The effect of diabetes on the activities of the peroxide metabolism enzymes

Diethylhexyl phthalate exposure amplifies oxidant and inflammatory response in fetal hyperglycemia model predisposing insulin resistance in zebrafish embryos

Exposure of zebrafish embryos to glucose is a suitable model for the fetal hyperglycemia seen in gestational diabetes. Diethylhexyl phthalate (DEHP), which is considered an endocrine-disrupting chemical, is one of the most common phthalate derivatives used in stretching plastic and is encountered in every area where plastic is used in daily life. In the present study, the effects of DEHP on pathways related to insulin resistance and obesity were examined in zebrafish embryos exposed to glucose as a fetal hyperglycemia model. Zebrafish embryos were exposed to DEHP, glucose, and glucose + DEHP for 72 h post-fertilization (hpf), and developmental parameters and locomotor activities were monitored. At 72 hpf ins, lepa, pparγ, atf4a, and il-6 expressions were determined by RT-PCR. Glucose, lipid peroxidation (LPO), nitric oxide (NO) levels, glutathione S-transferase (GST), superoxide dismutase (SOD), and acetylcholine esterase (AChE) activities were measured spectrophotometrically. Compared with the control group, glucose, LPO, GST activity, il6, and atf4a expressions increased in all exposure groups, while body length, locomotor, and SOD activities decreased. While AChE activity decreased in the DEHP and glucose groups, it increased in the glucose + DEHP group. Although glucose exposure increased pparγ and lepa expressions, DEHP significantly decreased the expressions of pparγ and lepa both in the DEHP and glucose + DEHP groups. Our findings showed that DEHP amplified oxidant and inflammatory responses in this fetal hyperglycemia model, predisposing insulin resistance in zebrafish embryos.

Genetic interaction in the association between oxidative stress and diabetes in the Spanish population

Oxidative stress (OS) is a relevant intermediate mechanism involved in Type 2 Diabetes Mellitus (T2D) development. To date, the interaction between OS parameters and variations in genes related to T2D has not been analyzed.

AIMS

To study the genetic interaction of genes potentially related to OS levels (redox homeostasis, renin-angiotensin-aldosterone system, endoplasmic stress response, dyslipidemia, obesity and metal transport) and OS and T2D risk in a general population from Spain (the Hortega Study) in relation to the risk of suffering from T2D.

MATERIALS AND METHODS

One thousand five hundred and two adults from the University Hospital Rio Hortega area were studied and 900 single nucleotide polymorphisms (SNPs) from 272 candidate genes were analyzed.

RESULTS

There were no differences in OS levels between cases and controls. Some polymorphisms were associated with T2D and with OS levels. Significant interactions were observed between OS levels and two polymorphisms in relation to T2D presence: rs196904 (ERN1 gene) and rs2410718 (COX7C gene); and between OS levels and haplotypes of the genes: SP2, HFF1A, ILI8R1, EIF2AK2, TXNRD2, PPARA, NDUFS2 and ERN1.

CONCLUSIONS

Our results indicate that genetic variations of the studied genes are associated with OS levels and that their interaction with OS parameters may contribute to the risk of developing T2D in the Spanish general population. These data support the importance of analyzing the influence of OS levels and their interaction with genetic variations in order to establish their real impact in T2D risk. Further studies are required to identify the real relevance of interactions between genetic variations and OS levels and the mechanisms involved in them.

A Review of Fibraurea tinctoria and Its Component, Berberine, as an Antidiabetic and Antioxidant

Diabetes mellitus is a group of metabolic disorders characterized by hyperglycemia caused by resistance to insulin action, inadequate insulin secretion, or excessive glucagon production. Numerous studies have linked diabetes mellitus and oxidative stress. People with diabetes usually exhibit high oxidative stress due to persistent and chronic hyperglycemia, which impairs the activity of the antioxidant defense system and promotes the formation of free radicals. Recently, several studies have focused on exploring natural antioxidants to improve diabetes mellitus. Fibraurea tinctoria has long been known as the native Borneo used in traditional medicine to treat diabetes. Taxonomically, this plant is part of the Menispermaceae family, widely known for producing various alkaloids. Among them are protoberberine alkaloids such as berberine. Berberine is an isoquinoline alkaloid with many pharmacological activities. Berberine is receiving considerable interest because of its antidiabetic and antioxidant activities, which are based on many biochemical pathways. Therefore, this review explores the pharmacological effects of Fibraurea tinctoria and its active constituent, berberine, against oxidative stress and diabetes, emphasizing its mechanistic aspects. This review also summarizes the pharmacokinetics and toxicity of berberine and in silico studies of berberine in several diseases and its protein targets.

RDW as A Predictor for No-Reflow Phenomenon in DM Patients with ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

BACKGROUND

No-reflow phenomenon (NRP) in ST-segment elevation myocardial infarction (STEMI) patients is not infrequent. The predictive value of red blood-cell distribution width (RDW) on NRP has not been explored.

METHODS

STEMI patients undergoing primary percutaneous coronary intervention (pPCI) were enrolled. Plasma samples were obtained at admission. Participants were divided into two groups according to RDW. Logistic regression and receiver operating characteristic (ROC) curve were performed to evaluate the relationship between RDW and NRP. Subgroup analysis was made between the diabetes mellitus (DM) group and the No-DM group.

RESULTS

The high RDW group had a higher NRP compared to the low group. In multivariate logistic regression analysis, DM (adjusted odds ratio [AOR]:1.847; 95% confidence interval [CI]: 1.209-2.822; p = 0.005) and hemoglobin (AOR: 0.986; 95% CI: 0.973-0.999; p < 0.05), other than RDW, were independent predictors of NRP. RDW (AOR: 2.679; 95% CI: 1.542-4.655; p < 0.001) was an independent predictor of NRP in the DM group, but not in the No-DM group. In the DM group, area under the ROC curve value for RDW predicting NRP was 0.707 (77.3% sensitivity, 56.3% specificity (p < 0.001)).

CONCLUSIONS

RDW is a predictor of NRP in DM patients with STEMI, which provides further assistance in clinicians' decision making.

Antidiabetic and Liver Histological and Ultrastructural Effects of Cynara scolymus Leaf and Flower Head Hydroethanolic Extracts in Nicotinamide/Streptozotocin-Induced Diabetic Rats

This study aims to investigate the effect of hydroethanolic extracts of Cynara scolymus (C. scolymus) leaf (CLHE) and C. scolymus flower (CFHE) on the hepatic histopathological lesions and functional biochemical changes induced by type 2 diabetes mellitus (T2DM). The rat model of T2DM was induced by intraperitoneal injection of streptozotocin (STZ) in a dose of 60 mg/kg for 15 minutes following nicotinamide (NA) (60 mg/kg). The rats were allocated into four groups: group 1 (negative control), group 2 (diabetic control), group 3 (diabetic rats supplemented with 100 mg/kg/day CLHE), and group 4 (diabetic rats supplemented with 100 mg/kg/day CFHE). Treatment with CLHE and CFHE, for the study duration of 28 days, significantly improved the deteriorated hepatic glycogen content, glycogen phosphorylase, glucose-6-phosphatase activities, serum fructosamine levels, lipid profile, aspartate transaminase activities, and alanine transaminase activities as well as serum insulin and C-peptide levels. The elevated liver lipid peroxidation and the decreased activities of superoxide dismutase and glutathione peroxidase were significantly alleviated. The elevated expression of the proinflammatory cytokine tumor necrosis factor-α in the liver of diabetic rats was significantly reduced by treatments with CLHE and CFHE. NA/STZ-induced T2DM exhibited hepatic histopathological changes in the form of disordered hepatocytes, cytoplasm dissolution, and mononuclear leukocytic infiltration. The electron microscopic ultrastructure study revealed damaged mitochondria with ill-defined cristae and fragmentation of the rough endoplasmic reticulum. Treatments with CLHE and CFHE remarkably amended these histopathological and EM ultrastructural changes. In conclusion, both CLHE and CFHE may have antidiabetic and improvement effects on the liver function and structural integrity, which may be mediated, at least in part, via suppression of inflammation and oxidative stress and enhancement of the antioxidant defence system.

