4-hydroxy-2-nonenal and Diabetes-Mellitus--Type-2

Since the landmark discovery of α,β-unsaturated 4-hydroxyalkenals by Esterbauer and colleagues most studies have addressed the consequences of the tendency of these lipid peroxidation products to form covalent adducts with macromolecules and modify cellular functions. Many studies describe detrimental and cytotoxic effects of 4-hydroxy-2E-nonenal (4-HNE) in myriad tissues and organs and many pathologies. Other studies similarly assigned unfavorable effects to 4-hydroxy-2E-hexenal (4-HHE) and 4-hydroxy-2E,6Z-dodecadienal (4-HDDE). Nutrient overload (e.g., hyperglycemia, hyperlipidemia) modifies lipid metabolism in cells and promotes lipid peroxidation and the generation of α,β-unsaturated 4-hydroxyalkenals. Advances glycation- and lipoxidation end products (AGEs and ALEs) have been associated with the development of insulin resistance and pancreatic beta cell dysfunction and the etiology of type 2 diabetes and its peripheral complications. Less acknowledged are genuine signaling properties of 4-hydroxyalkenals in hormetic processes that provide defense against the consequences of nutrient overload. This review addresses recent findings on such lipohormetic mechanisms that are associated with lipid peroxidation in pancreatic beta cells. This article is part of a Special Issue entitled SI: LIPID OXIDATION PRODUCTS, edited by Giuseppe Poli.

Topics: Aldehydes; Animals; Diabetes Mellitus, Type 2; Diabetic Neuropathies; Glycation End Products, Advanced; Hormesis; Humans; Hyperglycemia; Hyperlipidemias; Insulin Resistance; Insulin-Secreting Cells; Lipid Peroxidation; Oxidative Stress; Phospholipases A2

Peroxidation of polyunsaturated fatty acids is intensified in cells subjected to oxidative stress and results in the generation of various bioactive compounds, of which 4-hydroxyalkenals are prominent. During the progression of type 2 diabetes mellitus, the ensuing hyperglycemia promotes the generation of reactive oxygen species (ROS) that contribute to the development of diabetic complications. It has been suggested that ROS-induced lipid peroxidation and the resulting 4-hydroxyalkenals markedly contribute to the development and progression of these pathologies. Recent findings, however, also suggest that noncytotoxic levels of 4-hydroxyalkenals play important signaling functions in the early phase of diabetes and act as hormetic factors to induce adaptive and protective responses in cells, enabling them to function in the hyperglycemic milieu. Our studies and others' have proposed such regulatory functions for 4-hydroxynonenal and 4-hydroxydodecadienal in insulin secreting β-cells and vascular endothelial cells, respectively. This review presents and discusses the mechanisms regulating the generation of 4-hydroxyalkenals under high glucose conditions and the molecular interactions underlying the reciprocal transition from hormetic to cytotoxic agents.

Topics: Aldehydes; Animals; Diabetes Mellitus, Type 2; Disease Progression; Humans; Lipid Peroxidation; Oxidative Stress; Reactive Oxygen Species; Signal Transduction

The relationships among skeletal muscle lipid peroxidation, intramyocellular lipid content (IMCL), and insulin sensitivity were evaluated in nine insulin-sensitive (IS), 13 insulin-resistant (IR), and 10 adults with type 2 diabetes (T2DM).. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp [glucose disposal rate (GDR)]. Lipid peroxidation was assessed by 4-hydroxynonenal (HNE)-protein adducts and general oxidative stress by protein carbonyl content. All patients were sedentary.. Protein-HNE adducts were elevated 1.6-fold in T2DM compared with IS adults, whereas IR showed intermediate levels of HNE-modified proteins. Protein-HNE adducts correlated with GDR, waist circumference, and body mass index. IMCL was increased by 4.0- and 1.9-fold in T2DM and IR patients, respectively, compared with IS, and was correlated with GDR and waist circumference but not BMI. Protein carbonyls were not different among groups and did not correlate with any of the measured variables. Correlations were detected between IMCL and protein-HNE.. Our data show for the first time that skeletal muscle protein-HNE adducts are related to the severity of insulin resistance in sedentary adults. These results suggest that muscle lipid peroxidation could be involved in the development of insulin resistance.

Topics: Adiposity; Adult; Aldehydes; Blood Glucose; Body Mass Index; Diabetes Mellitus, Type 2; Female; Glucose Clamp Technique; Humans; Insulin Resistance; Lipid Peroxidation; Male; Middle Aged; Muscle, Skeletal; Young Adult

To investigate the effects of propionyl l-carnitine (PLC) on clinical and functional parameters, and markers of the overall oxidation state in patients with peripheral arterial disease (PAD) associated with non-insulin-dependent diabetes mellitus (NIDDM).. Randomised, double-blind, clinical trial, conducted in the Unit of Medical Angiology of the University of Catania.. Seventy-four patients with NIDDM-associated PAD were treated with PLC (2 g/day) or placebo for 12 months.. Ankle/brachial index (ABI) and the distance of pain-free walking were evaluated at baseline, 6 and 12 months. Malondialdehyde, 4-hydroxynonenal, oxidation time of low-density lipoproteins, and nitrite/nitrate ratio were measured as indices of the overall oxidation profiles at baseline and 12 months.. In the PLC group, ABI progressively increased (0.78, 0.83, and 0.88 at 0, 6 and 12 months, respectively). The distance of pain-free walking also improved (366.4, 441.9 and 519.8 m, respectively). In the placebo group, these parameters were relatively unchanged. Significant improvements in all parameters of the oxidative profile were seen in the PLC-treated group, with only minor variations observed in the placebo group.. These results suggest that adjunct therapy with PLC may be warranted in type 2 diabetes-associated PAD.

