Reactive Oxygen Species In Kidney Research Articles

Urinary Angiotensinogen Displays Sexual Dimorphism in Non-Diabetic Humans and Mice with Overweight.

Increased body weight (BW) induces inappropriate renin-angiotensin system (RAS) activation. The activation of the intrarenal RAS is associated with increased urinary angiotensinogen (uAGT), blood pressure (BP), and kidney damage. Here, we examined uAGT excretion levels in young non-diabetic human subjects with overweight (OW) and non-diabetic mice with high-fat diet (HFD)-induced OW. Human subjects (women and men; 20-28 years old) included two groups: (a) overweight (OW, n = 17, BMI ≥ 25); and (b) controls (normal weight (NW; n = 26, BMI ≤ 25). In these subjects, we measured BP, albuminuria, and protein levels of uAGT by ELISA adjusted by urinary creatinine (expressed by uAGT/uCrea). Mice (female and male C57BL/6J mice, 8 ± 2 weeks of age) also included two groups: HFD or normal fat diet (NFD) fed for 8 weeks. We measured BW, fasting blood glucose (FBG), BP by telemetry, albuminuria, and uAGT by ELISA. In humans: (i) no significant changes were observed in BP, albuminuria, and FBG when comparing NW and OW subjects; (ii) multivariate logistic regression analysis of independent predictors related to uAGT/uCrea levels demonstrated a strong association between uAGT and overweight; (iii) urinary reactive oxygen species (ROS) were augmented in men and women with OW; (iv) the uAGT/uCrea ratio was higher in men with OW. However, the uAGT/uCrea values were lower in women even with OW. In mice: (i) males fed an HFD for 8 weeks became OW while females did not; (ii) no changes were observed either in FBG, BP, or albuminuria; (iii) kidney ROS were augmented in OW male mice after 28 weeks but not in females; (iv) OW male mice showed augmented excretion of uAGT but this was undetectable in females fed either NFD or HFD. In humans and mice who are OW, the urinary excretion of AGT differs between males and females and overcomes overt albuminuria.

Zuogui Wan ameliorates high glucose-induced podocyte apoptosis and improves diabetic nephropathy in db/db mice.

Zuogui Wan (ZGW), a well-known traditional Chinese medicine (TCM), has been used to nourish "Kidney-Yin" for a long time in China, implying a protective effect on the kidney. The aim of the present study is to investigate the effect of ZGW on high glucose-induced podocyte apoptosis and diabetic nephropathy (DN) in db/db mice. ZGW (1g/kg-1/day-1) was administered intragastrically to db/db mice for 8weeks. HPLC was used for identifying the components of ZGW, biochemical and histopathological approaches were used for evaluating its therapeutic effects, and cultured mouse podocytes were used for further exploring its underlying mechanism in vitro. ZGW improved renal function and podocyte loss and also normalized kidney reactive oxygen species production in db/db mice. The cytotoxicity of ZGW on mouse podocytes was assessed by the LDH assay. The effect of ZGW on podocyte viability and apoptosis was determined with CCK-8 and Annexin-V/PI staining by treatment with high glucose. ZGW attenuated podocyte apoptosis, and oxidative stress was detected by the peroxide-sensitive fluorescent probe 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA) staining in a dose-dependent manner. Furthermore, ZGW decreased the expression of caspase-3 and phospho-p38 in both the kidney cortex and high glucose-treated podocytes. Thus, our data from in vivo and in vitro studies demonstrated that ZGW improved renal injury in diabetes by inhibiting oxidative stress and podocyte apoptosis.

In Vitro and In Vivo Evidence on the Role of Mitochondrial Impairment as a Mechanism of Lithium-Induced Nephrotoxicity.