Duodenojejunal Omega Switch Surgery Reduces Oxidative Stress Induced by Cafeteria Diet in Sprague-Dawley Rats

Over-nutrition with cafeteria diet leads to glycemic control failure and subsequent obesity. Bariatric surgery remains the ultimate treatment option, and when complemented with specific dietary protocol, it may mitigate the effects of oxidative stress induced by a cafeteria diet. The study measured antioxidant marker activity: superoxidase dismutase (SOD) and ceruloplasmin (CER), total antioxidant capacity (TAC), and lipid peroxidation marker concentrations: lipofuscin (LS) and malondialdehyde (MDA), in the plasma of 56 Sprague-Dawley rats fed with a cafeteria (HFS) or a control (CD) diet and subjected to duodenojejunal omega switch (DJOS) or control (SHAM) surgery. The diet change after the surgery (CD/HFS or HFS/CD) strongly influenced SOD activity in DJOS- and SHAM-operated rats, but SOD activity was always higher in SHAM-operated rats. Every dietary protocol used in the study increased CER activity, except for the CD/CD combination. Cafeteria diet consumed before or after either of surgeries led to decrease in TAC levels. DJOS and no change in diet reduced MDA levels. DJOS reduced LS levels, but its beneficial effect was deteriorated by selected dietary protocols. The cafeteria diet negatively affected the positive impact of DJOS surgery, but SOD, CER, MDA, and LS were significantly lower in rats that underwent DJOS, suggesting that eight weeks of dietary treatment before and after the surgery did not totally dilapidate the effects of the bariatric treatment.

Mechanisms of Kaempferol in the treatment of diabetes: A comprehensive and latest review

Obesity-insulin resistance-β-cells apoptosis" is an important trilogy of the pathogenesis of type 2 diabetes. With the global pandemic of obesity and diabetes, continuous research and development of new drugs focuses on the prevention of the pathological progress of these diseases. According to a recent study, the natural product kaempferol has excellent antidiabetic effects. Therefore, this review comprehensively summarized the frontier studies and pharmacological mechanisms of kaempferol in the treatment of diabetes. The successful research and development of kaempferol may yield a significant leap in the treatment of diabetes and its complications.

Effect of Adhatoda zeylanica Ethanolic Extract on Attenuated Kidney in Streptozotocin-Induced Diabetic Rats

Objective The present study was aimed to evaluate the effect of ethanolic extract of Adhatoda zeylanica (EAZ) leaves on streptozotocin (STZ)-induced diabetes mellitus (DM) and its renal complications in male Wistar albino rats.

Materials and Methods Adult male Wistar albino rats were randomly selected from a colony, divided into four groups, namely, A, B, C, and D, with each having six rats (n = 6) and each weighing between 200 and 250 g. Group A served as control and received only water per oral (p.o.). Group B, C, and D animals received a single dose of STZ at 45 mg/kg body weight (kbw) intraperitoneal administration (i.p.) on day 1 and observed for fasting blood glucose (FBG) to induce DM for next 72 hours. After the DM was induced, group B served as DM control, group C received the standard drug glibenclamide (GL) at 5 mg/kbw p.o. once daily, and group D received EAZ of 500 mg/kbw p.o. once daily for 35 days. After the observation period, the animals were euthanized, serum creatinine and blood urea, antioxidants in the kidney tissue homogenate, and histopathological studies were assessed to know the ameliorative effect of the test drugs.

Results Renal parameters, such as serum creatinine, blood urea, antioxidants activities, in group D were nearer to the control when compared with groups B and C. Histopathological studies revealed that there was minimal renal damage in group D when compared with groups B and C.

Conclusion Administration of ethanolic EAZ showed significant ameliorative effects on the FBG, biochemical, oxidative, and histopathological parameters on kidney tissues treated with STZ to induce DM.

Antioxidant Effects of Trehalose in an Experimental Model of Type 2 Diabetes

BACKGROUND

Oxidative stress that occurs as a consequence of the imbalance between antioxidant activity and free radicals can contribute in the pathogenesis of metabolic disorders, such as type 2 diabetes mellitus (T2DM). Antioxidant therapies have been proposed as possible approaches to treat and attenuate diabetic complications. The purpose of this study was to evaluate potential antioxidant effects of trehalose on oxidative indices in a streptozotocin (STZ)-induced diabetic rat model.

METHODS

Diabetic rats were divided randomly into five treatment groups (six rats per group). One test group received 45 mg/kg/day trehalose via intraperitoneal injection, and another received 1.5 mg/kg/day trehalose via oral gavage for 4 weeks. Three control groups were also tested including nondiabetic rats as a normal control (NC), a nontreated diabetic control (DC), and a positive control given 200 mg/kg/day metformin. Levels of thiol groups (-SH), and serum total antioxidant capacity were measured between control and test groups. In addition, superoxide dismutase (SOD) and glutathione peroxidase (GPx) enzyme activities were assessed.

RESULTS

In both oral and injection trehalose-treated groups, a marked increase was observed in serum total antioxidant capacity (TAC) (p > 0.05) and thiol groups (-SH) (p < 0.05). Also, SOD and GPx activities were increased after 4 weeks of treatment with trehalose.

CONCLUSION

In conclusion, the present results indicate ameliorative effects of trehalose on oxidative stress, with increase antioxidant enzyme activities in STZ-induced diabetic rats.

Oxidative stress and diabetes: antioxidative strategies

Diabetes mellitus is one of the major public health problems worldwide. Considerable recent evidence suggests that the cellular reduction-oxidation (redox) imbalance leads to oxidative stress and subsequent occurrence and development of diabetes and related complications by regulating certain signaling pathways involved in β-cell dysfunction and insulin resistance. Reactive oxide species (ROS) can also directly oxidize certain proteins (defined as redox modification) involved in the diabetes process. There are a number of potential problems in the clinical application of antioxidant therapies including poor solubility, storage instability and nonselectivity of antioxidants. Novel antioxidant delivery systems may overcome pharmacokinetic and stability problem and improve the selectivity of scavenging ROS. We have therefore focused on the role of oxidative stress and antioxidative therapies in the pathogenesis of diabetes mellitus. Precise therapeutic interventions against ROS and downstream targets are now possible and provide important new insights into the treatment of diabetes.

Poor Glycaemic Control Is Associated with Increased Lipid Peroxidation and Glutathione Peroxidase Activity in Type 2 Diabetes Patients

Glycaemic control is the main focus of managing diabetes and its complications. Hyperglycaemia induces oxidative stress favouring cellular damage and subsequent diabetic complications. The present study was conducted to compare the plasma total antioxidant capacity (TAC) and individual antioxidant marker antioxidant status of type 2 diabetics (T2D) with good ((+) GC) and poor ((-) GC) glycaemic control with prediabetic (PDM) and normoglycaemic (NG) individuals. T2D (n = 147), PDM (n = 47), and NGC (n = 106) were recruited as subjects. T2D and PDM had lower plasma TAG than NG subjects. T2D and PDM had significantly higher GPx activity and plasma MDA concentrations than NG. PDM showed the highest SOD activity. T2D (-) GC showed significantly elevated GPx activity and higher MDA level and significantly lower SOD activity among all study groups. Lower plasma TAC and higher plasma MDA indicate the presence of oxidative stress in T2D and PDM. Elevated GPx activity in T2D, PDM, and particularly in T2D (-) GC suggests a compensatory response to counteract excess lipid peroxidation in the hyperglycaemic state. Decline in SOD activity advocates the presence of glycation and excess lipid peroxidation in T2D.