Topics: Aged; Aldehydes; Ankle; Blood Glucose; Blood Pressure; Brachial Artery; Carnitine; Cholesterol, LDL; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Double-Blind Method; Glycated Hemoglobin; Humans; Malondialdehyde; Middle Aged; Oxidation-Reduction; Pain Measurement; Placebos

Obesity and type 2 diabetes have reached pandemic proportion. ALDH2 (acetaldehyde dehydrogenase 2, mitochondrial) is the key metabolizing enzyme of acetaldehyde and other toxic aldehydes, such as 4-hydroxynonenal. A missense Glu504Lys mutation of the ALDH2 gene is prevalent in 560 million East Asians, resulting in reduced ALDH2 enzymatic activity. We find that male Aldh2 knock-in mice mimicking human Glu504Lys mutation were prone to develop diet-induced obesity, glucose intolerance, insulin resistance, and fatty liver due to reduced adaptive thermogenesis and energy expenditure. We find reduced activity of ALDH2 of the brown adipose tissue from the male Aldh2 homozygous knock-in mice. Proteomic analyses of the brown adipose tissue from the male Aldh2 knock-in mice identifies increased 4-hydroxynonenal-adducted proteins involved in mitochondrial fatty acid oxidation and electron transport chain, leading to markedly decreased fatty acid oxidation rate and mitochondrial respiration of brown adipose tissue, which is essential for adaptive thermogenesis and energy expenditure. AD-9308 is a water-soluble, potent, and highly selective ALDH2 activator. AD-9308 treatment ameliorates diet-induced obesity and fatty liver, and improves glucose homeostasis in both male Aldh2 wild-type and knock-in mice. Our data highlight the therapeutic potential of reducing toxic aldehyde levels by activating ALDH2 for metabolic diseases.

Topics: Aldehyde Dehydrogenase; Aldehyde Dehydrogenase, Mitochondrial; Animals; Diabetes Mellitus, Type 2; Fatty Acids; Fatty Liver; Humans; Male; Mice; Mutation; Obesity; Proteomics

Diabetic retinopathy (DRP) is the formation of edema and small vessels in the retina due to high blood glucose levels. Asprosin is a hormone that stimulates the release of glucose from the liver into the circulation. Considering the relationship between oxidative stress and DRP, our study aimed to determine the levels of the oxidative stress markers 4-hydroxynonenal (4-HNE) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), as well as asprosin, in the blood and aqueous humor (Aq) of patients with and without DRP.. Thirty patients with single-eye DRP and cataract (DRP + C), 30 patients with diabetes mellitus and cataract without DRP (DM + C), and 30 healthy control (CON) participants were enrolled into this retrospective study. Except for healthy controls, Aq and blood samples were taken from these patients during their cataract operation. Asprosin, 4-HNE, and 8-OHdG concentrations were analyzed using enzyme-linked immunosorbent assays.. In patients with DRP, the levels of asprosin, 4-HNE, and 8-OHdG were significantly higher in both Aq and blood samples compared with the group of patients without DRP.. These findings suggest that the measurement of asprosin, 4-HNE, and 8-OHdG levels may support clinicians in determining the risk of DRP development.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aged; Aldehydes; Aqueous Humor; Biomarkers; Cataract; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Enzyme-Linked Immunosorbent Assay; Female; Fibrillin-1; Humans; Male; Middle Aged; Oxidative Stress; Retrospective Studies

Impaired glucose tolerance (IGT) is a risk factor for the development of diabetes and related complications that ensue. Early identification of at-risk individuals might be beneficial to reduce or delay the progression of diabetes and its related complications. Recently, microRNAs emerged as potential biomarkers of diseases. The aim of the present study was to evaluate microRNA-21 as a potential biomarker for the risk of developing diabetes in adults with IGT and to investigate its downstream effects as the generation of reactive oxygen species (ROS), the induction of manganese-superoxide dismutase-2 (SOD2), and the circulating levels of 4-HNE (4-hydroxynonenal).. To evaluate the prognostic and predictive values of plasmatic microRNA-21 in identifying metabolic derangements, we tested a selected cohort (n = 115) of subjects enrolled in the DIAPASON Study, whom were selected on ADA criteria for 2hPG. Statistical analysis was performed using ANOVA or the Kruskal-Wallis test as appropriate. ROC curves were drawn for diagnostic accuracy of the tests; positive and negative predictive values were performed, and Youden's index was used to seek the cut-off optimum truncation point. ROS, SOD2 and 4-HNE were also evaluated.. We observed significant upregulation of microRNA-21 in IGT and in T2D subjects, and microRNA-21 was positively correlated with glycaemic parameters. Diagnostic performance of microRNA-21 was high and accurate. We detected significant overproduction of ROS by electron paramagnetic resonance (EPR), significant accumulation of the lipid peroxidation marker 4-HNE, and defective SOD2 antioxidant response in IGT and newly diagnosed, drug-naïve T2D subjects. In addition, ROC curves demonstrated the diagnostic accuracy of markers used.. our data demonstrate that microRNA-21 is associated with prediabetic status and exhibits predictive value for early detection of glucose imbalances. These data could provide novel clues for miR-based biomarkers to evaluate diabetes.

