Blockade of oxidative stress by vitamin C ameliorates albuminuria and renal sclerosis in experimental diabetic rats

Mitochondrial Toxic Effects of Antiepileptic Drug Valproic Acid on Mouse Kidney Stem Cells

Valproic acid (VPA) is a histone deacetylase inhibitor that is used mainly as an antiepileptic and anticonvulsant drug. The side effects of VPA usually appears as hepatic injury and various metabolic disorders. On the other hand, it is rarely reported to cause kidney injury. Despite the many studies on the influence of VPA exposure on the kidneys, the specific mechanism remains unclear. This study examined the changes after VPA treatment to the mouse kidney stem cells (mKSCs). VPA triggers an increase in mitochondrial ROS, but there was no change in either mitochondrial membrane potential or the mitochondrial DNA copy number in mKSCs. The VPA treatment increased the mitochondrial complex III but decreased complex V significantly compared to the DMSO treatment as a control. The inflammatory marker (IL-6) and the expression of the apoptosis markers (Caspase 3) and were increased by VPA. In particular, the expression of the podocyte injury markers (CD2AP) was increased significantly. In conclusion, VPA exposure has adverse effects on mouse kidney stem cells.

Recent Advances in the Emerging Therapeutic Strategies for Diabetic Kidney Diseases

Diabetic kidney disease (DKD) is one of the most common causes of end-stage renal disease worldwide. The treatment of DKD is strongly associated with clinical outcomes in patients with diabetes mellitus. Traditional therapeutic strategies focus on the control of major risk factors, such as blood glucose, blood lipids, and blood pressure. Renin–angiotensin–aldosterone system inhibitors have been the main therapeutic measures in the past, but the emergence of sodium–glucose cotransporter 2 inhibitors, incretin mimetics, and endothelin-1 receptor antagonists has provided more options for the management of DKD. Simultaneously, with advances in research on the pathogenesis of DKD, some new therapies targeting renal inflammation, fibrosis, and oxidative stress have gradually entered clinical application. In addition, some recently discovered therapeutic targets and signaling pathways, mainly in preclinical and early clinical trial stages, are expected to provide benefits for patients with DKD in the future. This review summarizes the traditional treatments and emerging management options for DKD, demonstrating recent advances in the therapeutic strategies for DKD.

Oxidative stress in the pathophysiology of type 2 diabetes and related complications: Current therapeutics strategies and future perspectives

Type 2 diabetes (T2DM) is a persistent metabolic disorder rising rapidly worldwide. It is characterized by pancreatic insulin resistance and β-cell dysfunction. Hyperglycemia induced reactive oxygen species (ROS) production and oxidative stress are correlated with the pathogenesis and progression of this metabolic disease. To counteract the harmful effects of ROS, endogenous antioxidants of the body or exogenous antioxidants neutralise it and maintain bodily homeostasis. Under hyperglycemic conditions, the imbalance between the cellular antioxidant system and ROS production results in oxidative stress, which subsequently results in the development of diabetes. These ROS are produced in the endoplasmic reticulum, phagocytic cells and peroxisomes, with the mitochondrial electron transport chain (ETC) playing a pivotal role. The exacerbated ROS production can directly cause structural and functional modifications in proteins, lipids and nucleic acids. It also modulates several intracellular signaling pathways that lead to insulin resistance and impairment of β-cell function. In addition, the hyperglycemia-induced ROS production contributes to micro- and macro-vascular diabetic complications. Various in-vivo and in-vitro studies have demonstrated the anti-oxidative effects of natural products and their derived bioactive compounds. However, there is conflicting clinical evidence on the beneficial effects of these antioxidant therapies in diabetes prevention. This review article focused on the multifaceted role of oxidative stress caused by ROS overproduction in diabetes and related complications and possible antioxidative therapeutic strategies targeting ROS in this disease.

Therapeutic role of Azadirachta indica leaves ethanolic extract against diabetic nephropathy in rats neonatally induced by streptozotocin

Diabetic nephropathy (DN) is manifested by chronic loss of renal function due to damage of glomeruli and renal tubules. Therefore, this study is mainly designed to evaluate the therapeutic role of Azadiracta indica (neem) leaves extract as a novel approach for treatment of DN in rats neonatally induced by streptozotocin (STZ). For this study, 40 offspring were selected after parturition and categorized into four groups (n = 10). Group1: control group, group 2: neem leaves extract supplemented group, group 3: diabetic group that injected with a single dose of STZ and group 4: diabetic group treated with neem extract. The results revealed deleterious histological and ultrstructural changes in the renal tissues of diabetic rats. Such changes included atrophied glomeruli, dilated renal cortical tubules and scattered hemorrhage spots, thickening of glomerular basement membrane, expansion of mesangial matrix and pyknotic podocyte. Additionally, the proximal convoluted tubule and distal tubule showed cytoplasmic vacuolation, vacuolated mitochondria, scattered lipid droplets, lost microvilli and disrupted basal lamina and basal infoldings. Moreover, significant decreased levels of serum antioxidants (SOD&CAT) and significant increased levels of serum MDA, urea and creatinine were noticed in diabetic rats. Neem leaves extract successfully alleviated the histological and ultrastructural as well as biochemical changes induced by diabetes.