Action of corilagin on hyperglycemia, hyperlipidemia and oxidative stress in streptozotocin-induced diabetic rats

Diabetes mellitus is the world's most common endocrine disease involving metabolic disorders of carbohydrate, protein and fat. This study was undertaken to investigate the anti-diabetic activity of corilagin, a member of polyphenolic tannins used against hyperglycemia and many other diseases in well-known animal models. Diabetes was induced chemically by intraperitoneal administration of Streptozotocin (40 mg/kg bw) to albino Wistar rats. Diabetic rats showed significant increase in the levels of fasting blood glucose, glycated haemoglobin, total cholesterol, triglyceride, low density lipoprotein cholesterol, very low density lipoprotein cholesterol, and a significant decrease in the level of body weight, plasma insulin, high density lipoprotein cholesterol, antioxidant activities, viz. superoxide dismutase, catalase and reduced glutathione when compared to controls. However, after 30 days of oral administration of corilagin (10 and 20 mg/kg bw/day) to these diabetic rats evoked significant alterations in the above mentioned parameters. The effect of corilagin was compared with the standard drug, glibenclamide (0.1 mg/kg body weight/day). Thus, the present study suggests that the corilagin acts as a natural, effective therapeutic agent to regulate diabetes, by exhibiting antidiabetic, antihyperlipidemic and antioxidant properties in STZ induced diabetic rats.

Effect of redox status of peripheral blood on immune signature of circulating regulatory and cytotoxic T cells in streptozotocin induced rodent model of type I diabetes

Diabetes mellitus is an autoimmune chronic inflammatory disease manifested by hyperglycemia and associated with imbalance in redox status and inflammatory response. Oxidative stress has been reported to affect functions of T cell repertoire- regulatory T cells (T_regs) and cytotoxic lymphocytes (CTLs). T_regs are involved in prevention against autoreactive T cells and controlling inflammation while CTLs are major mediators of tissue injury. Hence the present study is novel as it contemplates to understand oxidative stress in diabetes vis-à-vis T cells. Comparative analysis was carried out between two groups, i.e., healthy Sprague Dawley (SD) and Streptozotocin (STZ) induced SD rat model of type1 diabetes (T1D). Various hematological, biochemical and oxidative stress parameters were assessed in plasma samples in the study. Peripheral blood mononuclear cells (PBMCs), T_regs and CTLs were evaluated for intracellular oxidative stress using 2',7'-dichlorofluorescin diacetate (DCFDA), mitochondrial ROS using Mitosox-red, mitochondrial membrane potential using JC-1 in PBMCs. T_reg populations expressing IL-4, IL-6 and IL-10 and CTLs expressing αβ-T cell receptor (αβ -TCR), interferon- γ (IFN-γ), perforin and granzyme were also considered. We found decreased activity of enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and reduced glutathione(GSH) and increased lipid peroxidation (LPO) in plasma indicated altered redox state in diabetic animals. Elevated intracellular reactive oxygen species (ROS) and mitochondrial superoxide was observed in T1D group confirming oxidative stress in cell specific manner. Cell population with hyperpolarized mitochondrial membrane potential was found to be elevated in T1D group. We found a decrease in T_reg population in T1D group in comparison to healthy group. T_reg population expressing IL-4, IL-6 were increased and those expressing IL-10 were found to be reduced in diabetic group. The CTL numbers were dropping whereas αβ-TCR, IFN-γ, perforin and granzyme expressing CTLs were on the rise in diabetic group. Our finding suggested an increased oxidative stress in T_regs and CTLs which might be responsible for progressive inflammatory environment built up due to persistent hyperglycemia. This was fortified by the statistical analyses where strong correlation between LPO and CTLs expressing TCR, IFN-γ, perforin and granzyme was noted. Lipid peroxidation was also found to be correlated to intracellular ROS in T_regs and CTLs along with other important revelations. The present study gives important insights into the significance of oxidative stress on immune system and its mediators in diabetes.

Erythrocytes as Potential Link between Diabetes and Alzheimer's Disease

Many studies support the existence of an association between type 2 diabetes (T2DM) and Alzheimer's disease (AD). In AD, in addition to brain, a number of peripheral tissues and cells are affected, including red blood cell (RBC) and because there are currently no reliable diagnostic biomarkers of AD in the blood, a gradually increasing attention has been given to the study of RBC's alterations. Recently it has been evidenced in diabetes, RBC alterations superimposable to the ones occurring in AD RBC. Furthermore, growing evidence suggests that oxidative stress plays a pivotal role in the development of RBC's alterations and vice versa. Once again this represents a further evidence of a shared pathway between AD and T2DM. The present review summarizes the two disorders, highlighting the role of RBC in the postulated common biochemical links, and suggests RBC as a possible target for clinical trials.

Effects of Melatonin on Oxidative Stress in Streptozotocin-Induced Diabetic Rats

Oxidative stress plays an important role in diabetes and other oxygen-related diseases. Melatonin, a pineal hormone thought to be a scavenger of oxygen radicals and a potentially advantageous therapeutic agent in diseases having oxidative stress, was administered (10 mg/kg ip, in gum tragacanth to prolong its absorption, once a day for 4 successive days) to normal and 30-day streptozotocin-induced diabetic Sprague-Dawley rats, after which markers of oxidative stress were assessed in the liver, kidney, intestine, and spleen. Alanine and aspartate aminotransferase activities in serum, which were increased after diabetes, were not increased further by melatonin administration, indicating that there was no melatonin-related liver toxicity. Most melatonin-induced effects were seen in the liver, and very few in extrahepatic tissues. In livers of diabetic rats, reduced concentration of nitrite and increased lipid peroxidation were both restored to normal levels following treatment with melatonin. Hepatic glutathione peroxidase activity was not changed in diabetics, but was decreased after melatonin administration in both normal and diabetic animals. Total glutathione concentrations were significantly decreased in livers of all diabetics and were not normalized by melatonin treatment. Hepatic superoxide dis-mutase activity was elevated following melatonin dosing in normal rats, but dropped below normal levels in diabetic rats and was not restored by melatonin treatment. Glutathione 5-transferase activity was higher than normal in melatonin-dosed normal rat livers. These results suggest that after 4 days of administration, melatonin may enable various enzymes of the hepatic antioxidative defense system to better detoxify harmful oxygen radicals without producing overt toxicity in a disease such as diabetes.

The cardioprotective power of leaves

Lack of physical activity, smoking and/or inappropriate diet can contribute to the increase of oxidative stress, in turn affecting the pathophysiology of cardiovascular diseases. Strong anti-oxidant properties of plant polyphenolic compounds might underlie their cardioprotective activity. This paper reviews recent findings on the anti-oxidant activity of plant leaf extracts and emphasizes their effects on blood platelets, leukocytes and endothelial cells - the targets orchestrating the development and progression of cardiovascular diseases. We also review the evidence linking supplementation with plant leaf extracts and the risk factors defining the metabolic syndrome. The data point to the importance of leaves as an alternative source of polyphenolic compounds in the human diet and their role in the prevention of cardiovascular diseases.

Hepatoprotective effects of selenium during diabetes in rats

The present study investigated the hepatoprotective role of selenium during alloxan-induced diabetes in rats. Male Wistar rats were divided into four groups, namely, normal control, selenium treated, diabetic, and selenium-treated diabetic. Diabetes was induced in the animals by injecting alloxan intraperitoneally at a dose rate of 150 mg/kg body weight. Selenium in the form of sodium selenite was supplemented to rats at a dose level of 1 ppm in drinking water, ad libitum for two time durations of 2 and 4 weeks. The effects of different treatments were studied on various parameters in rat liver, which included serum glucose levels, serum insulin levels, alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lipid peroxidation (LPO), glutathione reduced (GSH), oxidized glutathione (GSSG), total glutathione (TG), superoxide dismutase (SOD), catalase (CAT), glutathione reductase, glutathione peroxidase, metallothionein (MT), and histoarchitecture. A significant increase in the serum glucose levels, LPO levels, and in enzyme activities of ALP, ALT, and AST was observed in diabetic rats which, however, got decreased significantly upon supplementation with selenium. On the contrary, decreased enzyme activities of GSSG, SOD, and CAT and depressed levels of GSH as well as serum insulin levels were observed in diabetic rats which got improved following selenium supplementation. Interestingly, MT levels were increased both in diabetic and selenium-treated diabetic rats. Further, marked alterations in histoarchitecture were seen in diabetic rats with the prominent features being congestion in sinusoids, lipid accumulation, and centrilobular hepatocyte degeneration. However, selenium treatment to diabetic rats showed overall improvement in the hepatic histoarchitecture.