Lithium is abundantly administered against bipolar disorder. On the other hand, the lithium-induced renal injury is a clinical complication which commonly reveals as drug-induced diabetes insipidus. However, lithium-induced cytotoxicity might also play a role in the adverse effects of this drug on the kidney. There is no clear cellular and molecular mechanism(s) for lithium-induced nephrotoxicity. The current study was designed to assess the effect of lithium on kidney tissue oxidative stress biomarkers and mitochondrial function and its relevance to drug-induced nephrotoxicity and electrolyte imbalance. Rats were treated with lithium (lithium carbonate, 25 and 50mg/kg/day, i.p., for 28 consecutive days). Kidney mitochondria were also isolated from rats and exposed to increasing concentrations of lithium (0.01-10mM). Serum and urine biomarkers of kidney injury, kidney tissue markers of oxidative stress, and renal histopathological changes were assessed. Moreover, several mitochondrial indices were monitored. Lithium-induced renal injury revealed a significant increase in urine and serum biomarkers of renal impairment. Lithium caused an increase in the kidney reactive oxygen species (ROS) level and lipid peroxidation (LPO). Renal glutathione (GSH) reservoirs were also depleted, and tissue antioxidant capacity decreased in lithium-treated animals. Significant tissue histopathological changes, including necrosis, Bowman capsule dilation, and interstitial inflammation, were evident in lithium-treated animals. On the other hand, significant alterations in kidney mitochondrial function were detected in lithium-treated groups. These data mention oxidative stress, mitochondrial dysfunction, and cellular energy crisis as the potential primary mechanisms for lithium-induced renal injury.

The Nephroprotective Role of Carnosine Against Ifosfamide-Induced Renal Injury and Electrolytes Imbalance is Mediated Via the Regulation of Mitochondrial Function and Alleviation of Oxidative Stress.

Ifosfamide (IFO) is an alkylating agent administered against different types of malignancies. Several cases of renal injury and serum electrolytes disturbances have been reported in IFO-treated patients. Oxidative stress and mitochondrial dysfunction are suspected of being involved in the mechanism of IFO nephrotoxicity. Carnosine is a dipeptide which its antioxidant and mitochondria protecting properties have been mentioned in different experimental models. The current study aimed to evaluate the nephroprotective properties of carnosine against IFO-induced renal injury. Rats were treated with IFO (50 mg/kg, i.p) alone or in combination with carnosine. Serum and urine biomarkers of renal injury in addition to kidney markers of oxidative stress were evaluated. Moreover, kidney mitochondria were isolated, and some mitochondrial indices were assessed. Elevated serum creatinine and BUN, hypokalemia, and hypophosphatemia, in addition, to an increase in urine glucose, protein, γ-GT, and alkaline phosphatase (ALP), were evident in IFO-treated animals. IFO also caused an increase in kidney reactive oxygen species (ROS) and lipid peroxidation (LPO). Renal GSH levels and antioxidant capacity were also depleted with IFO therapy. Mitochondrial dehydrogenase activity, GSH level, membrane potential, and ATP content were decreased while mitochondrial LPO and permeabilization were increased in IFO group. Carnosine (250 and 500 mg/kg, i.p) mitigated IFO-induced oxidative stress and mitochondrial impairment in renal tissue. Our data suggest mitochondrial dysfunction and oxidative stress as fundamental mechanisms of renal injury induced by IFO. On the other hand, carnosine supplementation protected kidneys against IFO-induced injury through regulating mitochondrial function and mitigating oxidative stress.

The nephroprotective properties of taurine in colistin-treated mice is mediated through the regulation of mitochondrial function and mitigation of oxidative stress