Carbamylated Erythropoietin Alleviates Kidney Damage in Diabetic Rats by Suppressing Oxidative Stress

The oxidative stress response plays an important role in the occurrence and development of diabetic kidney disease (DKD). It has become a new treatment target for DKD. In the current study, the effects of carbamylated erythropoietin (CEPO) on renal oxidative stress and damage in diabetic rats were examined. Thirty Sprague Dawley rats were intraperitoneally administered with 60 mg/kg streptozotocin to establish the diabetes model. The diabetic rats were randomly allocated into 4 groups (n=6 each): diabetes model group (DM group), DM + CEPO treatment group (DC group), DM + CEPO + EPO receptor (EPOR) blocking peptide treatment group (DCEB group), and DM + CEPO + CD131 blocking peptide treatment group (DCCB group). Meanwhile, a normal control group (NC group, n=6) was set up. Kidney tissues and blood samples were obtained for evaluation of oxidative stress and renal function. The results showed that diabetic rats exhibited increased oxidative stress in the kidney and early pathological changes associated with DKD. Treatment with CEPO reduced oxidative stress and attenuated renal dysfunction. However, diabetic rats treated with the combination of CEPO and EPOR blocking peptide or CD131 blocking peptide showed increased oxidative stress and reduced renal function when compared with CEPO treatment alone group. These results suggested that CEPO can protect against kidney damage in DKD by inhibiting oxidative stress injury via EPOR-CD131 heterodimers.

The basement membrane as a structured surface - role in vascular health and disease

The basement membrane (BM) is a thin specialized extracellular matrix that functions as a cellular anchorage site, a physical barrier and a signaling hub. While the literature on the biochemical composition and biological activity of the BM is extensive, the central importance of the physical properties of the BM, most notably its mechanical stiffness and topographical features, in regulating cellular function has only recently been recognized. In this Review, we focus on the biophysical attributes of the BM and their influence on cellular behavior. After a brief overview of the biochemical composition, assembly and function of the BM, we describe the mechanical properties and topographical structure of various BMs. We then focus specifically on the vascular BM as a nano- and micro-scale structured surface and review how its architecture can modulate endothelial cell structure and function. Finally, we discuss the pathological ramifications of the biophysical properties of the vascular BM and highlight the potential of mimicking BM topography to improve the design of implantable endovascular devices and advance the burgeoning field of vascular tissue engineering.

Glucose and Blood Pressure-Dependent Pathways-The Progression of Diabetic Kidney Disease

The major clinical associations with the progression of diabetic kidney disease (DKD) are glycemic control and systemic hypertension. Recent studies have continued to emphasize vasoactive hormone pathways including aldosterone and endothelin which suggest a key role for vasoconstrictor pathways in promoting renal damage in diabetes. The role of glucose per se remains difficult to define in DKD but appears to involve key intermediates including reactive oxygen species (ROS) and dicarbonyls such as methylglyoxal which activate intracellular pathways to promote fibrosis and inflammation in the kidney. Recent studies have identified a novel molecular interaction between hemodynamic and metabolic pathways which could lead to new treatments for DKD. This should lead to a further improvement in the outlook of DKD building on positive results from RAAS blockade and more recently newer classes of glucose-lowering agents such as SGLT2 inhibitors and GLP1 receptor agonists.

Curcumin ameliorates atrophy of seminal vesicle via reduction of oxidative stress in castrated mice

Background

The growth and function of seminal vesicle are dependent on androgen. This study was conducted to investigate the role of oxidative stress in castration-induced seminal vesicle atrophy and to explore the effects of curcumin, an antioxidant extracted from rhizome of turmeric, on seminal vesicle of castrated mice.

Methods

C57BL/6J mice were randomly divided into three groups: control, castration, and castration with curcumin (n = 10 for each group). After surgical castration, mice in the curcumin treatment group received intragastric administration of curcumin at 100 mg/kg body weight for 4 weeks, whereas mice in the other two groups were treated with olive oil. After that, the body weight, seminal vesicle weight and serum testosterone of mice were measured. Apoptosis and oxidative stress levels in seminal vesicle were also determined.

