The evaluation of altered redox status in plasma and mitochondria of acute and chronic diabetic rats

Effect of oligosaccharides on the antioxidant, lipid and inflammatory profiles of rats with streptozotocin-induced diabetes mellitus

Prebiotics, gut microbiota-fermentable substances, delay the development of type I diabetes. In the present study, we investigated the effect of two prebiotics (galacto-oligosaccharides and xylo-oligosaccharides) on the antioxidant protection, lipid profile, and inflammatory activity of rats with streptozotocin-induced diabetes. The following markers were studied - malondialdehyde, 8-hydroxy-2'-deoxyguanosine, ferric reducing ability of plasma (FRAP), triacylglycerols, total cholesterol (TC), high-density lipoproteins, C-reactive protein (CRP), and interleukin-6. Diabetes was induced in male Wistar experimental rats by streptozotocin injection, while the non-diabetic controls were injected with saline. Afterward the oligosaccharides were administered orally to the experimental animals. The blood collected following the decapitation was analyzed by ELISA. A modified protocol was used only for measuring the FRAP values. The galacto-oligosaccharides and xylo-oligosaccharides lowered the malondialdehyde levels in the diabetic rats (p < 0.05). The galacto-oligosaccharides decreased the serum levels of 8-hydroxy-2'-deoxyguanosine (p = 0.01), while the xylo-oligosaccharides increased the FRAP (p < 0.05) in the experimental animals. None of the oligosaccharides affected triacylglycerol and interleukin-6 concentrations, but the galacto-oligosaccharides decreased the TC and CRP levels in the diabetic animals. Both oligosaccharides exert a beneficial effect on the antioxidant protection of the diabetic rats, but have a minor effect on their lipid and inflammatory profiles.

The efficacy of Origanum majorana nanocubosomal systems in ameliorating submandibular salivary gland alterations in streptozotocin-induced diabetic rats

Diabetes mellitus is a challenging health problem. Salivary gland dysfunction is one of its complications. Current treatments possess numerous adverse effects. Therefore, herbal extracts have emerged as a promising approach for safe and effective treatment. However, they are required in large doses to achieve the desired effect. Accordingly, Origanum majorana extract (OE) was incorporated into nano-sized systems to enhance its biological effects at lower dosages. OE was standardized against rosmarinic acid (RA) and then loaded into nano-cubosomal (NC) systems via a 2³ full-factorial design. Two optimum nano-systems at different drug loads (2.08 or 1.04 mg-RA/mL) were selected and assessed in vivo to compare their effects in streptozotocin-induced diabetic rats against conventional OE (2.08 mg-RA/mL). Blood glucose was evaluated weekly. Submandibular salivary glands were processed for histopathological examination and nuclear factor-erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap1), and p38-MAPK gene expression analysis. NC systems were successfully prepared and optimized where the optimum systems showed nano-sized vesicles (210.4–368.3 nm) and high zeta potential values. In vivo results showed a significant lower blood glucose in all treated groups, with an exceptional reduction with NC formulations. Marked histopathological improvement was observed in all OE-treated groups, with OE-NC4 (2.08 mg-RA/mL) demonstrating the best features. This was supported by RT-PCR; where the OE-NC4 group recorded the highest mean value of Nrf2 and the least mean values of Keap1 and p38-MAPK, followed by OE-NC3 and OE groups. In conclusion, OE-loaded NC enhanced the anti-hyperglycemic effect of OE and ameliorated diabetic gland alterations compared to conventional OE. Thus, cubosomal nano-systems could be anticipated as potential carriers for the best outcome with OE.

Proatherogenic Importance of Carbamylation-induced Protein Damage and Type 2 Diabetes Mellitus: A Systematic Review

INTRODUCTION & BACKGROUND

Protein carbamylation is a non-enzymatic and irreversible posttranslational process. It affects functions of numerous enzymes, hormones and receptors playing several roles in diabetes pathogenesis by changing their native structures. Detrimental consequences of oxidative protein damage comprise, but are not limited to glyoxidation, lipoxidation and carbonylation reactions. Since the carbamylated plasma proteins are strongly related to the glycemic control parameters of diabetes, they may have an additive value and emerge as potential biomarkers for the follow up, prognosis and treatment of diabetes mellitus.

METHODS & RESULTS

To conduct our systematic review, we used PubMed and Semantic Scholar, and used 'Protein carbamylation and diabetes' and 'Protein carbamylation and atherosclerosis' as keywords and looked into about five hundred manuscripts. Manuscripts that are not in English were excluded as well as manuscripts that did not mention carbamylation to maintain the focus of the present article. Similar to glycation, carbamylation is able to alter functions of plasma proteins and their interactions with endothelial cells and has been shown to be involved in the development of atherosclerosis.