Colistin (COL) belongs to the polymixin class of antibiotics used as the last line antibiotic against drug-resistant infections. However, nephrotoxicity is the major deleterious and dose-limiting side effect associated with COL therapy. Oxidative stress and mitochondrial impairment are suspected mechanisms involved in COL-induced nephrotoxicity. Taurine is one of the most abundant amino acids in the human body with antioxidant and mitochondria protecting properties. The current study was designed to evaluate the potential nephroprotective properties of taurine against COL-associated nephrotoxicity. Mice were treated with COL (15 mg/kg/day, i.v, for 7 consecutive days) alone or in combination with taurine (500 and 1000 mg/kg, i.p). Plasma biomarkers of nephrotoxicity in addition of kidney tissue markers of oxidative stress were evaluated. Additionally, kidney mitochondria were isolated, and several mitochondrial indices were assessed. The COL-associated renal injury was evident by a significant increase in plasma markers of renal injury including creatinine (Cr), and blood urine nitrogen (BUN). COL treatment also caused a significant increase in kidney reactive oxygen species (ROS) and lipid peroxidation (LPO). Renal GSH reservoirs and antioxidant capacity were also decreased in COL-treated animals. Mitochondrial parameters including mitochondrial dehydrogenase activity, membrane potential, GSH, and ATP were significantly decreased while mitochondrial LPO, permeabilization, and GSSG content were increased in the kidney of COL-treated mice. It was found that taurine (500 and 1000 mg/kg, i.p) treatment alleviated COL-induced oxidative stress and mitochondrial dysfunction in the kidney tissue. The data obtained from the current study suggest mitochondrial dysfunction and oxidative stress as fundamental mechanisms of renal injury induced by COL. On the other hand, taurine supplementation protected kidney through decreasing oxidative stress and regulating mitochondrial function.

Daphnetin protects against cisplatin-induced nephrotoxicity by inhibiting inflammatory and oxidative response

Daphnetin, one of the major bioactive components isolated from Daphne odora, has been reported to have anti-inflammatory and anti-oxidative effects. Inflammation and oxidative stress have been known to play critical roles in cisplatin-induced nephrotoxicity. The purpose of this study was to investigate the protective effects of daphnetin on cisplatin-induced nephrotoxicity. The levels of blood urea nitrogen (BUN) and creatinine, as well as the kidney reactive oxygen species (ROS), and malondialdehyde (MDA) activity were measured in this study. The expression of inflammatory cytokines TNF-α and IL-1β were measured by ELISA. The results showed that daphnetin protected against cisplatin-induced nephrotoxicity by attenuating kidney histological changes, serum BUN and creatinine. Furthermore, the expression of TNF-α and IL-1β, as well as ROS and MDA in kidney tissues were decreased by daphnetin. In addition, daphnetin dose-dependently inhibited cisplatin-induced NF-κB activation and up-regulated the expression of Nrf2 and HO-1. In conclusion, the results of this study suggested that daphnetin inhibited cisplatin-induced nephrotoxicity by inhibiting NF-κB and activating Nrf2 signaling pathways. Daphnetin might be a promising agent in the treatment of kidney injury.

Mitochondrial dysfunction and oxidative stress are involved in the mechanism of methotrexate-induced renal injury and electrolytes imbalance

Methotrexate is a folate analog used against a wide range of diseases including malignancies and autoimmune disorders. On the other hand, clinical use of the MTX is associated with kidney injury and renal failure. There is no clear mechanism for MTX-induced renal injury. The current investigation was designed to evaluate the role of mitochondrial dysfunction and oxidative stress in the pathogenesis of MTX-induced renal injury. Rats received MTX (a single dose of 20 or 30 mg/kg, i.p). Five days after MTX administration, serum biomarkers of kidney injury and tissue markers of oxidative stress were assessed. Moreover, kidney mitochondria were isolated, and several mitochondrial indices were determined. MTX-treated animals developed biochemical evidence of renal injury as judged by elevated serum blood urea nitrogen (BUN), creatinine (Cr) and along with hypokalemia, hypophosphatemia, hypocalcemia, and a decrease in serum glucose, and uric acid. Moreover, MTX caused an increase in kidney reactive oxygen species and lipid peroxidation. Renal glutathione reservoirs were also depleted, and tissue antioxidant capacity was decreased in MTX-treated animals. Kidney histopathological changes including interstitial inflammation, renal tubular degeneration, retraction glomeruli, and vascular congestion were also evident in MTX-treated rats. On the other hand, it was found that mitochondrial parameters including mitochondrial membrane potential, mitochondrial dehydrogenases activity, and mitochondrial glutathione and ATP content were decreased, while lipid peroxidation and mitochondrial permeabilization were increased with MTX treatment. These data suggest a role for mitochondrial dysfunction and oxidative stress in the mechanism of MTX nephrotoxicity.