Topics: Aged; Aldehydes; Blood Glucose; Circulating MicroRNA; Diabetes Mellitus, Type 2; Early Diagnosis; Female; Glucose Intolerance; Humans; Lipid Peroxidation; Male; MicroRNAs; Middle Aged; Oxidative Stress; Predictive Value of Tests; Reactive Oxygen Species; Risk Assessment; Risk Factors; Superoxide Dismutase; Up-Regulation

Obesity-associated impaired fat accumulation in the visceral adipose tissue can lead to ectopic fat deposition and increased risk of insulin resistance and type 2 diabetes mellitus (T2DM). This study investigated whether impaired adipogenesis of omental (OM) adipose tissues and elevated 4-hydroxynonenal (4-HNE) accumulation contribute to this process, and if combined metformin and insulin treatment in T2DM patients could rescue this phenotype.. OM adipose tissues were obtained from forty clinically well characterized obese individuals during weight reduction surgery. Levels of 4-HNE protein adducts, adipocyte size and number of macrophages were determined within these tissues by immunohistochemistry. Adipogenic capacity and gene expression profiles were assessed in preadipocytes derived from these tissues in relation to insulin resistance and in response to 4-HNE, metformin or combined metformin and insulin treatment.. Preadipocytes isolated from insulin resistant (IR) and T2DM individuals exhibited lower adipogenesis, marked by upregulation of anti-adipogenic genes, compared to preadipocytes derived from insulin sensitive (IS) individuals. Impaired adipogenesis was also associated with increased 4-HNE levels, smaller adipocytes and greater macrophage presence in the adipose tissues. Within the T2DM group, preadipocytes from combined metformin and insulin treated subset showed better in vitro adipogenesis compared to metformin alone, which was associated with less presence of macrophages and 4-HNE in the adipose tissues. Treatment of preadipocytes in vitro with 4-HNE reduced their adipogenesis and increased proliferation, even in the presence of metformin, which was partially rescued by the presence of insulin.. This study reveals involvement of 4-HNE in the impaired OM adipogenesis-associated with insulin resistance and T2DM and provides a proof of concept that this impairment can be reversed by the synergistic action of insulin and metformin. Further studies are needed to evaluate involvement of 4-HNE in metabolically impaired abdominal adipogenesis and to confirm benefits of combined metformin-insulin therapy in T2DM patients.

Topics: Adipocytes; Adipogenesis; Adult; Aldehydes; Bariatric Surgery; Cells, Cultured; Diabetes Mellitus, Type 2; Drug Therapy, Combination; Female; Humans; Insulin; Male; Metformin; Middle Aged; Obesity

Amylin is a hormone synthesized and co-secreted with insulin by pancreatic β-cells that crosses the blood-brain barrier and regulates satiety. Amylin from humans (but not rodents) has an increased propensity to aggregate into pancreatic islet amyloid deposits that contribute to β-cell mass depletion and development of type-2 diabetes by inducing oxidative stress and inflammation. Recent studies demonstrated that aggregated amylin also accumulates in brains of Alzheimer's disease (AD) patients, preponderantly those with type-2 diabetes. Here, we report that, in addition to amylin plaques and mixed amylin-Aβ deposits, brains of diabetic patients with AD show amylin immunoreactive deposits inside the neurons. Neuronal amylin formed adducts with 4-hydroxynonenal (4-HNE), a marker of peroxidative membrane injury, and increased synthesis of the proinflammatory cytokine interleukin (IL)-1β. These pathological changes were mirrored in rats expressing human amylin in pancreatic islets (HIP rats) and mice intravenously injected with aggregated human amylin, but not in hyperglycemic rats secreting wild-type non-amyloidogenic rat amylin. In cultured primary hippocampal rat neurons, aggregated amylin increased IL-1β synthesis via membrane destabilization and subsequent generation of 4-HNE. These effects were blocked by membrane stabilizers and lipid peroxidation inhibitors. Thus, elevated circulating levels of aggregated amylin negatively affect the neurons causing peroxidative membrane injury and aberrant inflammatory responses independent of other confounding factors of diabetes. The present results are consistent with the pathological role of aggregated amylin in the pancreas, demonstrate a novel contributing mechanism to neurodegeneration, and suggest a direct, potentially treatable link of type-2 diabetes with AD.