Results

After castration, both the weight and size of seminal vesicle decreased dramatically. The expression of three NADPH oxidase (NOX) subtypes: NOX1, NOX2 and NOX4, increased in seminal vesicle of castrated mice, resulting in high level oxidative stress. The ratio of Bax to Bcl-2 was also elevated after castration, accompanied by enhanced caspase3 activity. Additionally, castration increased the number of apoptotic cells in seminal vesicle. Curcumin treatment could inhibit the expression of NOX1, NOX2 and NOX4, decreasing oxidative stress and apoptosis. The atrophy of seminal vesicle caused by castration was ameliorated by curcumin.

Conclusion

Castration could cause atrophy of seminal vesicle probably via inducing oxidative stress. Curcumin treatment could reduce the oxidative stress in seminal vesicle by decreasing the expression of NOX1, NOX2 and NOX4, thereby ameliorating apoptosis and atrophy of seminal vesicle. Oxidative stress might play a role in castration-induced seminal vesicle atrophy.

Diabetic nephropathy: an insight into molecular mechanisms and emerging therapies

Introduction: Diabetic kidney disease (DKD) is a major cause of morbidity and mortality in diabetes and is the most common cause of proteinuric and non-proteinuric forms of end-stage renal disease (ESRD). Control of risk factors such as blood glucose and blood pressure is not always achievable or effective. Significant research efforts have attempted to understand the pathophysiology of DKD and develop new therapies. Areas covered: We review DKD pathophysiology in the context of existing and emerging therapies that affect hemodynamic and metabolic pathways. Renin-angiotensin system (RAS) inhibition has become standard care. Recent evidence for renoprotective activity of SGLT2 inhibitors and GLP-1 agonists is an exciting step forward while endothelin receptor blockade shows promise. Multiple metabolic pathways of DKD have been evaluated with varying success; including mitochondrial function, reactive oxygen species, NADPH oxidase (NOX), transcription factors (NF-B and Nrf2), advanced glycation, protein kinase C (PKC), aldose reductase, JAK-STAT, autophagy, apoptosis-signaling kinase 1 (ASK1), fibrosis and epigenetics. Expert opinion: There have been major advances in the understanding and treatment of DKD. SGLT2i and GLP-1 agonists have demonstrated renoprotection, with novel therapies under evaluation. Addressing the interaction between hemodynamic and metabolic pathways may help achieve prevention, attenuation or even reversal of DKD.

Natural antioxidants in the treatment and prevention of diabetic nephropathy; a potential approach that warrants clinical trials

Diabetic nephropathy is the major cause of end-stage renal disease and effective and new therapeutic approaches are needed in diabetic nephropathy and chronic kidney diseases. Oxidative stress and inflammatory process are important factors contributing to kidney damage by increasing production of oxidants. KEAP1/Nrf2/ARE pathway regulates the transcription of many antioxidant genes and modulation of the pathway up regulates antioxidants. NFB controls the expression of genes involved in the inflammatory response. Natural substances have antioxidant and anti-inflammatory activities and have an impact on NFB and KEAP1/Nrf2/ARE pathways. The preclinical studies explored the effectiveness of whole herbs, plants or seeds and their active ingredients in established diabetic nephropathy. They ameliorate oxidative stress induced kidney damage, enhance antioxidant system, and decrease inflammatory process and fibrosis; most likely by activating KEAP1/Nrf2/ARE pathway and by deactivating NFB pathway. Whole natural products contain balanced antioxidants that might work synergistically to induce beneficial therapeutic outcome. In this context, more clinical studies involving whole plants or herbal products or mixtures of different herbs and plants and their active ingredients might change our strategies for the management of diabetic nephropathy. The natural products might be useful as preventive interventions and studies are required in this field.

Rice bran protein hydrolysates attenuate diabetic nephropathy in diabetic animal model

INTRODUCTION

Diabetic nephropathy (DN) is an important microvascular complication of uncontrolled diabetes. The features of DN include albuminuria, extracellular matrix alterations, and progressive renal insufficiency. Rice bran protein hydrolysates (RBPs) have been reported to have antihyperglycemic, lipid-lowering, and anti-inflammatory effects in diabetic rats. Our study was to investigate the renoprotective effects of RBP in diabetic animals and mesangial cultured cells.