Quercetin-Rich Guava (Psidium guajava) Juice in Combination with Trehalose Reduces Autophagy, Apoptosis and Pyroptosis Formation in the Kidney and Pancreas of Type II Diabetic Rats.

We explored whether the combination of anti-oxidant and anti-inflammatory guava (Psidium guajava) and trehalose treatment protects the kidney and pancreas against Type II diabetes (T2DM)-induced injury in rats. We measured the active component of guava juice by HPLC analysis. T2DM was induced in Wistar rats by intraperitoneal administration of nicotinamide and streptozotocin and combination with high fructose diets for 8 weeks. The rats fed with different dosages of guava juice in combination with or without trehalose for 4 weeks were evaluated the parameters including OGTT, plasma insulin, HbA1c, HOMA-IR (insulin resistance) and HOMA-β (β cell function and insulin secretion). We measured oxidative and inflammatory degrees by immunohistochemistry stain, fluorescent stain, and western blot and serum and kidney reactive oxygen species (ROS) by a chemiluminescence analyzer. High content of quercetin in the guava juice scavenged H2O2 and HOCl, whereas trehalose selectively reduced H2O2, not HOCl. T2DM affected the levels in OGTT, plasma insulin, HbA1c, HOMA-IR and HOMA-β, whereas these T2DM-altered parameters, except HbA1c, were significantly improved by guava and trehalose treatment. The levels of T2DM-enhanced renal ROS, 4-hydroxynonenal, caspase-3/apoptosis, LC3-B/autophagy and IL-1β/pyroptosis were significantly decreased by guava juice and trehalose. The combination with trehalose and guava juice protects the pancreas and kidney against T2DM-induced injury.

Effect of NADPH oxidase inhibitor apocynin on the exercise induced proteinuria in rats

To investigate the effect of NADPH oxidase inhibitor apocynin on exercise-induced proteinuria and its related mechanism. Thirty-two SD rats were randomly divided into the control group (group C), control + drug group (group CA), exhaustive exercise group (group E), exhaustive exercise + drug group (group EA). The rats were administrated apocynin at 10 mg/kg weight,once a day for three days, and one hour after the drug injection, a one-time exhaustive exercise was performed. After exhaustive exercise, urine protein, blood urea nitrogen (BUN), and kidney reactive oxygen species (ROS) concentration, NOS activity, NOS and 3-NT concentration were detected. In comparison to control group urinary protein (UP), ROS, inductible nitric oxide synthase (iNOS), 3-NT levels increased significantly in group E while those in group EA did not change. The elevated renal NADPH oxidase activity by exhaustive exercise induced ROS that can rapidly react with NO, and then produces excess peroxynitrite, which contributes to occurrence of exercise-induced proteinuria.

Pretreatment of Sialic Acid Efficiently Prevents Lipopolysaccharide-Induced Acute Renal Failure and Suppresses TLR4/gp91-Mediated Apoptotic Signaling