Topics: Aged; Aged, 80 and over; Aldehydes; Alzheimer Disease; Animals; Animals, Newborn; Appetite Depressants; Blood Glucose; Brain; Cells, Cultured; Diabetes Mellitus, Type 2; Disease Models, Animal; Fasting; Female; Hippocampus; Humans; Interleukin-1beta; Islet Amyloid Polypeptide; Islets of Langerhans; Ligation; Lipid Peroxidation; Male; Mice; Rats; Rats, Transgenic

The rising prevalence of type-2 diabetes is becoming a pressing issue based on emerging reports that T2DM can also adversely impact mental health. We have utilized the UCD-T2DM rat model in which the onset of T2DM develops spontaneously across time and can serve to understand the pathophysiology of diabetes in humans. An increased insulin resistance index and plasma glucose levels manifested the onset of T2DM. There was a decrease in hippocampal insulin receptor signaling in the hippocampus, which correlated with peripheral insulin resistance index along the course of diabetes onset (r=-0.56, p<0.01). T2DM increased the hippocampal levels of 4-hydroxynonenal (4-HNE; a marker of lipid peroxidation) in inverse proportion to the changes in the mitochondrial regulator PGC-1α. Disrupted energy homeostasis was further manifested by a concurrent reduction in energy metabolic markers, including TFAM, SIRT1, and AMPK phosphorylation. In addition, T2DM influenced brain plasticity as evidenced by a significant reduction of BDNF-TrkB signaling. These results suggest that the pathology of T2DM in the brain involves a progressive and coordinated disruption of insulin signaling, and energy homeostasis, with profound consequences for brain function and plasticity. All the described consequences of T2DM were attenuated by treatment with the glucagon-like peptide-1 receptor agonist, liraglutide. Similar results to those of liraglutide were obtained by exposing T2DM rats to a food energy restricted diet, which suggest that normalization of brain energy metabolism is a crucial factor to counteract central insulin sensitivity and synaptic plasticity associated with T2DM.

Topics: Aldehydes; Animals; Biomarkers; Blood Glucose; Brain; Crosses, Genetic; Diabetes Mellitus, Type 2; Disease Models, Animal; Energy Metabolism; Glucagon-Like Peptide 1; Hippocampus; Homeostasis; Hypoglycemic Agents; Immunoblotting; Insulin Resistance; Liraglutide; Male; Neuronal Plasticity; Obesity; Rats; Rats, Sprague-Dawley; Rats, Zucker; Receptor, Insulin

Consumption of a high-fructose diet (HFrD) can induce the development of a metabolic syndrome, manifesting as nonalcoholic steatohepatitis (NASH) and/or type 2 diabetes mellitus (T2DM), via a process in which oxidative stress plays a critical role. Peroxiredoxin 4 (PRDX4) is a unique and only known secretory member of the PRDX antioxidant family. However, its putative roles in the development of NASH and/or T2DM have not been investigated.. To elucidate the functions of PRDX4 in a metabolic syndrome, we established a nongenetic mouse model of T2DM by feeding mice a HFrD after injecting a relatively low dose of streptozotocin. Compared with wild-type (WT), human PRDX4 transgenic (Tg) mice exhibited significant improvements in insulin resistance, characterized by a lower glucose and insulin concentration and faster responses in glucose tolerance tests. The liver of Tg also showed less severe vesicular steatosis, inflammation, and fibrosis, along with lower lipid concentrations, lower levels of oxidative stress markers, more decreased expression of hepatic aminotransferase, and more reduced stellate cell activation than those in the WT liver, reminiscent of human early NASH. Hepatocyte apoptosis was also significantly repressed in Tg mice. By contrast, serum adiponectin levels and hepatic adiponectin receptor expression were significantly lower in WT mice, consistent with greater insulin resistance in the peripheral liver tissue compared with Tg mice.. Our data for the first time show that PRDX4 may protect against NASH, T2DM, and the metabolic syndrome by ameliorating oxidative stress-induced injury.

Topics: Adiponectin; Aldehydes; Animals; Apoptosis; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Fatty Liver; Guanosine; Hepatocytes; Humans; Inflammation Mediators; Liver; Male; Mice; Mice, Transgenic; Non-alcoholic Fatty Liver Disease; Oxidative Stress; Peroxiredoxins; Receptors, Adiponectin; T-Lymphocytes; Thiobarbituric Acid Reactive Substances

Although recent studies have proven that renin-angiotensin system (RAS) blockades retard the progression of diabetic nephropathy, the detailed mechanisms of their reno-protective effects on the development of diabetic nephropathy remain uncertain. In rodent models, it has been reported that reactive oxygen species (ROS) are important for intrarenal angiotensinogen (AGT) augmentation in the progression of diabetic nephropathy. However, no direct evidence is available to demonstrate that AGT expression is enhanced in the kidneys of patients with diabetes. To examine whether the expression levels of ROS- and RAS-related factors in kidneys are increased with the progression of diabetic nephropathy, biopsied samples from 8 controls and 27 patients with type 2 diabetes were used. After the biopsy, these patients were diagnosed with minor glomerular abnormality or diabetes mellitus by clinical and pathological findings. The intensities of AGT, angiotensin II (Ang II), 4-hydroxy-2-nonenal (4-HNE), and heme oxygenase-1 (HO-1) were examined by fluorescence in situ hybridization and/or immunohistochemistry. Expression levels were greater in patients with diabetes than in control subjects. Moreover, the augmented intrarenal AGT mRNA expression paralleled renal dysfunction in patients with diabetes. These data suggest the importance of the activated oxidative stress/AGT/RAS axis in the pathogenesis of diabetic nephropathy.