CONCLUSION

At this stage, it seems clear that protein carbamylation leads to worse clinical outcomes. To improve patient care, but maybe more importantly to improve healthcare-prevention, we believe the next stage involves understanding how exactly protein carbamylation leads to worse outcomes and when and in what group of people anti-carbamylation therapies must be employed.

Renal Tissue Damages and Its Antioxidant Status Improved by Crab Shell Extract in Streptozotocin-induced Diabetic Rat

BACKGROUND

Diabetic nephropathy is a complex and multifactorial adverse effect of diabetes mellitus (DM). Crab shell as a natural product is supposed to have antioxidant effect which is one of the important mechanisms to improve DM. The aim of this study was to investigate the effect of crab shell extract (CSE) on the histopathology and antioxidant status of kidney in diabetic rats.

MATERIALS AND METHODS

Forty-two adult Wistar rats (210 ± 10 g) were divided into six groups (n = 7). Streptozotocin (50 mg/kg) was administered interaperitonealy (IP) for inducing diabetes. Rats were treated for 14 days by CSE with 100, 200, and 400 mg/kg doses IP. Fasting blood glucose, body, and renal weight were evaluated. The antioxidant status of kidney's tissue was evaluated by determining the level of ferric-reducing antioxidant power (FRAP). Furthermore, urine samples were used to determine nitric oxide (NO) levels. Microscopic slides were prepared to compare kidney histology between groups. Data were analyzed by one-way analysis of variance with post hoc Tukey's test, and P < 0.05 was considered statistically significant.

RESULTS

CSE induced a significant reduction in blood glucose (P = 0.01) and a significant increase in total antioxidant capacity (FRAP) (P = 0.004). Furthermore, urine NO was decreased significantly (P = 0.000). The extract improved renal tissue changes caused by diabetes.

CONCLUSION

CSE improved antioxidant status and diabetic histological changes of rat kidney, and it could be an alternative complementary therapy in diabetic-associated disorders.

The effects of delta-9-tetrahydrocannabinol on Krüppel-like factor-4 expression, redox homeostasis, and inflammation in the kidney of diabetic rat

Diabetes mellitus is a complex, multifactorial disorder that is attributed to pancreatic β cell dysfunction. Pancreatic β cell dysfunction results in declining utilization of glucose by peripheral tissues as kidney and it leads to nephropathy. Excessive production and accumulation of free radicals and incapable antioxidant defense system lead to impaired redox status. Macromolecular damage may occur due to impaired redox status and also immune imbalance. Δ9-Tetrahydrocannabinol (THC) is the main active ingredient in cannabis. THC acts as an immunomodulator and an antioxidant agent. Our aim was to evaluate the effects of THC in the diabetic kidney. We analyzed macromolecular damage biomarkers as protein carbonyl (PCO), lipid hydroperoxide (LHP), malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and antioxidant defense system biomarkers as thiol fractions (T-SH, NP-SH, P-SH) and Cu/Zn-superoxide dismutase activity for the antioxidative effects of THC. Furthermore, mRNA expression of Krüppel-like factor-4, secreted immunopositive cell number changes of interleukin-6, nuclear factor κβ (NF-κβ), and peroxisome proliferator-activated receptor-γ and tumor necrosis factor α (TNF-α) levels were analyzed for the immunomodulatory activity of THC. Diabetic rats showed significantly increased levels of PCO, LHP, MDA, and 8-OHdG when compared with controls (P < 0.05 for each parameter). THC significantly reduced the elevated levels of PCO and 8-OHdG (P < 0.05 for both parameters) and also LHP and MDA levels were insignificantly reduced by THC. Also, thiol fractions insignificantly increased in THC administered diabetic kidney when compared with diabetic rats. The NF-κβ cell number significantly decreased in the diabetic rats treated with THC compared with the diabetic group. According to our data, THC has ameliorative effects on the impaired redox status of diabetic kidney and also it acts as an immunomodulator. Therefore, THC might be used as a therapeutic agent for diabetic kidneys but its usage in the healthy kidney may show adverse effects.

Improvement in Serum Biochemical Alterations and Oxidative Stress of Liver and Pancreas following Use of Royal Jelly in Streptozotocin-Induced Diabetic Rats

OBJECTIVE

This study aimed to evaluate the effects of royal jelly (RJ) on serum biochemical alterations and oxidative stress status in liver and pancreas of streptozotocin (STZ)- induced diabetic rats.

