echocardiography ; Electrocardiography ; Fibrosis/pathology ; Heart Atria/*diagnostic imaging/physiopathology ; In Vitro Techniques ; Male ; Membrane Potentials ; Microscopy, Fluorescence ; Patch-Clamp Techniques ; Potassium Channels/metabolism ; Rats ; Rats, Wistar

PURPOSE: Diabetic nephropathy is a serious complication of type 2 diabetes mellitus, and delaying the development of diabetic nephropathy in patients with diabetes mellitus is very important. In this study, we investigated inflammation, oxidative stress, and lipid metabolism to assess whether curcumin ameliorates diabetic nephropathy. MATERIALS AND METHODS: Animals were divided into three groups: Long-Evans-Tokushima-Otsuka rats for normal controls, Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats for the diabetic group, and curcumin-treated (100 mg/kg/day) OLETF rats. We measured body and epididymal fat weights, and examined plasma glucose, adiponectin, and lipid profiles at 45 weeks. To confirm renal damage, we measured albumin-creatinine ratio, superoxide dismutase (SOD), and malondialdehyde (MDA) in urine samples. Glomerular basement membrane thickness and slit pore density were evaluated in the renal cortex tissue of rats. Furthermore, we conducted adenosine monophosphate-activated protein kinase (AMPK) signaling and oxidative stress-related nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling to investigate mechanisms of lipotoxicity in kidneys. RESULTS: Curcumin ameliorated albuminuria, pathophysiologic changes on the glomerulus, urinary MDA, and urinary SOD related with elevated Nrf2 signaling, as well as serum lipid-related index and ectopic lipid accumulation through activation of AMPK signaling. CONCLUSION: Collectively, these findings indicate that curcumin exerts renoprotective effects by inhibiting renal lipid accumulation and oxidative stress through AMPK and Nrf2 signaling pathway.
Albuminuria ; Animals ; Anti-Inflammatory Agents, Non-Steroidal/*therapeutic use ; Curcumin/*pharmacology ; Diabetes Mellitus, Type 2/*metabolism/urine ; Diabetic Nephropathies/complications/*drug therapy/metabolism/pathology ; Gene Expression/drug effects ; Inflammation ; Kidney/drug effects/metabolism/physiopathology ; Kidney Glomerulus/metabolism/physiopathology ; Lipid Metabolism/*drug effects ; Male ; Malondialdehyde/metabolism/urine ; Oxidative Stress/*drug effects ; Rats ; Rats, Inbred OLETF ; Rats, Long-Evans ; Superoxide Dismutase/metabolism

BACKGROUNDLittle attention has been paid to the role of subcortical deep gray matter (SDGM) structures in type 2 diabetes mellitus (T2DM)-induced cognitive impairment, especially hippocampal subfields. Our aims were to assess the in vivo volumes of SDGM structures and hippocampal subfields using magnetic resonance imaging (MRI) and to test their associations with cognitive performance in T2DM.

METHODSA total of 80 T2DM patients and 80 neurologically unimpaired healthy controls matched by age, sex and education level was enrolled in this study. We assessed the volumes of the SDGM structures and seven hippocampal subfields on MRI using a novel technique that enabled automated volumetry. We used Mini-Mental State Examination and Montreal Cognitive Assessment (MoCA) scores as measures of cognitive performance. The association of glycosylated hemoglobin (HbA1c) with SDGM structures and neuropsychological tests and correlations between hippocampal subfields and neuropsychological tests were assessed by partial correlation analysis in T2DM.

RESULTSBilaterally, the hippocampal volumes were smaller in T2DM patients, mainly in the CA1 and subiculum subfields. Partial correlation analysis showed that the MoCA scores, particularly those regarding delayed memory, were significantly positively correlated with reduced hippocampal CA1 and subiculum volumes in T2DM patients. Additionally, higher HbA1c levels were significantly associated with poor memory performance and hippocampal atrophy among T2DM patients.

CONCLUSIONSThese data indicate that the hippocampus might be the main affected region among the SDGM structures in T2DM. These structural changes in the hippocampal CA1 and subiculum areas might be at the core of underlying neurobiological mechanisms of hippocampal dysfunction, suggesting that degeneration in these regions could be responsible for memory impairments in T2DM patients.

Aged ; CA1 Region, Hippocampal ; pathology ; physiopathology ; Diabetes Mellitus, Type 2 ; pathology ; physiopathology ; Female ; Hippocampus ; pathology ; physiopathology ; Humans ; Magnetic Resonance Imaging ; Male ; Memory Disorders ; etiology ; pathology ; Middle Aged ; Neuropsychological Tests

OBJECTIVETo observe the dynamic expression of calcium-sensing receptor(CaSR) in myocardium of diabetic rats.