Topics: Adult; Aldehydes; Angiotensinogen; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Heme Oxygenase-1; Humans; Kidney; Male; Oxidative Stress; Reactive Oxygen Species; Renin-Angiotensin System

Type 2 diabetes mellitus (T2DM) is a well-known factor risk for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) in obese patients.. To better understand the association between T2DM and NAFLD, global changes in protein expression in diabetic and non-diabetic obese subjects were assessed by a proteomic approach.. Liver samples were obtained from diabetic and non-diabetic morbid obese subjects (BMI>40 kg/m(2) ). Histological analysis was used to evaluate hepatic steatosis and the degree of anatomopathological alteration. Changes in protein expression were analysed by two-dimentional electrophoresis combined with MALDI-TOF mass spectrometry. Levels of glutathione, carbonyl and 4-HNE protein adducts were used to assess oxidative stress status.. Of 850 proteins analysed, 33 were differentially expressed in T2DM obese subjects. Of these, 27 were unequivocally identified by mass spectrometry. Analysis of protein sets revealed patterns of decreased abundance in mitochondrial enzymes, proteins involved in methione metabolism, and oxidative stress response. Accordingly, T2DM subjects showed decreased levels of glutathione, the antioxidant byproduct of methionine metabolism via the transsulfuration pathway, and higher levels of protein and lipid oxidative damage. Changes in detoxyfing enzymes, carbohydrate metabolism, proteasome subunits and retinoic acid synthesis were also found.. The results suggest alterations in mitochondrial function and methionine metabolism as potential contributing factors to increased oxidative stress in liver of obese diabetic patients which may be influencing the development of NAFLD and NASH.

Topics: Adult; Aldehydes; Biomarkers; Biopsy; Diabetes Mellitus, Type 2; Electrophoresis, Gel, Two-Dimensional; Fatty Liver; Female; Glutathione; Humans; Liver; Methionine; Middle Aged; Mitochondria, Liver; Non-alcoholic Fatty Liver Disease; Obesity, Morbid; Oxidative Stress; Protein Carbonylation; Proteins; Proteomics; Severity of Illness Index; Spain; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Redox-sensitive stress kinases and heat shock protein 72 (Hsp72) have been considered to be associated with the development of type 2 diabetes in skeletal muscle. However, the effect of exercise training on skeletal muscle of type 2 diabetic models is largely unknown. The purpose of this study was to investigate the effect of 12 weeks of exercise training on gastrocnemius of type 2 diabetic rats, by examining the activation of c-Jun N-terminal kinase (JNK), the nuclear factor B (NF-B) pathway and Hsp72. Total hydroperoxide and 4-hydroxynoneal, as oxidative stress markers, were also examined. Otsuka Long-Evans Tokushima fatty (OLEFT) rats were randomly divided into an exercise training group (Ex-OLETF, n = 8) and a sedentary group (Sed-OLETF, n = 8), while Long-Evans Tokushima Otsuka (LETO) rats were used as a control group (Con-LETO, n = 5). The Ex-OLETF rats were trained on a treadmill five times a week for 12 weeks. The levels of hydroperoxide and 4-hydroxynoneal in both Ex-OLETF and Sed-OLETF were significantly higher compared with Con-LETO, but there was no difference between Ex-OLETF and Sed-OLETF. Levels of inhibitor B kinase, JNK activation and p65 nuclear translocation followed a similar pattern to that observed in oxidative stress markers. The level of Hsp72 in Ex-OLETF was increased by exercise training, but it did not reach the level observed in Con-LETO. The NF-B DNA binding activity in Sed-OLETF was significantly higher compared with Con-LETO. Although it was not statistically significant, exercise training in Ex-OLETF showed a trend to reduce the activation of NF-B DNA binding activity compared with Sed-OLETF (P = 0.104). Our findings indicate that exercise training improves basal glucose metabolism without a change in stress kinases, and that nuclear regulation of NF-B activity in diabetic muscle could be regulated independently of the cytosolic pathway. Our study also suggests a possibility that exercise-induced Hsp72 serves as a protective mechanism in skeletal muscle of OLETF rats.