MATERIALS AND METHODS

In this experimental study, thirty two male Wistar rats were divided into the following four groups (n=8/group): i. Control (C), ii. Diabetic (D), iii. Royal jelly (R), and iv. Royal jelly-treated diabetic (D/R) groups. Diabetes was induced by single intraperitoneal (IP) injection of STZ (60 mg/kg). The RJ [100 mg/kg body weight (BW)] was administered orally for 42 days. Blood samples were used to determine serum levels of insulin, high density lipoprotein cholesterol (HDL-c), total protein (TP), albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and fasting blood glucose (FBG). Also, the antioxidant status was evaluated by determining the levels of malondialdehyde (MDA), catalase (CAT) and ferric reducing antioxidant power (FRAP) in liver and pancreas. Data were analyzed by one-way analysis of variance (ANOVA) with P<0.05 as the significant level.

RESULTS

STZ-induced diabetic rats showed a significant elevation in the serum levels of AST, ALT, ALP and FBG, whereas there was a significant decrease in serum levels of insulin, albumin, HDL-c and TP (P<0.05). Treatment of the diabetic rats with RJ restored the changes of the above parameters to their normal levels (P<0.05). In addition, RJ significantly improved reduced levels of FRAP and CAT as well as high MDA level in liver and pancreas (P<0.05).

CONCLUSION

RJ improves oxidative damage induced by STZ in the liver and pancreas of rats; therefore, it can be considered as an effective and alternative treatment for diabetes.

Oxidative Damage to the Salivary Glands of Rats with Streptozotocin-Induced Diabetes-Temporal Study: Oxidative Stress and Diabetic Salivary Glands

Objective. This study evaluated oxidative damage caused to the salivary glands in streptozotocin-induced diabetes (DM). Materials and Methods. Rats were divided into 4 groups: groups 1 and 2, control rats, and groups 3 and 4, DM rats. 8-Hydroxy-2'-deoxyguanosine (8-OHdG), protein carbonyl (PC), 4-hydroxynonenal protein adduct (4-HNE), oxidized and/or MDA-modified LDL-cholesterol (oxy-LDL/MDA), 8-isoprostanes (8-isoP), and oxidative stress index (OSI) were measured at 7 (groups 1 and 3) and 14 (groups 2 and 4) days of experiment. Results. The unstimulated salivary flow in DM rats was reduced in the 2nd week, while the stimulated flow was decreased throughout the duration of the experiment versus control. OSI was elevated in both diabetic glands in the 1st and 2nd week, whereas 8-isoP and 8-OHdG were higher only in the parotid gland in the second week. PC and 4-HNE were increased in the 1st and 2nd week, whereas oxy-LDL/MDA was increased in the 2nd week in the diabetic parotid glands. Conclusions. Diabetes induces oxidative damage of the salivary glands, which seems to be caused by processes taking place in the salivary glands, independently of general oxidative stress. The parotid glands are more vulnerable to oxidative damage in these conditions.

Oxidative stress and anti-oxidant status in diabetic rat liver: effect of plant polyphenols

Increased evidence in role of oxidative stress and grape seed extract (GSE) in diabetes and its complication led us to investigate the changes of oxidative stress and anti-oxidant defence in liver tissue of diabetic rats and possible effects of GSE. Diabetes was induced by a single intraperitoneal injection of streptozotocin. Seven days after STZ injection four groups were formed: Control, GSE-supplemented control, diabetic and GSE-supplemented diabetic and GSE was given for 6 weeks. Malondialdehyde levels and xanthine oxidase activities were not different among the groups. However, nitric oxide (NO) levels were higher in diabetic and GSE supplemented groups compared with non-diabetic and non-supplemented groups, respectively. Total anti-oxidant activity (TAA) was lower in diabetic groups compared with their non-diabetic controls and it was not affected by GSE. In conclusion, GSE supplementation has limited protective effect in liver tissue of diabetic rats via affecting NO levels and was not affecting TAA.

[L-cysteine influx in diabetic erythrocytes]

Erythrocyte oxidative stress has been implicated in the pathogenesis of diabetes mellitus, and the deficiency of antioxidant defense by the glutathione (GSH) pathway is thought to be one of the factors responsible for development of complications in diabetes. Erythrocytes require L-cysteine for thesynthesis of GSH and the rate of synthesis is determined only by L-cysteine availability. In the present study we have found that the L-cysteine influx in erythrocytes from type 2 diabetic patients was significantly lower compared to age-matched controls. The decreased influx may be one of the factors leading to low GSH concentration observed in type 2 diabetes. Since L-cysteine is the limiting amino acid in GSH synthesis, any strategy aimed to increase L-cysteine influx in erythrocytes may be beneficial for type 2 diabetic patients.