Background/Aims: Lipopolysaccharides (LPS) binding to Toll-like receptor 4 (TLR4) activate NADPH oxidase gp91 subunit-mediated inflammation and oxidative damage. Recognizing the high binding affinity of sialic acid (SA) with LPS, we further explored the preventive potential of SA pretreatment on LPS-evoked acute renal failure (ARF). Methods: We determined the effect of intravenous SA 30 min before LPS-induced injury in urethane-anesthetized female Wistar rats by evaluating kidney reactive oxygen species (ROS) responses, renal and systemic hemodynamics, renal function, histopathology, and molecular mechanisms. Results: LPS time-dependently reduced arterial blood pressure, renal microcirculation, and increased blood urea nitrogen and creatinine in the rats. LPS enhanced monocyte/macrophage infiltration and ROS production, and subsequently impaired kidneys with the enhancement of TLR4/NADPH oxidase gp91/Caspase 3/poly-(ADP-ribose)-polymerase (PARP)-mediated apoptosis in the kidneys. SA pretreatment effectively alleviated LPS-induced ARF. The levels of LPS-increased ED-1 infiltration and ROS production in the kidney were significantly depressed by SA pretreatment. Furthermore, SA pretreatment significantly depressed TLR4 activation, gp91 expression, and Caspase 3/PARP induced apoptosis in the kidneys. Conclusion: We suggest that pretreatment of SA significantly and preventively attenuated LPS-induced detrimental effects on systemic and renal hemodynamics, renal ROS production and renal function, as well as, LPS-activated TLR4/gp91/Caspase3 mediated apoptosis signaling.

ERK1/2 pathway is involved in renal gluconeogenesis inhibition under conditions of lowered NADPH oxidase activity

The aim of this study was to elucidate the mechanisms involved in the inhibition of renal gluconeogenesis occurring under conditions of lowered activity of NADPH oxidase (Nox), the enzyme considered to be one of the main sources of reactive oxygen species in kidneys. The in vitro experiments were performed on primary cultures of rat renal proximal tubules, with the use of apocynin, a selective Nox inhibitor, and TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a potent superoxide radical scavenger. In the in vivo experiments, Zucker diabetic fatty (ZDF) rats, a well established model of diabetes type 2, were treated with apocynin solution in drinking water. The main in vitro findings are the following: (1) both apocynin and TEMPOL attenuate the rate of gluconeogenesis, inhibiting the step catalyzed by phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme of the process; (2) in the presence of the above-noted compounds the expression of PEPCK and the phosphorylation of transcription factor CREB and ERK1/2 kinases are lowered; (3) both U0126 (MEK inhibitor) and 3-(2-aminoethyl)-5-((4-ethoxyphenyl)methylene)-2,4-thiazolidinedione (ERK inhibitor) diminish the rate of glucose synthesis via mechanisms similar to those of apocynin and TEMPOL. The observed apocynin in vivo effects include: (1) slight attenuation of hyperglycemia; (2) inhibition of renal gluconeogenesis; (3) a decrease in renal PEPCK activity and content. In view of the results summarized above, it can be concluded that: (1) the lowered activity of the ERK1/2 pathway is of importance for the inhibition of renal gluconeogenesis found under conditions of lowered superoxide radical production by Nox; (2) the mechanism of this phenomenon includes decreased PEPCK expression, resulting from diminished activity of transcription factor CREB; (3) apocynin-evoked inhibition of renal gluconeogenesis contributes to the hypoglycemic action of this compound observed in diabetic animals. Thus, the study has delivered some new insights into the recently discussed issue of the usefulness of Nox inhibition as a potential antidiabetic strategy.

Activation of the NLRP3 Inflammasome in Association with Calcium Oxalate Crystal Induced Reactive Oxygen Species in Kidneys