Ameliorative effect of vanadium on oxidative stress in stomach tissue of diabetic rats

Between their broad spectrum of action, vanadium compounds are shown to have insulin mimetic/enhancing effects. Increasing evidence in experimental and clinical studies suggests that oxidative stress plays a major role in the pathogenesis of diabetes and on the onset of diabetic complications. Thus, preventive therapy can alleviate the possible side effects of the disease. The aim of the present study was to investigate the effect of vanadyl sulfate supplementation on the antioxidant system in the stomach tissue of diabetic rats. Male Swiss albino rats were randomly divided into 4 groups: control; control+vanadyl sulfate; diabetic; diabetic+vanadyl sulfate. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ; 65 mg/kg body weight). Vanadyl sulfate (100 mg/kg body weight) was given daily by gavage for 60 days. At the last day of the experiment, stomach tissues were taken and homogenized to make a 10% (w/v) homogenate. Catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST), myeloperoxidase (MPO), carbonic anhydrase (CA), glucose-6-phosphate dehydrogenase (G6PD) and lactate dehydrogenase (LDH) activities were determined in the stomach tissue. CAT, SOD, GR, GPx, GST, CA, G6PD and LDH activities were increased in diabetic rats when compared to normal rats. Vanadium treatment significantly reduced the elevated activities of GR, GPx, GST compared with the diabetic group whereas the decreases in CAT, SOD, CA, G6PD and LDH activities were insignificant. No significant change was seen for MPO activity between the groups. It was concluded that vanadium could be used for its ameliorative effect against oxidative stress in diabetes.

Heme oxygenase-1: an emerging therapeutic target to curb cardiac pathology

Activation of heme oxygenase-1 (HO-1), a heme-degrading enzyme responsive to a wide range of cellular stress, is traditionally considered to convey adaptive responses to oxidative stress, inflammation and vasoconstriction. These diversified effects are achieved through the degradation of heme to carbon monoxide (CO), biliverdin (which is rapidly converted to bilirubin by biliverdin reductase) and ferric iron. Recent findings have added antiproliferative and angiogenic effects to the list of HO-1/CO actions. HO-1 along with its reaction products bilirubin and CO are protective against ischemia-induced injury (myocardial infarction, ischemia-reperfusion (IR)-injury and post-infarct structural remodelling). Moreover, HO-1, and CO in particular, possess acute antihypertensive effects. As opposed to these curative potentials, the long-believed protective effect of HO-1 in cardiac remodelling in response to pressure overload and type 2 diabetes mellitus (DM) has been questioned by recent work. These challenges, coupled with emerging regulatory mechanisms, motivate further in-depth studies to help understand untapped layers of HO-1 regulation and action. The outcomes of these efforts may shed new light on critical mechanisms that could be used to harness the protective potential of this enzyme for the therapeutic benefit of patients suffering from such highly prevalent cardiovascular disorders.

Curcumin regulates gene expression of insulin like growth factor, B-cell CLL/lymphoma 2 and antioxidant enzymes in streptozotocin induced diabetic rats

Background

The effects of curcumin on the activities and gene expression of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (G-ST), B-cell CLL/lymphoma 2 (Bcl-2) and insulin like growth factor-1 (IGF-1) in diabetic rats were studied.

Methods

Twenty four rats were assigned to three groups (8 rats for each). Rats of first group were non diabetic and rats of the second group were rendered diabetic by streptozotocin (STZ). Both groups received vehicle, corn oil only (5 ml/kg body weight) and served as negative and positive controls, respectively. Rats of the third group were rendered diabetic and received oral curcumin dissolved in corn oil at a dose of 15 mg/5 ml/kg body weight for 6 weeks.

Results

Diabetic rats showed significant increase of blood glucose, thiobarbituric acid reactive substances (TBARS) and activities of all antioxidant enzymes with significant reduction of reduced glutathione (GSH) compare to the control non diabetic group. Gene expression of Bcl2, SOD, CAT, GPX and GST was increased significantly in diabetic untreated rats compare to the control non diabetic group. The administration of curcumin to diabetic rats normalized significantly their blood sugar level and TBARS values and increased the activities of all antioxidant enzymes and GSH concentration. In addition, curcumin treated rats showed significant increase in gene expression of IGF-1, Bcl2, SOD and GST compare to non diabetic and diabetic untreated rats.

Conclusion

Curcumin was antidiabetic therapy, induced hypoglycemia by up-regulation of IGF-1 gene and ameliorate the diabetes induced oxidative stress via increasing the availability of GSH, increasing the activities and gene expression of antioxidant enzymes and Bcl2. Further studies are required to investigate the actual mechanism of action of curcumin regarding the up regulation of gene expression of examined parameters.

Acute blood glucose fluctuations can decrease blood glutathione and adiponectin levels in patients with type 2 diabetes

INTRODUCTION

Glutathione appears to have apparent antioxidant activity to counter regulate hyperglycemia induced oxidative stress. Adiponectin also plays a role in the suppression of the metabolic derangements in type 2 diabetes mellitus (DM). The aim of this study was to determine whether blood glucose fluctuations can alter blood levels of glutathione and adiponectin.

METHODS

We enrolled 34 patients with type 2 DM. As a measure of short-term glycemic variability, the mean amplitude of glycemic excursions (MAGE) was computed from a continuous glucose monitor system (CGMS), and data were recorded over 72 h. For long-term glycemic variability, we calculated the standard deviation (SD) of HbA1c over a 2-year period. Glutathione and adiponectin levels were measured after completing the 72-h CGMS data collection.

RESULTS

The blood levels of glutathione were significantly and negatively correlated with MAGE (r = -0.543; P < 0.001), but not with HbA1c and SD of HbA1c. Adiponectin levels were also significantly and negatively correlated with MAGE and SD of HbA1c (r = -0.64 and r = -0.55, respectively; P < 0.001). Using generalized estimating equations, multivariate regression analysis revealed that MAGE is an independent predictor of serum levels of adiponectin (P = 0.002) and glutathione (P = 0.004).

CONCLUSIONS

We found strong associations between acute blood glucose variability, glutathione, and adiponectin in type 2 diabetic patients treated with oral hypoglycemic agent therapy.

Oxidative stress is the primary event: Effects of ethanol consumption in brain

Damaging effects of reactive oxygen species on living systems are well documented. They include oxidative attack on vital cell constituents. Chronic ethanol administration is able to induce an oxidative stress in the central nervous system. In the present study, 16-18 week-old male albino rats of Wistar strain were exposed to different concentration of ethanol for 4 weeks. This exposure showed profound effect on body weight. Ascorbic acid level; and activities of alkaline phosphatase and aspartate transaminase in the brain are dependent on the concentration of ethanol exposure. Chronic ethanol ingestion elicits statistically significant increase in thiobarbituric acid reactive substances level and decrease in gluatathione level in the brain. It reduces superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities in a dose dependent manner. However, histological examination could not reveal any pathophysiological changes. Therefore, we conclude that biochemical alterations and oxidative stress related parameters respond early in alcoholism than the histopathological changes in brain.