Topics: Aldehydes; Animals; Blood Glucose; Diabetes Mellitus, Type 2; Glucose Tolerance Test; HSP72 Heat-Shock Proteins; Hydrogen Peroxide; I-kappa B Kinase; JNK Mitogen-Activated Protein Kinases; Motor Activity; Muscle, Skeletal; Phosphorylation; Physical Conditioning, Animal; Rats; Rats, Inbred OLETF; Transcription Factor RelA

Previous studies show that polyunsaturated fatty acids (PUFAs) increase the insulin secretory capacity of pancreatic β-cells. We aimed at identifying PUFA-derived mediators and their cellular targets that are involved in the amplification of insulin release from β-cells preexposed to high glucose levels.. The content of fatty acids in phospholipids of INS-1E β-cells was determined by lipidomics analysis. High-performance liquid chromatography was used to identify peroxidation products in β-cell cultures. Static and dynamic glucose-stimulated insulin secretion (GSIS) assays were performed on isolated rat islets and/or INS-1E cells. The function of peroxisome proliferator-activated receptor-δ (PPAR-δ) in regulating insulin secretion was investigated using pharmacological agents and gene expression manipulations.. High glucose activated cPLA(2) and, subsequently, the hydrolysis of arachidonic and linoleic acid (AA and LA, respectively) from phospholipids in INS-1E cells. Glucose also increased the level of reactive oxygen species, which promoted the peroxidation of these PUFAs to generate 4-hydroxy-2E-nonenal (4-HNE). The latter mimicked the GSIS-amplifying effect of high glucose preexposure and of the PPAR-δ agonist GW501516 in INS-1E cells and isolated rat islets. These effects were blocked with GSK0660, a selective PPAR-δ antagonist, and the antioxidant N-acetylcysteine or by silencing PPAR-δ expression. High glucose, 4-HNE, and GW501516 also induced luciferase expression in a PPAR-δ-mediated transactivation assay. Cytotoxic effects of 4-HNE were observed only above the physiologically effective concentration range.. Elevated glucose levels augment the release of AA and LA from phospholipids and their peroxidation to 4-HNE in β-cells. This molecule is an endogenous ligand for PPAR-δ, which amplifies insulin secretion in β-cells.

Topics: Aldehydes; Animals; Cell Line; Diabetes Mellitus, Type 2; Fatty Acids, Unsaturated; Gene Silencing; Gerbillinae; Group IV Phospholipases A2; Humans; Hyperglycemia; Insulin; Insulin Secretion; Insulin-Secreting Cells; Islets of Langerhans; Lipid Peroxidation; Male; PPAR delta; Rats; Rats, Wistar; Reactive Oxygen Species; Recombinant Proteins; Signal Transduction; Tissue Culture Techniques

Post-prandial hyperglycemia seems to play a pivotal role in the pathogenesis of the cardiovascular complications of diabetes mellitus, as it leads to an oxidative stress which in turn causes a reduced NO bioavailability. These conditions produce an endothelial activation.. The aim of this study was to assure that the administration of N-acetylcysteine (NAC), thiolic antioxidant, is able to decrease the oxidation status and endothelial activation after a high-glucose content meal.. Ten patients with Type 2 diabetes mellitus (DMT2) (Group 1) and 10 normal subjects (Group 2) were studied. They assumed a high-glucose content meal without (phase A) or after (phase B) the administration of NAC. Glycemia, insulinemia, intercellular adhesion molecule 1, vascular adhesion molecule 1 (VCAM-1), E-selectin, malonaldehyde (MDA), and 4-hydroxynonenal (HNE) were assessed at -30, 0, +30, +60, +90, +120, and +180 min with respect to the meal consumption.. During the phase A in Group 1, only HNE and MDA levels increased after the meal assumption; all parameters remained unchanged in Group 2. During the phase B, in Group 1, HNE, MDA, VCAM-1, and E-selectin levels after the meal were lower than those in phase A, while no change for all variables were observed in Group 2.. A high-glucose meal produces an increase in oxidation parameters in patients with DMT2. The administration of NAC reduces the oxidative stress and, by doing so, reduces the endothelial activation. In conclusion, NAC could be efficacious in the slackening of the progression of vascular damage in DMT2.

Topics: Acetylcysteine; Aged; Aldehydes; Case-Control Studies; Diabetes Mellitus, Type 2; E-Selectin; Endothelium, Vascular; Female; Free Radical Scavengers; Glucose; Glycemic Index; Humans; Insulin; Male; Malondialdehyde; Middle Aged; Oxidation-Reduction; Oxidative Stress; Postprandial Period; Vascular Cell Adhesion Molecule-1

Alzheimer's disease (AD) is associated with brain insulin resistance and insulin deficiency, whereas Type 2 diabetes mellitus (T2DM) is associated with peripheral insulin resistance. This study assesses the degree to which T2DM causes AD-type neurodegeneration. In a C57BL/6 mouse model of obesity and T2DM, we characterized the histopathology, gene expression, and insulin and insulin-like growth factor (IGF)-receptor binding in temporal lobe. High fat diet (HFD) feeding for 16 weeks doubled mean body weight, caused T2DM, and marginally reduced mean brain weight. These effects were associated with significantly increased levels of tau, IGF-I receptor, insulin receptor substrate-1 (IRS-1), IRS-4, ubiquitin, glial fibrillary acidic protein, and 4-hydroxynonenol, and decreased expression of beta-actin. HFD feeding also caused brain insulin resistance manifested by reduced BMAX for insulin receptor binding, and modestly increased brain insulin gene expression. However, HFD-fed mouse brains did not exhibit AD histopathology, increases in amyloid-beta or phospho-tau, or impairments in IGF signaling or acetylcholine homeostasis. Obesity and T2DM cause brain atrophy with insulin resistance, oxidative stress, and cytoskeleton degradation, but the absence of many features that typify AD suggests that obesity and T2DM may contribute to, but are not sufficient to cause AD.