We investigated the association of hyperoxaluria and calcium oxalate crystal induced production of reactive oxygen species with activation of the NLRP3 inflammasome. Eight-week-old male rats were given hydroxy-L-proline to induce hyperoxaluria. A group of rats on the hydroxy-L-proline diet also received apocynin, an antioxidant and nonspecific inhibitor of NADPH oxidase. At 28 days the rats were sacrificed and the kidneys were extracted. Microarray analysis was done with the BeadArray™ Reader. Gene ontology and gene pathway analyses were done with the DAVID (Database for Annotation, Visualization of Integrated Discovery) enrichment analysis tool. Quantitative real-time polymerase chain reaction and immunohistochemical staining were performed to confirm microarray results. Analysis of 22,226 genes revealed that 20 and 24 pathways were highly significant in the cortex and medulla, respectively. In the cortex extracellular matrix-receptor interaction, complement and coagulation cascades, focal adhesion and hypertrophic cardiomyopathy were the most significant pathways. In the medulla complement and coagulation cascades, extracellular matrix-receptor interaction and dilated cardiomyopathy were the major pathways. Genes encoding for PYCARD (ASC), TXNIP, NLRP3, caspase-1, and IL-1β and 18 were significantly up-regulated in hydroxy-L-proline fed rats but in the group that received apocynin these genes were down-regulated in the cortex and medulla. Results were verified by quantitative real-time polymerase chain reaction with SYBR® Green assay and immunohistochemical staining. Results indicate a role for reactive oxygen species in activation of the NLRP3 inflammasome via TXNIP. This led to a robust inflammatory response in the kidneys of rats with hyperoxaluria and calcium oxalate nephrolithiasis.

Sialic acid rescues repurified lipopolysaccharide-induced acute renal failure via inhibiting TLR4/PKC/gp91-mediated endoplasmic reticulum stress, apoptosis, autophagy, and pyroptosis signaling.

Lipopolysaccharides (LPS) through Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4) activation induce systemic inflammation where oxidative damage plays a key role in multiple organ failure. Because of the neutralization of LPS toxicity by sialic acid (SA), we determined its effect and mechanisms on repurified LPS (rLPS)-evoked acute renal failure. We assessed the effect of intravenous SA (10 mg/kg body weight) on rLPS-induced renal injury in female Wistar rats by evaluating blood and kidney reactive oxygen species (ROS) responses, renal and systemic hemodynamics, renal function, histopathology, and molecular mechanisms. SA can interact with rLPS through a high binding affinity. rLPS dose- and time-dependently reduced arterial blood pressure, renal microcirculation and blood flow, and increased vascular resistance in the rats. rLPS enhanced monocyte/macrophage (ED-1) infiltration and ROS production and impaired kidneys by triggering p-IRE1α/p-JNK/CHOP/GRP78/ATF4-mediated endoplasmic reticulum (ER) stress, Bax/PARP-mediated apoptosis, Beclin-1/Atg5-Atg12/LC3-II-mediated autophagy, and caspase 1/IL-1β-mediated pyroptosis in the kidneys. SA treatment at 30 min, but not 60 min after rLPS stimulation, gp91 siRNA and protein kinase C-α (PKC) inhibitor efficiently rescued rLPS-induced acute renal failure via inhibition of TLR4/PKC/NADPH oxidase gp91-mediated ER stress, apoptosis, autophagy and pyroptosis in renal proximal tubular cells, and rat kidneys. In response to rLPS or IFNγ, the enhanced Atg5, FADD, LC3-II, and PARP expression can be inhibited by Atg5 siRNA. Albumin (10 mg/kg body weight) did not rescue rLPS-induced injury. In conclusion, early treatment (within 30 min) of SA attenuates rLPS-induced renal failure via the reduction in LPS toxicity and subsequently inhibiting rLPS-activated TLR4/PKC/gp91/ER stress/apoptosis/autophagy/pyroptosis signaling.

Celecoxib modulates nitric oxide and reactive oxygen species in kidney ischemia/reperfusion injury and rat aorta model of hypoxia/reoxygenation