Prediction of diabetic retinopathy: role of oxidative stress and relevance of apoptotic biomarkers

Diabetic retinopathy (DR) is the foremost cause of blindness in working-aged worldwide; it is characterized by vascular and neuronal degeneration. Features of DR include leukocyte adhesion, increased vascular permeability, neovascularization and neuronal cell death. Early diagnosis and intervention are important to prevent or at least ameliorate the development of DR. Recent reports indicate that pathophysiological mechanisms leading to diabetic retinopathy include oxidative stress and retinal cell death cascades. Circulating biomarkers of oxidative stress such as malondialdehyde (MDA), thiobarbituric acid reacting substances (TBARS), conjugated diene (CD), advanced oxidation protein products (AOPP), protein carbonyl, 8-hydroxydeoxyguanosin (8-OHdG), nitrotyrosine, and F(2) isoprostanes and pro-apoptosis molecules (caspase-3, Fas, and Bax) are associated with increased susceptibility to develop DR in diabetic subjects. Thus, identification of oxidative stress and cell death biomarkers in diabetic patients could be in favor of predicting, diagnosis, and prevention of DR, and to target for novel therapeutic interventions.

Attenuation of oxidative stress in streptozotocin-induced diabetic rats by Eucalyptus globulus

In traditional medicine, Eucalyptus globulus (eucalyptus) was used for the treatment of diabetes mellitus. Hyperglycemia in diabetes has been associated with increased formation of reactive oxygen species (ROS) and oxidative damage to tissue compounds. The aim of this study was to evaluate the effects of eucalyptus in the diet (20 g/Kg) and drinking water (2.5 g/L) on lipid peroxidation, protein oxidation and antioxidant power in plasma and liver homogenate, as well as glycated-Hb (HbA(1C)) of blood in streptozotocin-induced diabetic rats for a period of 4 weeks. Diabetes induced in rats by a single intraperitoneal injection of streptozotocin (STZ, 65 mg/Kg). At the end of the treatment period, the level of plasma glucose, plasma and liver malondialdehyde (MDA, the main product of lipid peroxidation), protein carbonyl (PC, one of the protein oxidation products) and HbA(1C) increased and ferric reducing antioxidant power (FRAP) decreased in diabetic rats compared to normal rats. Eucalyptus administration for 4 weeks caused a significant decrease in the plasma glucose levels, plasma and liver MDA, PC and HbA(1C), also a concomitant increase in the levels of FRAP in diabetic treated rats. In conclusion, the present study showed that eucalyptus posses antioxidant activities. Eucalyptus probably restores antioxidant power, due to the improved hyperglycemia in streptozotocin-induced diabetic rats.

AOPP and its relations with selected markers of oxidative/antioxidative system in type 2 diabetes mellitus

BACKGROUND

The aim of this study was to evaluate the selected components of the oxidative/antioxidative system in T2DM; estimation of relationships between them; search for the more expressive one and examine their alterations in angiopathy and obesity.

METHODS

In 94 diabetic patients and 36 healthy people, plasma levels of TRAP, as a marker of antioxidative defence, as well as concentrations of CO, SH, and NH(2) groups and AOPP, as markers of oxidative protein damage (OPD) were determined.

RESULTS

Patients had significantly lower levels of TRAP and SH groups, as well as higher NH(2), CO and AOPP in comparison to control. Significant correlation was observed between TRAP and SH groups and AOPP as well as between AOPP and SH and CO groups. Concentration of AOPP was significantly higher in the macroangiopathy and obese subgroups.

CONCLUSIONS

Our results support the idea that diabetes mellitus is a complex metabolic disorder with oxidant/antioxidant defence disturbances. Among the studied parameters AOPP showed the most expressive raise in plasma of diabetic patients and significant differences between their subgroups with vascular complications and overweight. We can conclude that AOPP seems to be considered as a useful marker to estimate the degree of OPD in diabetic patients.

Dietary caloric restriction improves the redox status at the onset of diabetes in hepatocytes of streptozotocin-induced diabetic rats

Enhanced production of free radicals and oxidative stress induced by hyperglycemia play a central role in the pathogenesis of diabetes and its complications. This study assessed the attenuation by dietary caloric restriction on the oxidative and lipid peroxidative effects of diabetes in the liver through reduction in body and organ weights and concomitant metabolic changes. Three-month-old male Wistar rats were subjected to ad libitum feeding and 30% caloric restriction for 9 weeks before induction of diabetes by intraperitoneal injection of 35 mg/kg body weight streptozotocin. The animals were sacrificed 2 weeks after streptozotocin treatment depicting the onset of diabetes. Caloric restriction significantly reduced the organ weights (p<0.01), malondialdehyde (p<0.01) and catalase activity (p<0.01), but significantly increased glutathione reductase activity (p<0.01), and GSH/GSSG ratios (p<0.05). Caloric restriction also non-significantly reduced reactive oxygen species, superoxide dismutase and oxidized glutathione but increased glutathione peroxidase activity and reduced glutathione levels in the diabetic rats. Our data indicate a decrease in lipid peroxidation, improvement in the antioxidant defense systems and restoration of the redox status in the liver by caloric restriction. Therefore, this could provide a non-invasive antioxidant therapy early in diabetes to prevent the development of the complications associated with the disease.