METHODS

Eight-week-old male db/m and db/db mice were orally treated with tap water or RBP (100 or 500 mg/kg/day) for 8 weeks. At the end of the experiment, diabetic nephropathy in kidney tissues was investigated for histological, ultrastructural, and clinical chemistry changes, and biomarkers of angiogenesis, fibrosis, inflammation, and antioxidant in kidney were analyzed by Western blotting. Protection against proangiogenic proteins and induction of cytoprotection by RBP in cultured mesangial cells was evaluated.

RESULTS

RBP treatment improved insulin sensitivity, decreased elevated fasting serum glucose levels, and improved serum lipid levels and urinary albumin/creatinine ratios in diabetic mice. RBP ameliorated the decreases in podocyte slit pore numbers, thickening of glomerular basement membranes, and mesangial matrix expansion and suppressed elevation of MCP-1, ICAM-1, HIF-1α, VEGF, TGF-β, p-Smad2/3, and type IV collagen expression. Moreover, RBP restored suppressed antioxidant Nrf2 and HO-1 expression. In cultured mesangial cells, RBP inhibited high glucose-induced angiogenic protein expression and induced the expression of Nrf2 and HO-1.

CONCLUSION

RBP attenuates the progression of diabetic nephropathy and restored renal function by suppressing the expression of proangiogenic and profibrotic proteins, inhibiting proinflammatory mediators, and restoring the antioxidant and cytoprotective system.

Effects of ethanol extract of propolis on histopathological changes and anti-oxidant defense of kidney in a rat model for type 1 diabetes mellitus

Aims/Introduction

Oxidative stress has a key role in the pathogenesis of diabetes. Propolis and its constituents have a wide range of medicinal properties against oxidative stress. In the present study, we evaluated the anti‐oxidant effects of ethanolic extracts of propolis on kidneys in diabetes mellitus rats.

Materials and Methods

A total of 40 male Wistar rats were randomly divided into the following five groups: control, diabetes mellitus, diabetes mellitus with vehicle treatment, diabetes mellitus with propolis treatment (100 mg/kg) and diabetes mellitus with propolis treatment (200 mg/kg). Diabetes mellitus in rats was induced by intraperitoneal injection of streptozotocin (60 mg/kg). Diabetic groups were treated with vehicle or ethanolic extracts of Iranian propolis for 6 weeks. Serum concentration of malondialdehyde, superoxide dismutase and glutathione peroxidase were measured.

Results

The results showed that Iranian propolis significantly inhibited bodyweight loss in diabetes mellitus rats. The propolis extracts significantly reduced serum glucose levels and kidney weight in diabetes mellitus rats (P < 0.001). Furthermore, propolis extracts significantly reduced the malondialdehyde content, and increased the activity of superoxide dismutase and glutathione peroxidase (P < 0.001) along with the total anti‐oxidant activity in the kidney tissue of diabetes mellitus rats. In the kidneys of the diabetes mellitus and vehicle group, the glomerular basement membrane thickness and glomerular area were significantly increased. Treatment of diabetes mellitus rats with the propolis extract significantly reduced the glomerular basement membrane thickness and glomerular area.

Conclusions

The present study results showed that the Iranian propolis extract could enhance the anti‐oxidant levels and histopathological changes in the kidneys of rats. The final results showed that most of the favorable effects of propolis are mediated by a reduction of blood glucose levels in diabetic animals.

Oxidative stress markers in type 2 diabetes patients with diabetic nephropathy

BACKGROUND

Epidemiological studies show that 5-40 % of type 2 diabetes (T2DM) patients have diabetic nephropathy, and oxidative stress is one of several underlying mechanisms. We investigated associations between oxidative stress markers and severity of diabetic nephropathy.

METHODS

Fifty-nine T2DM patients from the endocrinology outpatient department were included, and their levels of oxidative stress markers were measured. Three groups were determined by their urine albumin-to-creatinine ratio (UACR): group A (UACR < 30 mg/g, n = 22); group B (30 ≤ UACR < 300 mg/g, n = 22); and group C (UACR ≥ 300 mg/g, n = 15).

RESULTS

Vitamin C levels correlated negatively and moderately with serum creatinine (γ = -0.459, p < 0.001), urine albumin (γ _s = -0.458, p = 0.001) and UACR (γ _s = -0.408, p = 0.001), but only weakly with hydroxy-2-deoxyguanosine (8-OHdG) and estimated glomerular filtration rate (eGFR). Vitamin C levels decreased as 8-OHdG, serum creatinine, albumin and UACR increased. T2DM patients with more severe diabetic nephropathy had lower vitamin C levels.

CONCLUSION

Our results identified several oxidative stress markers that may be clinically important in diabetic nephropathy. Studies with larger sample sizes should be undertaken to confirm these findings.