Effect of potent ethyl acetate fraction of Stereospermum suaveolens extract in streptozotocin-induced diabetic rats

To evaluate the antihyperglycemic effect of ethyl acetate fraction of ethanol extract of Stereospermum suaveolens in streptozotocin-(STZ-) induced diabetic rats by acute and subacute models. In this paper, various fractions of ethanol extract of Stereospermum suaveolens were prepared and their effects on blood glucose levels in STZ-induced diabetic rats were studied after a single oral administration (200 mg/kg). Administration of the ethyl acetate fraction at 200 mg/kg once daily for 14 days to STZ-induced diabetic rats was also carried out. The parameters such as the fasting blood glucose, hepatic glycogen content, and pancreatic antioxidant levels were monitored. In the acute study, the ethyl acetate fraction is the most potent in reducing the fasting serum glucose levels of the STZ-induced diabetic rats. The 14-day repeated oral administration of the ethyl acetate fraction significantly reduced the fasting blood glucose and pancreatic TBARS level and significantly increased the liver glycogen, pancreatic superoxide dismutase, and catalase activities as well as reduced glutathione levels. The histopathological studies during the subacute treatment have been shown to ameliorate the STZ-induced histological damage of pancreas. This paper concludes that the ethyl acetate fraction from ethanol extract of Stereospermum suaveolens possesses potent antihyperglycemic and antioxidant properties, thereby substantiating the use of plant in the indigenous system of medicine.

Antidiabetic and antioxidant effect of Semecarpus anacardium Linn. nut milk extract in a high-fat diet STZ-induced type 2 diabetic rat model

Semecarpus anacardium commonly known as marking nut has been used in the Siddha system of medicine against various ailments. The antidiabetic and antioxidant potential of the drug was evaluated in Type 2 diabetic rats induced by feeding a high-fat diet (HFD) for 2 weeks followed by single intraperitoneal injection of streptozotocin (STZ) 35 mg/kg body weight. Three days after STZ induction, the hyperglycemic rats were treated with Semecarpus anacardium nut milk extract (SA) orally at a dosage of 200 mg/kg body weight daily for 30 days. Metformin (500 mg/kg body weight, orally) was used as a reference drug. The fasting blood glucose, insulin, Hb, HbA1c levels, and HOMA-IR and HOMA-β were measured, and also the levels of lipid peroxidation and antioxidant enzymes were observed. SA significantly (p < .05) reduced and normalized blood glucose levels and also decreased the levels of HbA1c as compared with that of HFD STZ control group. SA treatment also significantly (p < .05) increased the levels of antioxidant enzymes while decreasing the levels of lipid peroxidation. The potential antihyperglycemic action and antioxidant role might be due to the presence of flavonoids in the drug.

Evaluation of glycemic and oxidative/antioxidative status in the estradiol valerate-induced PCOS model of rats

OBJECTIVE

The aim of this study was to show glycemic and oxidative/antioxidative status (GOAS) in rats with estradiol valerate (EV)-induced polycystic ovarian syndrome.

STUDY DESIGN

Thirty mature female rats were randomly allocated to EV-induced PCOS, sham and control groups. Malondialdehyde, catalase and fasting blood glucose levels were determined in order to evaluate GOAS.

RESULTS

There was a statistically significant difference between PCOS and control groups (p<0.001) for hemolysate MDA while no difference was determined for either catalase or fasting blood glucose levels. On histopathological examination, the EV-induced PCOS group revealed disease-characteristic ovarian morphology.

CONCLUSION

There was an increased compensation for oxidative stress by antioxidative biologic mechanisms in EV-induced PCOS rats. Interestingly, the sole result derived from this limited study is that the sesame oil+EV combination is not appropriate for the evaluation of oxidant-antioxidant status and also glycemic condition in PCOS. This study demonstrates the need for better designed experimental studies to elucidate the aetiopathogenesis of PCOS via novel techniques.

Influence of vanadium supplementation on oxidative stress factors in the muscle of STZ-diabetic rats

In recent years, the role of free radical damage consequent to oxidative stress is widely discussed in diabetic complications. In this aspect, the protection of cell integrity by trace elements is a topic to be investigated. Vanadium is a trace element believed to be important for normal cell function and development. The aim of the present study was to investigate the effect of vanadyl sulfate supplementation on the antioxidant system in the muscle tissue of diabetic rats. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg body weight) to male Swiss albino rats. The rats were randomly divided into 4 groups: Group I, control; Group II, vanadyl sulfate control; Group III, STZ-diabetic untreated; Group IV, STZ-diabetic treated with vanadyl sulfate. Vanadyl sulfate (100 mg/kg) was given daily by gavage for 60 days. At the last day of the experiment, rats were killed, muscle tissues were taken, homogenized in cold saline to make a 10% (w/v) homogenate. Body weights and blood glucose levels were estimated at 0, 30 and 60th days. Antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST), as well as carbonic anhydrase (CA), myeloperoxidase (MPO) activities and protein carbonyl content (PCC) were determined in muscle tissue. Vanadyl sulfate administration improved the loss in body weight due to STZ-induced diabetes and decreased the rise in blood glucose levels. It was shown that vanadium supplementation to diabetic rats significantly decrease serum antioxidant enzyme levels, which were significantly raised by diabetes in muscle tissue showing that this trace element could be used as preventive for diabetic complications.

WITHDRAWN: Proteome and phytochemical analysis of Cynodon dactylon leaves extract and its biological activity in diabetic rats

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.bionut.2010.09.001. The duplicate article has therefore been withdrawn.

Effects of Xylopia aethiopica (Annonaceae) fruit methanol extract on gamma-radiation-induced oxidative stress in brain of adult male Wistar rats

Xylopia aethiopica (XA) (Annonaceae) possesses great nutritional and medicinal values. This study was designed to investigate the effects of XA fruit methanol extract on oxidative stress in brain of rats exposed to whole body gamma-radiation (5 Gy). Vitamin C (VC) served as standard antioxidant. Forty-four rats were divided into 4 groups of 11 rats each. One group served as control, two different groups were treated with XA and VC (250 mg/kg), 6 weeks before and 8 weeks after irradiation, and fourth group was only irradiated. Rats were sacrificed 1 and 8 weeks after irradiation. The antioxidant status, viz. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) and glutathione (GSH) were estimated. Results indicate a significant increase (p < 0.05) in levels of brain LPO after irradiation. LPO increased by 90% and 151%, after 1 and 8 weeks of irradiation, respectively. Irradiation caused significant (p < 0.05) decreases in levels of GSH and GST by 61% and 43% after 1 week and, 75% and 73%, respectively, after 8 weeks of exposure. CAT and SOD levels were decreased by 62% and 68%, respectively, after 8 weeks of irradiation. Treatment with XA and VC ameliorated the radiation-induced decreases in antioxidant status of the animals. These suggest that XA could have beneficial effect by inhibiting oxidative damage in brain of exposed rats.

Role of oxidative stress in hearing impairment in patients with type two diabetes mellitus

OBJECTIVE

Although many clinical investigations have found a relationship between hearing loss and diabetes mellitus, the pathophysiology of this effect remains controversial. To date, the mechanisms of hearing loss in diabetic patients have been explained in terms of microangiopathy, neuropathy and encephalopathy. However, many reports indicate that some diabetic complications are associated with oxidative stress related to the diabetes itself. In the present study, we hypothesised that oxidative stress may be a cause of hearing loss in diabetic patients.

METHODS

The study group comprised non-insulin dependent diabetic patients with no signs of microangiopathy or peripheral neuropathy. The control group comprised sex-, age- and body weight matched, non-diabetic subjects. Auditory function was evaluated using pure tone audiometry and tympanometry. Subjects with normal hearing and sensorineural hearing loss were included in the study, whereas subjects with conductive hearing loss were excluded. Both the study group (n = 63) and the control group (n = 37) were divided into subgroups based on the presence and absence of hearing loss. Oxidative stress was evaluated by measuring serum indicators of protein oxidation and lipid peroxidation, serum levels of nitric oxide and various non-enzymatic antioxidants, and the activity of various enzymatic antioxidants.