Topics: Actins; Adaptor Proteins, Signal Transducing; Aldehydes; Alzheimer Disease; Amyloid beta-Peptides; Animals; Atrophy; Brain; Diabetes Mellitus, Type 2; DNA Primers; Enzyme-Linked Immunosorbent Assay; Gene Expression; Glial Fibrillary Acidic Protein; Insulin Receptor Substrate Proteins; Insulin Resistance; Insulin-Like Growth Factor I; Mice; Mice, Inbred C57BL; Nerve Degeneration; Obesity; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Ubiquitin

Aldose reductase (AR) is the rate-limiting enzyme of the polyol pathway. In diabetes, it is related to microvascular complications. We discovered AR expression in foam cells by gene chip screening and hypothesized that it may be relevant in atherosclerosis.. AR gene expression and activity were found to be increased in human blood monocyte-derived macrophages during foam cell formation induced by oxidized LDL (oxLDL, 100 microg/mL). AR activity as photometrically determined by NADPH consumption was effectively inhibited by the AR inhibitor epalrestat. oxLDL-dependent AR upregulation was further increased under hyperglycemic conditions (30 mmol/L D-glucose) as compared to osmotic control, suggesting a synergistic effect of hyperlipidemia and hyperglycemia. AR was also upregulated by 4-hydroxynonenal, a constituent of oxLDL. Upregulation was blocked by an antibody to CD36. AR inhibition resulted in reduction of oxLDL-induced intracellular oxidative stress as determined by 2'7'-dichlorofluoresceine diacetate (H2DCFDA) fluorescence, indicating that proinflammatory effects of oxLDL are partly mediated by AR. Immunohistochemistry showed AR expression in CD68+ human atherosclerotic plaque macrophages.. These data show that oxLDL-induced upregulation of AR in human macrophages is proinflammatory in foam cells and may represent a potential link among hyperlipidemia, atherosclerosis, and diabetes mellitus.

Topics: Adult; Aldehyde Reductase; Aldehydes; Atherosclerosis; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Female; Foam Cells; Humans; Hyperlipidemias; Lipoproteins, LDL; Male; Oligonucleotide Array Sequence Analysis; Oxidative Stress; Rhodanine; Risk Factors; Thiazolidines; Up-Regulation

This study was undertaken to reveal the role of NAD(P)H oxidase in increased oxidative stress in islets of Type 2 diabetes. Immunostaining analysis showed that staining intensities of NAD(P)H oxidase components, gp91phox and p22phox, significantly increased in islets of animal models of Type 2 diabetes, OLETF rats (60 weeks of age) and db/db mice (14 weeks of age), compared with age-matched controls, respectively, correlating with increased levels of oxidative stress marker, 8-hydroxy-deoxyguanosine or 4-hydroxy-2-nonenal modified protein. In db/db mice, oral administration of angiotensin II Type 1 receptor antagonist valsartan (5 mg/kg) for 4 weeks significantly attenuated the increased expression of gp91phox and p22phox together with inhibition of oxidative stress and partially restored decreased insulin contents in islets. Angiotensin II-related increased expression of NAD(P)H oxidase may play an important role in increased oxidative stress in islets of Type 2 diabetes. This mechanism may be a novel therapeutic target for preventing beta-cell damage.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Administration, Oral; Aldehydes; Angiotensin II; Angiotensin II Type 1 Receptor Blockers; Angiotensins; Animals; Body Weight; Deoxyguanosine; Diabetes Mellitus, Type 2; Disease Models, Animal; Insulin; Islets of Langerhans; Membrane Glycoproteins; Membrane Transport Proteins; Mice; Mice, Inbred C57BL; NADPH Oxidase 2; NADPH Oxidases; Oxidative Stress; Phosphoproteins; Rats; Rats, Inbred OLETF; Rats, Long-Evans; Tetrazoles; Time Factors; Valine; Valsartan

Carbonyl stress is one of the important mechanisms of tissue damage in vascular complications of diabetes. In the present study, we observed that the plasminogen activator inhibitor-1 (PAI-1) levels in serum and its gene expression in adipose tissue were up-regulated in aged OLETF rats, model animals of obese type 2 diabetes. To study the mechanism of PAI-1 up-regulation, we examined the effect of advanced glycation end products (AGEs) and the product of lipid peroxidation (4-hydroxy-2-nonenal (HNE)), both of which are endogenously generated under carbonyl stress. Stimulation of primary white adipocytes by either AGE or HNE resulted in the elevation of PAI-1 in culture medium and at mRNA levels. The up-regulation of PAI-1 was also observed by incubating the cells in high glucose medium (30 mm, 48 h). The stimulatory effects by AGE or high glucose were inhibited by antioxidant, pyrrolidine dithiocarbamate, and reactive oxygen scavenger, probucol, suggesting a pivotal role of oxidative stress in white adipocytes. We also found that the effect by HNE was inhibited by antioxidant, N-acetylcysteine and that a specific inhibitor of glutathione biosynthesis, l-buthionine-S,R-sulfoximine, augmented the effect of subthreshold effect of HNE. Bioimaging of reactive oxygen species (ROS) by a fluorescent indicator, 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate, revealed ROS production in white adipocytes treated with AGE or HNE. These results suggest that cellular carbonyl stress induced by AGEs or HNE may stimulate PAI-1 synthesis in and release from adipose tissues through ROS formation.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Acetylcysteine; Adipocytes; Aldehydes; Animals; Antioxidants; Buthionine Sulfoximine; Cells, Cultured; Deoxyguanosine; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Free Radical Scavengers; Glycation End Products, Advanced; Lipid Peroxidation; Male; NF-kappa B; Oxidative Stress; Plasminogen Activator Inhibitor 1; Rats; Rats, Inbred OLETF; Reactive Oxygen Species; RNA, Messenger; Up-Regulation