Ameliorative effects of pentoxifylline on NOS induced by diabetes in rat kidney

OBJECTIVES

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease worldwide. The NO system has been implicated in the pathogenesis of DN. In this study, we aimed to evaluate the healing effect of pentoxifylline on NOS in STZ-induced diabetic rat's kidney.

MATERIAL AND METHODS

In this study, 50 Wistar albino male rats were used. The rats were divided into five groups; Group C control; Group D only diabetes; Group D + PI and D + PII diabetes + pentoxifylline; Group P only pentoxifylline. Group DPI rats received just pentoxifylline from the beginning of the experiments. However, Group DPII rats received saline in the first month and 50 mg/kg/day of pentoxifylline for the following month. At the end of two months, NOS expressions in kidney tissue were assessed using qRT-PCR and immunohistochemistry analysis.

RESULTS

At the end of the experiments, desquamation of the epithelial cells of the tubules, clear glycogen-filled distal tubules and increased number of apoptotic cells were seen in Group D. Diabetic rats' nNOS immunoreactivity had increased and eNOS and iNOS immunoreactivity had decreased; nNOS, iNOS and eNOS mRNA levels tended to decrease compared to the control group. PTX ameliorated eNOS, iNOS and nNOS protein levels and apoptotic cells, but did not affect mRNA levels.

CONCLUSION

In conclusion, PTX has a healing effect on this damage by affecting NOS expression.

Immunohistochemical distribution of leptin in kidney tissues of melatonin treated diabetic rats

We examined using immunohistochemistry the distribution of leptin in kidney tissues of melatonin treated, streptozotocin (STZ) diabetic rats. The animals were divided into five groups: control, sham, melatonin-treated, diabetic and melatonin-treated diabetic. Kidney sections were prepared and stained with hematoxylin and eosin, and Crossman's triple staining for histological examination. The immunohistochemical localization of leptin in the kidney tissue was determined using the streptavidin-biotin-peroxidase method. We determined that on days 7 and 14, the leptin immunoreactivity of the diabetic and melatonin-treated diabetic groups was weaker than for the other groups. Weak immunoreactivity was found in the proximal and distal tubules of the kidney in the diabetic and melatonin-treated diabetic groups on days 7 and 14, and strong immunoreactivity was found in the control, sham and melatonin groups. Melatonin application had no significant effect on leptin production in the kidney tissues of diabetic rats.

Vitamin C in disease prevention and cure: an overview

The recognition of vitamin C is associated with a history of an unrelenting search for the cause of the ancient haemorrhagic disease scurvy. Isolated in 1928, vitamin C is essential for the development and maintenance of connective tissues. It plays an important role in bone formation, wound healing and the maintenance of healthy gums. Vitamin C plays an important role in a number of metabolic functions including the activation of the B vitamin, folic acid, the conversion of cholesterol to bile acids and the conversion of the amino acid, tryptophan, to the neurotransmitter, serotonin. It is an antioxidant that protects body from free radical damage. It is used as therapeutic agent in many diseases and disorders. Vitamin C protects the immune system, reduces the severity of allergic reactions and helps to fight off infections. However the significance and beneficial effect of vitamin C in respect to human disease such as cancer, atherosclerosis, diabetes, neurodegenerative disease and metal toxicity however remains equivocal. Thus further continuous uninterrupted efforts may open new vistas to understand its significance in disease management.

Blockade of CCL2/CCR2 signalling ameliorates diabetic nephropathy in db/db mice

BACKGROUND

CCL2/C-C chemokine receptor 2 (CCR2) signalling is suggested to play a significant role in various kidney diseases including diabetic nephropathy. We investigated the renoprotective effect of a CCR2 antagonist, RS102895, on the development of diabetic nephropathy in a type 2 diabetic mouse model.

METHODS

Six-week-old diabetic db/db and non-diabetic db/m mice were fed either normal chow or chow mixed with 2 mg/kg/day of RS102895 for 9 weeks. We investigated the effects of CCR2 antagonism on blood glucose, blood pressure, albuminuria and the structure and ultrastructure of the kidney.

RESULTS

Diabetes-induced albuminuria was significantly improved after CCR2 antagonist treatment, and glucose intolerance was improved in the RS102895-treated diabetic mice. RS102895 did not affect blood pressure, body weight or kidney weight. Mesangial expansion, glomerular basement membrane thickening and increased desmin staining in the diabetic kidney were significantly improved after RS102895 treatment. The up-regulation of vascular endothelial growth factor mRNA expression and the down-regulation of nephrin mRNA expression were markedly improved in the kidneys of RS102895-treated diabetic mice. Increased renal CD68 and arginase II and urinary malondialdehyde in diabetes were effectively attenuated by RS102895 treatment.