RESULTS

The non-insulin dependent diabetic patients had significantly higher serum levels of protein oxidation products, nitric oxide, enzymatic antioxidant activity (i.e. glutathione peroxidase and superoxide dismutase), compared with the control group (p < 0.05). When we compared the groups in relation to the presence of hearing loss, the nitric oxide level was significantly increased in the diabetic group with good hearing, compared with diabetic patients with hearing loss (p = 0.014). In the diabetic group, a clear, negative correlation was observed between serum levels of nitric oxide and vitamins C and E, and hearing impairment (r = -0.395, r = -0.318, r = -0.500, respectively). There was also a positive correlation between serum vitamin C concentrations and hearing levels in the control group (r = 0.417).

CONCLUSION

These results suggest that oxidative stress may play an important role in hearing impairment in diabetic patients. In this process, increased protein oxidation appears to be more important than lipid peroxidation. Nitric oxide may have a protective effect on hearing, as may some nonenzymatic antioxidants such as vitamin C and E.

Clinical evaluation of oxidative stress in patients with diabetes mellitus type II: Impact of acute exercise

Background/Aim. Exercise is a well recognized model of oxidative stress and, also, an important tool in diabetes management. The aim of our study was to evaluate oxidative stress in patients with diabetes mellitus type 2 and to determine influence of acute exercise training on the investigated parameters. Methods. To evaluate oxidative stress in the patients, we determinated following parameters: triglycerides (TG), total cholesterol, low density lipoprotein cholesterol (LDL), oxidized LDL cholesterol (Ox LDL), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), plasminogen activator inhibitor (PAI) which were measured at rest and immediately after the acute bout of cardiopulmonary exercise cycle-ergometer test. Results. In basal condition, diabetic patients compared to controls have significant higher values of TG (3.12 ? 1.09 vs 1.74 ? 0.9 mmol/L, p < 0.01), Ox LDL (84.73 ? 16.90 vs 79.00 ? 29.26 mmol/L, p < 0.05) and SOD enzyme activity (913.38 ? 120.36 vs 877.14 ? 153.18 U/g Hb, p < 0.05). During the acute exercise test, there was significant increase of Ox LDL in both the study patients (from 84.73 ? 16.90 to 92.33 ? 23.29 mmol/L, p < 0.05) and in the control group (from 79.00 ? 29.26 to 89.30 ? 29.07 mmol/L, p < 0.05). SOD activity was significantly increased in both groups during exercise, in diabetic patients from 913.38 ? 120.36 to 921.50 ? 130.03 U/gHb, p < 0.05, and in the controls from 877.14 ? 153.18 to 895.00 ? 193.49, U/gHb, p < 0.05. GSH-Px activity was significantly increased only in the diabetic patients after the acute exercise (from 45.04 ? 11.19 to 51.81 ? 15.07 U/gHb, p < 0.01), but not in the controls (from 44.63 ? 13.73 to 43.97 ? 25.97 U/gHb, p = ns). PAI significantly decreased during the exercise test, only in the healthy subjects (from 2.60 ? 0.35 to 2.22 ? 0.65, p < 0.05). Type 2 diabetic patients with complications had only significant increase in GSH-Px activity (from 47.10 ? 7.37 to 54.52 ? 11.97 U/gHb, p < 0.01). Conclusion. Elevated Ox LDL, SOD and GSH-Px levels are associated with acute exercise in type 2 diabetic patients. We suggest that it could be a compensatory mechanism to preventing free radicals tissue damage. We hypothesize that a physical training program induces an enhance of muscular and liver antioxidant enzymes activity and reduces oxidative stress. Further studies are needed to explore the relationship between exercise and antioxidant system in diabetic patients with and without complications.

Altered heat stress response following streptozotocin-induced diabetes

The heat shock response involves activation of heat shock transcription factor 1 (Hsf1) followed by the rapid synthesis of the protective heat shock proteins (Hsps). To determine if the stress experienced during streptozotocin (STZ)-induced diabetes altered the heat shock response, male Sprague-Dawley rats (n = 33; 280-300 g) were assigned to 4 groups: (1) control, (2) diabetic (30 days after 55 mg/kg STZ i.v.), (3) heat stressed (42 degrees C for 15 minutes), and (4) diabetic heat-stressed group (heat stressed 42 degrees C for 15 minutes, 30 days after 55 mg/kg STZ i.v.). The content of Hsp72, Hsp25, and Hsf1 in skeletal muscles, heart, kidney, and liver was assessed by Western blotting, while electrophoretic mobility shift gel analysis was used to assess Hsf activation. Without heat stress, the constitutive expression of Hsp25, Hsp72, and Hsf1 in tissues from diabetic animals and controls was similar. However, 24 hours following heat stress, the heart, kidney, and liver from diabetic animals showed an increased Hsp72 and Hsp25 content compared to the same tissues from heat-stressed nondiabetic animals (P < 0.05). The white gastrocnemius and plantaris muscles from heat-stressed animals (diabetic and nondiabetic) both showed significant and similar elevations in Hsp72 content. Interestingly, while all muscles from nondiabetic animals showed significant (P < 0.05) increase in Hsp25 content after heat stress, no increase in Hsp25 content was detected in muscles from heat-stressed diabetic animals. As expected, Hsf activation was undetectable in all tissues from non-heat-stressed animals but was detectable in tissues from both diabetic and nondiabetic animals following heat stress with the exception of diabetic skeletal muscle, where it was attenuated. Hsf1 content was unaltered in all tissues examined except in the white gastrocnemius muscles from heat-stressed diabetic animals, where it was undetectable. These results suggest that when tissues from STZ-induced diabetic animals are heat stressed, the Hsp/stress response is altered in a tissue-specific manner. This impaired ability to activate the stress response may explain, at least in part, the selective atrophy of certain muscles or muscle fiber types during diabetes.

Interrelationship of antioxidative status, lipid peroxidation, and lipid profile in insulin-dependent and non-insulin-dependent diabetic patients

This study aimed to investigate the interrelationship of plasma lipid profile, lipid peroxidation, and erythrocyte antioxidative defense in patients with insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus. Plasma levels of total cholesterol, triglycerides, and lipid peroxides and the activities of copper, zinc superoxide dismutase (CuZnSOD), catalase, glutathione peroxidase (GSH-Px), as well as the amount of glutathione in erythrocytes, were determined in IDDM, NIDDM, and nondiabetic control subjects. Additionally, morphology of erythrocytes in all subjects was examined. Plasma levels of total cholesterol and triglycerides were significantly increased in NIDDM compared with controls. Also, the lipid peroxide level was higher in NIDDM than in either control or IDDM subjects. CuZnSOD activity in erythrocytes was elevated in NIDDM patients compared with the control. In NIDDM patients, more extensive erythrocyte spherocytosis and echinocytosis compared with both control and IDDM subjects were observed. In contrast with the IDDM group, the observed abnormality in lipid metabolism in NIDDM patients is closely associated with increased lipid peroxidation, changes in antioxidative defense, and erythrocyte morphology.

Evaluation of selected parameters of the antioxidative system in patients with type 2 diabetes in different periods of metabolic compensation

Introduction:

The aim of the study was to evaluate some selected parameters of the antioxidative system in patients with type 2 diabetes.

Materials and Methods:

Eighty-one type 2 diabetes patients took part in the study (39 patients with metabolically balanced and 42 with metabolically unbalanced diabetes). The control group consisted of 30 healthy people. The total antioxidant capacity of plasma was measured fluorometrically using phycoerythrin. To calculate the low-molecular-weight antioxidant concentration in the plasma samples, the duration of Trolox activity as a function of its concentration in the sample was measured. The activity of antioxidative enzymes in red blood cells was determined using the Misra and Fridovich method and Beers and Sizer method.

Results:

The total plasma antioxidant capacity and the low-molecular-weight antioxidant concentration in the group of patients with metabolically compensated type 2 diabetes were statistically significantly higher than in the group of patients with metabolically uncontrolled diabetes. The activity of antioxidative enzymes was found to be higher in the group of type 2 diabetes patients at the stage of metabolic balance.