Oxidative stress has been implicated in pathogenesis of diabetic retinopathy. It has been hypothesized that hyperglycaemia may damage vascular endothelium and retina by inducing the synthesis of oxidant reactive species. The aim of the present study was to estimate lipid peroxidation by detecting the concentration of malondialdehyde and 4-hydroxynonenal in diabetic patients with retinopathy, subjects without retinopathy and the reference group. Sixty-one patients were studied, including 30 patients with severe non-proliferative retinopathy in NIDDM and 31 diabetic patients without retinopathy. The reference group were 11 systemic healthy patients. Concentration of malondialdehyde and 4-hydroxynonenal was measured in plasma sample using a Lipid peroxidation Assay Kit (Calbiochem-Novabiochem Corp.). The concentration of lipid peroxidation products in patients with retinopathy was statistically significantly elevated in comparison to diabetic patients without retinopathy (p < 0.001) and the reference group (p < 0.001). We do not notice any significant differences in levels of MDA and 4-HNE between patients without diabetic retinopathy and the reference group. In view of our results we can conclude that oxidative stress is an important risk factor in the development of diabetic retinopathy.

Topics: Aldehydes; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Humans; Lipid Peroxidation; Malondialdehyde; Oxidative Stress; Reference Values; Retina

4-Hydroxy-2-nonenal (HNE) is one of the major lipid peroxidation products with cytotoxic and mutagenic activity. It further reacts with protein residues such as histidine to generate stable Michael adducts. To evaluate the status of oxidative stress in the serum of type 2 diabetes mellitus, we constructed a sandwich enzyme-linked immunosorbent assay to measure serum HNE-modified albumin by the use of a specific monoclonal antibody (HNEJ-2) against HNE-histidine adducts as well as an antibody against human serum albumin. Serum of type 2 diabetes outpatients revealed significantly higher levels of HNE-modified albumin (736.1 +/- 34.2 pmol/ml, n = 54) than the matched nondiabetics (611.4 +/- 39.1 pmol/ml, n = 30; means +/- SEM; p = 0.018). However, no significant correlation was observed in diabetic outpatients between the levels of HNE-modified albumin and clinical parameters such as fasted blood glucose, HbA1c, diabetes duration, or complications. Our data demonstrated the increased formation of serum HNE-modified albumin in type 2 diabetic outpatients in the milieu between liver and vascular lumina, indicating the presence of oxidative stress.

Topics: Aged; Aldehydes; Case-Control Studies; Diabetes Mellitus, Type 2; Enzyme-Linked Immunosorbent Assay; Female; Humans; Lipid Peroxidation; Male; Middle Aged; Oxidative Stress; Serum Albumin

Reactive oxygen species are involved in a diversity of biological phenomena such as inflammation, carcinogenesis, aging, and atherosclerosis. We and other investigators have shown that the level of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker for oxidative stress, is increased in either the urine or the mononuclear cells of the blood of type 2 diabetic patients. However, the association between type 2 diabetes and oxidative stress in the pancreatic beta-cells has not been previously described. We measured the levels of 8-OHdG and 4-hydroxy-2-nonenal (HNE)-modified proteins in the pancreatic beta-cells of GK rats, a model of nonobese type 2 diabetes. Quantitative immunohistochemical analyses with specific antibodies revealed higher levels of 8-OHdG and HNE-modified proteins in the pancreatic beta-cells of GK rats than in the control Wistar rats, with the levels increasing proportionally with age and fibrosis of the pancreatic islets. We further investigated whether the levels of 8-OHdG and HNE-modified proteins would be modified in the pancreatic beta-cells of GK rats fed with 30% sucrose solution or 50 ppm of voglibose (alpha-glucosidase inhibitor). In the GK rats, the levels of 8-OHdG and HNE-modified proteins, as well as islet fibrosis, were increased by sucrose treatment but reduced by voglibose treatment. These results indicate that the pancreatic beta-cells of GK rats are oxidatively stressed, and that chronic hyperglycemia might be responsible for the oxidative stress observed in the pancreatic beta-cells.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Aldehydes; Animals; Blood Glucose; Deoxyguanosine; Diabetes Mellitus, Type 2; Enzyme Inhibitors; Hyperglycemia; Immunohistochemistry; Inositol; Insulin; Islets of Langerhans; Oxidative Stress; Proteins; Rats; Rats, Inbred Strains; Solutions; Sucrose