CONCLUSION

Blockade of CCL2/CCR2 signalling by RS102895 ameliorates diabetic nephropathy not only by improving blood glucose levels but also by preventing CCL2/CCR2 signalling from altering renal nephrin and VEGF expressions through blocking macrophage infiltration, inflammation and oxidative stress in type 2 diabetic mice.

Influence of treatment with quercetin on lipid parameters and oxidative stress of pregnant diabetic rats

Among the numerous coadjuvant therapies that could influence the incidence and progression of diabetic complications, antioxidants and flavonoids are currently being tested in clinical trials. We investigated the effect of quercetin on biochemical parameters in streptozotocin-induced (60 mg/kg body mass, by intraperitoneal injection) diabetic rats. A total of 32 female Wistar rats were distributed among 4 groups as follows: control (G1); control treated with quercetin (G2); diabetic (G3); and diabetic treated with quercetin (G4). Quercetin administered to pregnant diabetic rats controlled dyslipidemia and improved lipid profiles in diabetes mellitus, regulated oxidative stress by reducing the generation of lipid hydroperoxides, and increased the activity of the antioxidant enzyme glutathione peroxidase.

Diabetic nephropathy and antioxidants

CONTEXT

Oxidative stress has crucial role in pathogenesis of diabetic nephropathy (DN). Despite satisfactory results from antioxidant therapy in rodent, antioxidant therapy showed conflicting results in combat with DN in diabetic patients.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar,Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Treatment of DN in human are insufficient with rennin angiotensin system (RAS) blockers, so additional agent ought to combine with this management. Meanwhile based on DN pathogenesis and evidences in experimental and human researches, the antioxidants are the best candidate. New multi-property antioxidants may be improved human DN that show high power antioxidant capacity, long half-life time, high permeability to mitochondrion, improve body antioxidants enzymes activity and anti-inflammatory effects.

CONCLUSIONS

Based on this review and our studies on diabetic rats, rosmarinic acid a multi-property antioxidant may be useful in DN patients, but of course, needs to be proven in clinical trials studies.

Liquiritin attenuates advanced glycation end products-induced endothelial dysfunction via RAGE/NF-κB pathway in human umbilical vein endothelial cells

Advanced glycation end products (AGEs)-induced vasculopathy, including oxidative stress, inflammation and apoptosis responses, contributes to the high morbidity and mortality of coronary artery diseases in diabetic patients. The present study was conducted to evaluate the protective activity of liquiritin (Liq) on AGEs-induced endothelial dysfunction and explore its underlying mechanisms. After pretreatment with Liq, a significant reduction in AGEs-induced apoptosis, as well as reactive oxygen species generation and malondialdehyde level in human umbilical vein endothelial cells (HUVECs) were observed via acridine orange/ethidium bromide fluorescence staining test. Notably, Liq also significantly increased AGEs-reduced superoxide dismutase activity. Furthermore, the pretreatment with receptor for advanced glycation end products (RAGE)-antibody or Liq remarkably down-regulated TGF-beta1 and RAGE protein expressions and significantly blocked NF-κB activation which were proved by immunocytochemistry or immunofluorescence assays. These results indicated that Liq held potential for the protection on AGEs-induced endothelial dysfunction via RAGE/NF-κB pathway in HUVECs and might be a promising agent for the treatment of vasculopathy in diabetic patients.

Effects of ferulic acid on diabetic nephropathy in a rat model of type 2 diabetes

Diabetic nephropathy is the most serious complication in diabetes mellitus. It is known that oxidative stress and inflammation play a central role in the development of diabetic nephropathy. In this study, we investigated that ferulic acid (FA) known as anti-oxidative agent could effect on diabetic nephropathy by anti-oxidative and anti-inflammatory mechanism. We examined the effects of FA in obese diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats and non-diabetic control Long-Evans Tokushima Otsuka (LETO) rats. We treated FA to experimental rats from 26 to 45 weeks of age. We evaluated ACR, MDA and MCP-1 in 24 h urine and examined renal histopathology and morphologic change in extracted kidneys from rats. Also, we evaluated the ROS production and MCP-1 levels in cultured podocyte after FA treatment. In the FA-treated OLETF rats, blood glucose was significantly decreased and serum adiponectin levels were increased. Urinary ACR was significantly reduced in FA-treated OLETF rats compared with diabetic OLETF rats. In renal histopathology, FA-treated OLETF rats showed decreased glomerular basement membrane thickness, glomerular volume, and mesangial matrix expansion. FA treatment decreased oxidative stress markers and MCP-1 levels in 24 h urine of rats and supernatants of cultured podocyte. In conclusion, it was suggested that FA have protective and therapeutic effects on diabetic nephropathy by reducing oxidative stress and inflammation.