Conclusions:

The obtained results confirm the thesis of glucose toxicity and intensification of oxidative stress in patients with diabetes.

The use of vitamin E in type 2 diabetes mellitus

Diabetes mellitus has assumed epidemic proportions in most parts of the world, and it is a major source of morbidity in developed countries. In addition, in several instances, diabetes is associated with a variety of metabolic abnormalities, including abdominal obesity, insulin resistance, hypertension, dyslipidemia, and hyperglycemia. There is considerable evidence that hyperglycemia causes the generation of reactive oxygen species (ROS), ultimately leading to increased oxidative stress in a variety of tissues. In the absence of an appropriate compensatory response by the endogenous antioxidants, such as vitamins C and E, catalase, glutathione, and superoxide dismutase, oxidative stress dominates, resulting in the activation of stress-sensitive intracellular signaling pathways. One of the major consequences is the generation of gene products that cause cellular damage and are ultimately responsible for the late complications of diabetes. The ability of antioxidants to protect against the effects of hyperglycemia in vitro, along with the clinical benefits often reported following antioxidant therapy, supports a causative role of oxidative stress in mediating and/or worsening these abnormalities. This review will focus on the critical assessment of the literature as it relates to the association between oxidative stress and diabetes, followed by the role of oxidative stress in the complications of type 2 diabetes mellitus. Finally, a review of the use of the antioxidant vitamin E will be provided in diabetic patients by assessing and evaluating some of the clinical trials in the literature.

Antioxidant status in type ii diabetes mellitus patients with or without microvascular complications

Introduction. Lipid peroxidation and antioxidant systems are important factors affecting the metabolism of lipoproteins in diabetes mellitus. Objective. The aim of this study was to investigate the lipid and antioxidant parameters in type II diabetes mellitus patients, and also to determine the effect of diabetic complications on these parameters. Method. Lipid status, Oxidized LDL cholesterol, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and plasminogen activator inhibitor (PAI-1) levels in plasma of 50 type II diabetic patients were measured with commercially available kits. Results. The results showed only statistically significant higher levels of triglycerides (3.12?3.9 mmol/l) in diabetics compared with the controls. Ox-LDL cholesterol (84.7?16.9 mmol/l) and SOD activities (913.4?120.3 U/gHb) in type 2 diabetes mellitus were higher than those of the controls, but there was no statistical significance. On the other hand, in patients with diabetes mellitus and complications, LDL cholesterol, PAI-1, SOD and GSH-Px activities were higher but not significantly than those without complications. Triglycerides and Ox-LDL cholesterol were lower in the group of diabetic patients with complications in comparison to the group without complications. Conclusion. These results indicate that antioxidant status may be affected in type II diabetic patients and that the rise in some enzyme activities could be a compensatory mechanism to prevent tissue damage. Our results suggest that the rise in PAI-1 in type II diabetics with complications may be a good marker of vascular endothelial dysfunction.

Effects of hyperglycemia on sperm and testicular cells of Goto-Kakizaki and streptozotocin-treated rat models for diabetes

Diabetes mellitus is a degenerative disease that has deleterious effects on male reproductive function, possibly through an increase in oxidative stress. This study was conducted in order to clarify the mechanisms by which oxidative stress influences animal models for both type 1 (streptozotocin-treated rats, STZ) and type 2 (Goto-Kakizaki (GK) rats) diabetes. We determined the extent of lipid peroxidation, protein oxidation, lactate levels, adenine nucleotides, adenylate energy charge and the activity of glutathione peroxidase, glutathione reductase and lactate dehydrogenase, in isolated testicular cells of control and diabetic rats. We have also correlated these parameters with sperm count and motility. Sperm concentration and motility were decreased in STZ-treated rats. ATP levels were lower in rats treated with STZ for 3 months, in contrast to GK and rats treated with STZ for 1 month, suggesting an adaptative response. STZ-treated rats showed increased lipid peroxidation after 1 week and 3 months of treatment. Glutathione reductase (G-red) activity was found to be higher in GK rats. Glutathione peroxidase activity was lower in GK and rats treated with STZ for 1 month, which is in accordance with the proposal of functional recovery in these animals. We conclude that hyperglycemia has an adverse effect in sperm concentration and motility via changes in energy production and free radical management. Furthermore, both animal models, particularly GK rats and rats treated with STZ for 1 month, present some metabolic adaptations, increasing the efficiency of mitochondrial ATP production, in order to circumvent the deleterious effects promoted by the disease.

Vanadyl sulfate administration protects the streptozotocin-induced oxidative damage to brain tissue in rats

Diabetes mellitus manifests itself in a wide variety of complications and the symptoms of the disease are multifactorial. The present study was carried out to investigate the effects of vanadyl sulfate on biochemical parameters, enzyme activities and brain lipid peroxidation, glutathione and nonenzymatic glycosylation of normal- and streptozotocin-diabetic rats. Streptozotocin (STZ) was administered as a single dose (65 mg/kg) to induce diabetes. A dose of 100 mg/kg vanadyl sulfate was orally administered daily to STZ-diabetic and normal rats, separately until the end of the experiment, at day 60. In STZ-diabetic group, blood glucose, serum sialic and uric acid levels, serum catalase (CAT) and lactate dehydrogenase (LDH) activities, brain lipid peroxidation (LPO) and nonenzymatic glycosylation (NEG) increased, while brain glutathione (GSH) level and body weight decreased. In the diabetic group given vanadyl sulfate, blood glucose, serum sialic and uric acid levels, serum CAT and LDH activities and brain LPO and NEG levels decreased, but brain GSH and body weight increased. The present study showed that vanadyl sulfate exerted antioxidant effects and consequently may prevent brain damage caused by streptozotocin-induced diabetes.

The role of N-acetylcysteine treatment on anti-oxidative status in patients with type II diabetes mellitus

The development of diabetic complications has usually been attributed to the nonenzymic glycation of tissue proteins. Only recently, however, have researchers examined the possible role on free radicals in the pathogenesis of diabetes. In the present study, glutathione (GSH) and major antioxidant enzyme levels in plasma of patients with type II diabetes mellitus were assessed both before and after 3 months of N-acetylcysteine (NAC) therapy. Thirty-two diabetic patients were examined as well as fifteen healthy controls. Before treatment with NAC, glutathione peroxidase (GPx), catalase (CAT), and (GSH) levels of diabetic patients and control subjects showed no significant differences, whereas glutathione S-transferase (GST) levels were higher in type II diabetic patients. Following 3 months of Following NAC supplementation, GSH, GST, and CAT levels were found to be similar to the levels before treatment. On the other hand, GPx activity was significantly lower compared with the values before treatment. According to this finding, NAC treatment could have a positive effect on GPx values in type II diabetic patients showing abnormally high values.

Atorvastatin reduces the plasma lipids and oxidative stress but did not reverse the inhibition of prostacyclin generation by aortas in streptozotocin diabetic rats

The effect of atorvastatin (Lipitor) on diabetes-induced changes in plasma lipids, oxidative stress and the ability of aortic tissues to generate prostacyclin was studied in streptozotocin diabetic rats. In diabetic rats, plasma total cholesterol, triglycerides and serum glucose significantly increased compared to nondiabetic rats. Atorvastatin administration to diabetic rats did not affect hyperglycemia but significantly reduced plasma total cholesterol and triglycerides compared to diabetic rats. The oxidative stress markers urinary isoprostane, liver thiobarbituric acid reactive substances (TBARS) and plasma protein carbonyl content significantly increased in diabetic rats compared to nondiabetic rats. Atorvastatin admnistration to diabetic rats significantly reduced oxidative stress levels compared to diabetic rats, but urinary isoprostane and liver TBARS remained significantly higher than nondiabetic rats. Prostacyclin (PGI(2)) generation by aortic tissues significantly decreased in diabetic rats compared to nondiabetic rats. Atorvastatin administration to diabetic rats did not reverse that inhibition. These results were discussed in the light of the possible effects of hyperglycemia and statins on NAD(P)H-oxidase and cyclooxygenase-2 activities and the genetic difference between rats and other mammals regarding the level of vascular superoxide dismutase (SOD) activity.