METHODSThirty male Wistar rats were randomly divided into 3 groups including control, diabetic-4 week and diabetic-8 week groups(n = 10). The type 2 diabetes mellitus models were established by intraperitoneal injection of streptozotocin (STZ, 30 mg/kg) after high-fat and high-sugar diet for one month. The cardiac morphology was observed by electron microscope. Western blot analyzed the expression of CaSR, phospholamban (PLN), a calcium handling regulator, and Ca+-ATPase(SERCA) in cardiac tissues.

RESULTSCompared with control group, the expressions of CaSR and SERCA were decreased, while the expression of PLN was significantly increased in a time-dependent manner in diabetic groups. Meanwhile diabetic rats displayed abnormal cardiac structure.

CONCLUSIONThese results indicate that the CaSR expression of myocardium is reduced in the progression of DCM, and its potential mechanism may be related to the imnaired intracellular calcium homeostasis.

Animals ; Calcium-Binding Proteins ; metabolism ; Diabetes Mellitus, Experimental ; complications ; Diabetes Mellitus, Type 2 ; Diabetic Cardiomyopathies ; metabolism ; physiopathology ; Disease Progression ; Heart ; physiopathology ; Male ; Myocardium ; metabolism ; pathology ; Rats ; Rats, Wistar ; Receptors, Calcium-Sensing ; metabolism ; Sarcoplasmic Reticulum Calcium-Transporting ATPases ; metabolism ; Streptozocin

BACKGROUNDIntensive insulin therapy has been found to lessen the progress of diabetic retinopathy (DR) to some extent, while it has also been implicated to be responsible for decrease of DR. We investigated visual function and morphological changes in the macular area in short-term follow-up of patients with type 2 diabetes mellitus after intensive insulin therapy.

METHODSThis was a prospective clinical study of nonproliferative DR patients (102 eyes, 120 patients) undergoing intensive insulin therapy. The Contrast Glare Tester (Takagi CGT-1000) was used to examine contrast sensitivity (CS) and Heidelberg Retina Tomograph (HRT) II and Stratus Model 3000 OCT were used to observe the changes of morphology in the macular area. Follow-up times were pre-intensive therapy, 3 and 6 months post-intensive therapy.

RESULTSCS at low and middle frequencies was higher at 3 and 6 months post-therapy compared with pre-therapy (P < 0.05). Significant differences in CS at low frequency were found between 6 and 3 months post-therapy (P < 0.05). Macular edema index was lower in the first, second, and third rings of the macular area after intensive therapy compared with pre-therapy (P < 0.05). Compared with 3 months post-therapy, the macular edema index was lower in the first, second, and third rings of the macular area at 6 months post-therapy (P > 0.05). No significant differences in the thickness of the first, second, and third rings of the macular area were detected between 3 and 6 months post-therapy and pre-therapy (P > 0.05).

CONCLUSIONCS and macular edema indexes were significantly improved in nonproliferative diabetic retinopathy patients after intensive insulin therapy, but thickness of the macular area was unchanged.

Diabetes Mellitus, Type 2 ; drug therapy ; pathology ; physiopathology ; Follow-Up Studies ; Humans ; Insulin ; therapeutic use ; Macula Lutea ; pathology ; Middle Aged ; Prospective Studies ; Tomography, Optical Coherence ; Vision, Ocular ; physiology

OBJECTIVETo analyze the biochemical and pathological changes in mice with type 2 diabetes mellitus (T2DM) induced by high-fat diet combined with low-dose streptozotocin (STZ) injections.

METHODSC57BL/6J mice were divided randomly into normal control group (NC group), high-fat diet group (HC group) and high-fat diet plus STZ group (HC+STZ group). The mice were fed on normal chow or a high-fat diet for 1 month before two introperitoneal injections of STZ (40 mg/kg) or citrate buffer with an interval of 24 h as appropriate. Fasting blood glucose (FBG) was detected every week for 4 weeks, and oral glucose tolerance test (OGTT) was performed one month after the injections, after which the biochemical profiles, islet and liver were evaluated by immunohistochemical and pathological analysis.

RESULTSIn HC+STZ group, FBG was above the cutoff value (13.89 mmol/L) in 75% of the mice at 1 week after STZ injections and in all the mice at two weeks except for the death of 1 mouse, with a success rate of modeling of 91.3%. FBG in HC group, though slightly higher than that in NC group, remained normal (6.8 mmol/L). The body weight in HC+STZ and HC groups was significantly higher than that in NC group after feeding but without obvious increases after the injections (P<0.01). Blood glucose in HC+STZ group at 0.5 to 2 h after OGTT and the area under curve (AUC) were higher than those in NC and HC groups (P<0.01); the AUC in HC group was a also higher than that in NC group (P<0.05). Plasma creatinine was significantly higher in HC+STZ group than in NC (P<0.01) and HC (P<0.05) groups. Insulin secretion by the islets decreased obviously in HC+STZ and HC group. The mice in HC+STZ group showed atrophy, fibrosis, and vacuolization in the islets with mild fatty liver but no visible renal pathologies.