A biochemical and histopathologic study showing protection and treatment of gentamicin-induced nephrotoxicity in rabbits using vitamin C

Gentamicin and vitamin C have been proposed as nephrotoxic and antioxidant, respectively. This study involved biochemical and histopathologic investigation showing protection and treatment of gentamicin-induced nephrotoxicity in rabbits using vitamin C for 26 days hypothesizing that whether vitamin C would inhibit or decrease the raised serum urea and creatinine levels. This study was conducted on 25 healthy male albino rabbits (average weight 1.5±0.2 kg), classified into 5 groups: group A, B, C, D and E for nephrocurative (study-I) and nephroprotective (study-II) studies. Control group of rabbits (group A) received only the vehicle of gentamicin ampoule. In study-I, gentamicin sulphate (GS 80 mg/kg, i.m.) was administered to group B and C rabbits for ten days, then group C rabbits received vitamin C 250 mg/Kg for remaining 16 days. Group D and E received GS 80 mg/kg and GS 80 mg/kg i.m.-vitamin C 250 mg/kg orally, respectively during whole period (26 days) of study-II. After 26 days, various biochemical parameters, i.e. serum creatinine, blood urea nitrogen (BUN), and serum antioxidant activity, and histopathologic investigations were made. Nephrotoxicity was observed in rabbit groups B, C and D as evident from significant (p<0.05) high levels of serum creatinine and BUN and low serum antioxidant levels as compared to the levels of control group. Decrease in the levels of serum creatinine and BUN along with the increase in serum antioxidant activity was observed after vitamin C treatment in group C. While, renal-protective role of vitamin C was seen in group E as compared to the control. In conclusion, Gentamicin induced nephrotoxicity can be attenuated or treated using vitamin C.

Long-term dietary antioxidant cocktail supplementation effectively reduces renal inflammation in diabetic mice

Diabetic nephropathy is a serious complication for diabetic patients, yet the precise mechanism that underlies the development of diabetic complications remains unknown. We hypothesised that dietary antioxidant supplementation with single N-acetylcysteine (NAC) or vitamin C combined with either vitamin E or vitamin E and NAC improves diabetic renal inflammation through the modulation of blood glucose levels, oxidative stress and inflammatory response. Experimental animals were treated with alloxan monohydrate to induce diabetes. Mice were divided into five groups and supplemented with single or a combination of antioxidants. Body weights and blood glucose levels were measured once a week. After 8 weeks of dietary antioxidant supplementation, mice were killed and blood urea N (BUN) and plasma creatinine levels were measured to evaluate renal function. NF-κB protein was indirectly demonstrated by the phosphorylated IκBα (pIκBα) level, and the expressions of oxidative stress- and inflammatory response-related proteins were also determined. We demonstrated that dietary antioxidant supplementation decreased lipid peroxidation levels demonstrated by thiobarbituric acid-reacting substances, BUN and plasma creatinine levels in diabetic kidneys. Moreover, dietary antioxidant cocktail supplementation improved blood glucose levels and selectively regulated the expressions of Cu-Zn superoxide dismutase, haeme oxygenase-1, pIκBα, inducible NO synthase, cyclo-oxygenase-2 and C-reactive protein in diabetic kidneys effectively. These findings demonstrated that diabetic renal failure was associated with inflammatory responses induced by hyperglycaemia. In addition, results in the study suggest that antioxidant cocktail supplementation may have beneficial effects on diabetic nephropathy through selective reduction of blood glucose levels and inflammatory response.

Antroquinonol reduces oxidative stress by enhancing the Nrf2 signaling pathway and inhibits inflammation and sclerosis in focal segmental glomerulosclerosis mice