Hepatic changes in the acute phase of streptozotocin (SZ)-induced diabetes in mice

We have reported the streptozotocin (SZ)-induced hepatic lesions in the subacute phase (4 to 12 weeks after the treatment), which are characterized by appearance of oncocytic hepatocytes, cytomegalic hepatocytes and bile duct hyperplasia. In this study, we focused on the acute phase (6 to 48 hours after the treatment) of the SZ-induced hepatic lesions of mice to clarify the onset of the hepatic alterations, especially before the induction of hyperglycemia. Livers were taken from 8-week-old Crj:CD-1 (ICR) male mice at 6, 12, 24, 36 and 48 hours after the 200 mg/kg b.w. of SZ-injection. SZ-induced hyperglycemia was noted at 36 and 48 hours after the treatment, but the hepatic changes including lipid peroxidation, mitochondrial swelling, peroxisome proliferation and inhibition of hepatocyte proliferation occurred before the elevation of the serum glucose levels. The present findings indicate the direct effects of SZ on hepatocytes rather than the secondary effects of diabetes, and certain correlations between the hepatocytic changes in the acute phase and those in the subacute one. In addition, ulcer and submucosal edema of the gallbladder were observed at 36 or 48 hours after the SZ-treatment, which can be a novel finding in SZ-treated animal.

Influence of treatment of diabetic rats with combinations of pycnogenol, ?-carotene, and ?-lipoic acid on parameters of oxidative stress

Treatment with antioxidants may act more effectively to alter markers of free radical damage in combinations than singly. This study has determined whether treatment with combinations of pycnogenol, beta-carotene, and alpha-lipoic acid was more effective at reducing oxidative stress in diabetic rats than treatment with these antioxidants alone. It is not feasible, based on this study, to assume that there are interactive effects that make combinations of these antioxidants more effective than any one alone to combat oxidative stress. Female Sprague-Dawley rats, normal and streptozotocin-induced diabetic, were treated (10 mg/kg/day ip for 14 days) with pycnogenol, beta-carotene, pycnogenol + beta-carotene, or pycnogenol + beta-carotene + alpha-lipoic acid; controls were untreated. Concentrations of thiobarbituric acid reactive substances, glutathione and glutathione disulfide, and activities of glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase were measured in liver, kidney, and heart. Four types of effects were observed: (1) treatment with beta-carotene alone either reversed (cardiac glutathione disulfide) or elevated (cardiac glutathione, hepatic glutathione peroxidase activity) levels seen in diabetic animals; (2) beta-carotene alone produced no effect, but pycnogenol both alone and in combinations elevated (renal glutathione peroxidase and glutathione reductase activities, hepatic glutathione reductase activity and glutathione disulfide) or depressed (cardiac glutathione disulfide) levels seen in untreated diabetic animals; (3) all treatments with antioxidants, either alone or in combination, either normalized (lipid peroxidation in all tissues), elevated (hepatic GSH, cardiac glutathione peroxidase activity), or had no effect on (activities of hepatic catalase and superoxide dismutase in all tissues) levels seen in diabetic animals; (4) in only one case (cardiac glutathione reductase activity) levels in diabetic animals treated with combinations of antioxidants were normal, but elevated in animals treated with either antioxidant alone. Antioxidant effects seem to be dependent on the nature of the antioxidant used and not on combination effects.

Oxidative stress and glucose levels in a population-based sample

OBJECTIVES

To examine the relationship between markers of oxidative status and glucose on a population basis.

STUDY DESIGN AND SETTING

We report here on a population-based sample of 1315 women and 981 men, aged 35-79 years, randomly selected from residents of Erie and Niagara Counties in western New York between 1996 and 1999. Thiobarbituric reactive substances (TBARS), erythrocyte glutathione (GSH) and plasma glutathione peroxidase (GSH-Px) were measured as markers of oxidative status. Study sample was categorized by quartiles of glucose, degree of abnormality of fasting glucose, and level of metabolic control in patients with diabetes.

RESULTS

Men and women in the uppermost quartiles of glucose had higher levels of TBARS (men: Quartile 4 = 1.55 +/- 0.03, Quartile 1 = 1.36 +/- 0.03, women: 1.49 +/- 0.02, 1.30 +/- 0.02 nmol/ml) and lower levels of GSH (men: Quartile 4 = 1.57 +/- 0.03, Quartile 1 = 1.69 +/- 0.03, women: 1.71 +/- 0.03, 1.97 +/- 0.0 mmol/l packed RBCs). In women, compared with normal fasting glucose, impaired fasting glucose was associated with higher levels of TBARS (1.29 +/- 0.01 vs. 1.84 +/- 0.04 nmol/ml), lower levels of GSH (1.85 +/- 0.02 vs. 1.76 +/- 0.05 mmol/l packed RBCs), and higher GSH-Px activity (618.94 +/- 2.64 vs. 644.77 +/- 8.90 IU/l). In women, abnormal fasting glucose was associated with higher levels of TBARS (1.84 +/- 0.04 nmol/ml), lower levels of GSH (1.68 +/- 0.06 mmol/l packed RBCs), and higher levels of GSH-Px (647.72 +/- 9.87 IU/l) than normal or impaired fasting glucose. In men, abnormal fasting glucose was associated with higher TBARS (1.76 +/- 0.04 vs. 1.37 +/- 0.07 nmol/ml), and lower GSH (1.62 +/- 0.05 vs. 2.78 +/- 0.02 mmol/l packed RBCs), than normal fasting glucose. Poor metabolic control was associated with higher TBARS (men: 2.07 +/- 0.08 vs. 1.33 +/- 0.14 nmol/l, women: 2.02 +/- 0.09 vs. 1.35 +/- 0.18 nmol/l) and GSH-Px activity (men: 654.34 +/- 13.45 vs. 599.86 +/- 24.76, women: 660.61 +/- 13.25 vs. 579.42 +/- 27.42 IU/l).

CONCLUSIONS

Glucose levels play a role in determining oxidative status in a population sample. The balance between oxidative and antioxidant processes appears to be sensitive to glucose levels with moderate elevations of glucose affecting the oxidative status.

Protective role of Scoparia dulcis plant extract on brain antioxidant status and lipidperoxidation in STZ diabetic male Wistar rats

Background

The aim of the study was to investigate the effect of aqueous extract of Scoparia dulcis on the occurrence of oxidative stress in the brain of rats during diabetes by measuring the extent of oxidative damage as well as the status of the antioxidant defense system.

Methods

Aqueous extract of Scoparia dulcis plant was administered orally (200 mg/kg body weight) and the effect of extract on blood glucose, plasma insulin and the levels of thiobarbituric acid reactive substances (TBARS), hydroperoxides, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and reduced glutathione (GSH) were estimated in streptozotocin (STZ) induced diabetic rats. Glibenclamide was used as standard reference drug.

Results

A significant increase in the activities of plasma insulin, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase and reduced glutathione was observed in brain on treatment with 200 mg/kg body weight of Scoparia dulcis plant extract (SPEt) and glibenclamide for 6 weeks. Both the treated groups showed significant decrease in TBARS and hydroperoxides formation in brain, suggesting its role in protection against lipidperoxidation induced membrane damage.

Conclusions

Since the study of induction of the antioxidant enzymes is considered to be a reliable marker for evaluating the antiperoxidative efficacy of the medicinal plant, these findings suggest a possible antiperoxidative role for Scoparia dulcis plant extract. Hence, in addition to antidiabetic effect, Scoparia dulcis possess antioxidant potential that may be used for therapeutic purposes.