CONCLUSIONHigh-fat diet and low-dose STZ injections can induce T2DM in mice with very similar biochemical and pathological changes to human T2DM and with such complications as fatty liver.

Animals ; Blood Glucose ; Body Weight ; Diabetes Mellitus, Type 2 ; physiopathology ; Diet, High-Fat ; Fatty Liver ; physiopathology ; Glucose Tolerance Test ; Insulin ; Insulin Resistance ; Islets of Langerhans ; pathology ; Kidney ; pathology ; Mice ; Mice, Inbred C57BL ; Streptozocin

The aim of the present study is to investigate the effects of sequoyitol (Seq) on expression of eNOS and NOX4 in aortas of type 2 diabetic rats. Type 2 diabetic rats induced by high fat and high sugar diet and low dose of streptozotocin (STZ, 35 mg x kg(-1)) and were administered Seq (12.5, 25 and 50 mg x kg(-1) x d(-1)) for 6 weeks. The fasting blood glucose (FBG) and body weight were tested. Acetylcholine (Ach) induced endothelium-dependent relaxation and sodium nitroprusside (SNP) induced endothelium-independent relaxation were measured in aortas for estimating endothelial function. Aortic morphological change was observed with HE staining. The level of serum insulin was measured by radioimmunoassay. The total antioxidative capacity (T-AOC), malondialdehyde (MDA) and NO levels in aortas were determined according to the manufacturer's instructions. In addition, the expressions of eNOS and NOX4 in aortas were measured by immunohistochemisty, real-time PCR or Western blotting. The results showed that Seq significantly decreased FBG and insulin resistance, and improved aortic endothelium-dependent vasorelaxation function. The expressions of NOX4 and MDA content were obviously decreased, while the expression of eNOS, the levels of NO and T-AOC increased significantly in aortas of diabetic rats with Seq treatment. In conclusion, Seq protects against aortic endothelial dysfunction of type 2 diabetic rats through down-regulating expression of NOX4 and up-regulating eNOS expression.
Animals ; Aorta ; metabolism ; pathology ; Blood Glucose ; metabolism ; Body Weight ; Diabetes Mellitus, Experimental ; chemically induced ; metabolism ; physiopathology ; Diabetes Mellitus, Type 2 ; chemically induced ; metabolism ; physiopathology ; Hypoglycemic Agents ; pharmacology ; Inositol ; analogs & derivatives ; pharmacology ; Insulin ; blood ; Insulin Resistance ; Male ; Malondialdehyde ; metabolism ; NADPH Oxidase 4 ; NADPH Oxidases ; metabolism ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase Type III ; metabolism ; Oxidation-Reduction ; drug effects ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Vasodilation ; drug effects

Diabetes mellitus (DM) is characterized by hyperglycemia and disturbances of carbohydrate and fat metabolism resulted from an absolute or relative deficiency of insulin and insulin resistance. Recent studies indicate that oxidative stress may have a central role in the pathogenesis of type 2 diabetes. Currently, the diagnosis of body oxidative stress level mainly depends on the detection of oxidative stress markers including reactive oxygen species (ROS), reactive nitrogen species (RNS) and lipid peroxide in clinical and experimental studies with methods combining physical and chemical means. The mechanism underlying oxidative stress-induced diabetes mainly may be through two ways. Firstly oxidative stress damages the normal function of islet β cells, through the destruction of mitochondrial structure and inducing apoptosis, activation of nuclear transcription factor kappa B (NF-κB) signaling pathway, causing cell inflammatory response, and reducing insulin synthesis and secretion by inhibiting pancreatic and duodenal homeobox 1 (PDX-1) nuclear cytoplasm translocation as well as inhibiting energy metabolism; Secondly, oxidative stress induces insulin resistance by interfering physiological activities related to insulin signaling including phosphorylation of insulin receptor (InsR) and insulin receptor substrate (IRS), the activation of phosphatidylinositol 3-kinase (PI3K) and the translocation of glucose transporter 4 (GLUT4), as well as injuring the cytoskeleton. Studying the role of oxidative stress in the pathogenesis of diabetes not only helps to reveal the pathogenesis of diabetes, but also provides a theoretical basis for the prevention and treatment of diabetes.
Apoptosis ; Diabetes Mellitus, Type 2 ; physiopathology ; Humans ; Insulin ; physiology ; Insulin Resistance ; Mitochondria ; pathology ; NF-kappa B ; metabolism ; Oxidative Stress ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; Reactive Oxygen Species ; metabolism ; Signal Transduction