Oxidative stress, inflammation, and fibrosis are involved in the development and progression of focal segmental glomerulosclerosis (FSGS), a common form of idiopathic nephrotic syndrome that represents a therapeutic challenge because it has a poor response to steroids. Antroquinonol (Antroq), a purified compound, is a major active component of a mushroom, namely Antrodia camphorata, that grows in the camphor tree in Taiwan, and it has inhibitory effects on nitric oxide production and inflammatory reactions. We hypothesized that Antroq might ameliorate FSGS renal lesions by modulating the pathogenic pathways of oxidative stress, inflammation, and glomerular sclerosis in the kidney. We demonstrate that Antroq significantly (1) attenuates proteinuria, renal dysfunction, and glomerulopathy, including epithelial hyperplasia lesions and podocyte injury; (2) reduces oxidative stress, leukocyte infiltration, and expression of fibrosis-related proteins in the kidney; (3) increases renal nuclear factor E2-related factor 2 (Nrf2) and glutathione peroxidase activity; and (4) inhibits renal nuclear factor-κB (NF-κB) activation and decreases levels of transforming growth factor (TGF)-β1 in serum and kidney tissue in a mouse FSGS model. Our data suggest that Antroq might be a potential therapeutic agent for FSGS, acting by boosting Nrf2 activation and suppressing NF-κB-dependent inflammatory and TGF-β1-mediated fibrosis pathways in the kidney.

Effects of grape seed proanthocyanidin extract on oxidative stress induced by diabetes in rat kidney

BACKGROUND

This study examined the effect of grape seed proanthocyanidin extract (GSPE) on lipid peroxidation content and activity of tissue antioxidant enzymes, including catalase, superoxide dismutase and glutathione peroxidase in diabetic rats.

METHODS

Thirty male rats were divided into three groups of 10 rats each: control, diabetic and diabetic groups that received 500 mg/kg GSPE for 6 weeks. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg/kg body weight). Rats with fasting blood glucose levels above 250 mg/dl were used as diabetic animals. The first 24-hour urinary albumin excretion (UAE) was measured two weeks after diabetes induction and then each week until the end of the experimental period in all groups. Lipid peroxidation content and activities of catalase, superoxide dismutase and glutathione peroxidase were measured in kidney homogenate supernatants. Statistical significance of differences was assessed with one-way ANOVA by SPSS followed by Tukey's t-test. P < 0.05 was assumed statistically significant.

RESULTS

UAE in diabetic nephropathy rats were significantly higher than in control. In addition, an increase in lipid peroxidation content and decrease in catalase, superoxide dismutase and glutathione peroxidase activities in kidney of diabetic nephropathy rats were observed. The GSPE administration did not affect on body weight, but significantly decreased lipid peroxidation and augmented the activities of antioxidant enzymes studied in kidney of diabetic nephropathy rats as well as reduced UAE and decreased kidney weight.

CONCLUSION

The results suggested that GSPE could ameliorate diabetic nephropathy rats through reduction of oxidative stress and increase in renal antioxidant enzyme activity.

Satureja khozestanica essential oil ameliorates progression of diabetic nephropathy in uninephrectomized diabetic rats

Diabetic nephropathy is the common cause of leading to end stage of renal disease (ESRD). Satureja khozestanica essential oil (SKEO) was used as an antioxidant and antidiabetic for the inhibition of diabetic nephropathy. Forty male rats were uninephrectomized and divided in four groups randomly; group one as control, group two diabetic untreatment, groups three and four treatment with SKEO by 250 or 500 ppm in drinking water, respectively. Diabetes was induced in the second, third and fourth groups by alloxan injection subcutaneously. After eight weeks treatment, serum malondialdehyde, serum creatinine and serum urea were measured. The kidney paraffin sections were stained by periodic acid Schiff method. Glomerular volume and glomerular number were estimated by stereological rules. Glomerular sclerosis was studied semi-quantitatively. The means were compared by SPSS 13 software and Mann-Whitney test at p<0.05. Satureja khozestanica essential oil (250 or 500 ppm) significantly inhibited the progression of glomerular hypertrophy, glomerular number loss, glomerulosclerosis, lipid peroxidation, serum urea and creatinine compared with the diabetic untreated group. The level of glomerular number, serum malondialdehyde, serum creatinine and urea in the treated groups was significantly maintained at the same level as that of the control group. In conclusion, satureja essential oil significantly can ameliorate glomerular hypertrophy, loss of glomerular number, glomerulosclerosis and attenuated serum urea and serum creatinine in diabetic rats.

The role of reactive oxygen species in apoptosis of the diabetic kidney

Increased levels of reactive oxygen species (ROS) by hyperglycemia can induce apoptosis of renal cells and diabetic nephropathy. The redox balance in the renal cell seems, therefore, of the utmost importance. ROS-mediated apoptosis may be further aggravated by an inadequate cytoprotective response against ROS. When there are insufficient cytoprotective and ROS scavenging molecules, ROS lead to considerable cellular damage and to a point of no return in apoptosis. Induction of cytoprotective proteins may prevent or attenuate apoptosis, renal cell injury, and finally diabetic nephropathy. Here, we discuss some mechanisms of apoptosis and several strategies that have been probed to ameliorate, or to prevent apoptosis in the diabetic kidney.