ObjectiveThis study investigated the interaction between COX-2, NO and ROS after ischemia/reperfusion events in the kidney and vascular beds. Materials and methodsKidney IRI model in male Sprague–Dawley rats was used and various biochemical and histopathological parameters were examined. The isolated rat aortic rings served as model for hypoxia/reoxygenation. ResultsCelecoxib reduced serum creatinine and urea and kidney malonaldehyde levels, increased kidney superoxide dismutase activity and reduced glutathione level and histopathological scores at 24 and 48h after reperfusion compared to IRI group. This was associated with a significant increase in NO level to 0.70±0.03nmol/mg protein compared to 0.37±0.01nmol/mg protein for IRI group. Unexpectedly, celecoxib reduced COX-2 expression in the kidney. Celecoxib reversed the effect of hypoxia–reoxygenation on ACh and SNP-induced relaxation in aortic rings but failed to potentiate the SNP relaxations in the control rings. Hypoxia–reoxygenation significantly impaired celecoxib’s relaxation of aorta (12.69±2.69% vs. 35.84 ±0.84%) which was significantly inhibited in presence of L-NAME. ConclusionsCelecoxib beneficially affects the outcome of renal IRI by lowering the expression of COX-2 and hence reducing oxidative stress and increasing the bioavailability of NO. Direct interaction between celecoxib and NO in associated vascular beds may also be a contributing mechanism.

NOX1 abet mesangial fibrogenesis via iNOS induction in diabetes

Both NADPH oxidase (NOX) and inducible nitric oxide synthase (iNOS) are the main sources of reactive oxygen species in kidney. However, their interactions in oxidative stress and contributions to kidney fibrosis during diabetic nephropathy have not been studied. Human mesangial cells were treated with normal glucose (5.6 mmol/L), high glucose (30 mmol/L) in the presence or absence of AGE (200 mg/L). Protein expressions of NOX1, NOX2, NOX4, and iNOS were examined by immunoblotting. NOX was genetically silenced with specific RNAi to study the interactions between NOX and iNOS in diabetic milieu. Superoxide (O(·-)) and peroxynitrite (ONOO(·-)) productions were assessed by dihydroethidium and hydroxyphenyl fluorescein, respectively. Fibrotic factors were determined by biochemistry assay. Superoxide, peroxynitrite, TGF-β, and fibronectin productions as well as the protein expressions of NOX1, NOX2, NOX4, and iNOS were increased in the diabetic milieu (high glucose 30 mmol/L plus AGE 200 mg/L). However, abolishment of iNOS induction with 1400W or iNOS RNAi would restore peroxynitrite, TGF-β, and fibronectin productions completely to basal level and attenuate superoxide production. Moreover, NOX1 inhibition not only prevented iNOS induction but also abrogated changes consequent to iNOS induction such as mesangial fibrogenesis.

Abstract 371: Nitrosonifedipine, a Photodegradation Product of Nifedipine, Prevents the Progression of Diabetic Nephropathy in Type II Diabetic Mice

Diabetic nephropathy (DN) is a major microvascular complication of diabetes involving oxidative stress and endothelial damage. Nitrosonifedipine (NO-NIF) is converted from nifedipine under the light illumination. The ability of NO-NIF to block calcium channels is quite weak compared with that of nifedipine. Recently, we have demonstrated that NO-NIF reacts with unsaturated fatty acid leading to generate NO-NIF radical, which acquires radical scavenging activity. Also we have reported that NO-NIF reduces cytotoxicity of tumor necrosis factor-α (TNF-α) in cultured human glomerular endothelial cells. However, it is unclear the effects of NO-NIF on the pathogenesis related with oxidative stress, such as DN. In this study, we investigated whether NO-NIF treatment improves DN by using KKAy mice developing type II diabetes. Urinary albumin (UA) and total urinary protein (TUP) were elevated in KKAy mice (16 weeks old) compared with C57BL/6 mice, which were significantly decreased by NO-NIF treatment (30 mg/kg/day, i.p., 4 weeks) (UA; 1415.2 ± 312.5 vs 609.6 ± 151.5 μg/24hr, p<0.05, TUP; 73.1 ± 11.2 vs 44.8 ± 9.4 mg/24hr, p<0.05). Mesangial expansion was estimated by PAS staining. Glomerular diameter (GD) and glomerular tuft area (GTA) were extended in KKAy mice compared with C57BL/6 mice, which were significantly decreased by NO-NIF treatment (GD; 81.4 ± 2.6 vs 65.7 ± 1.9 μm, p<0.05, GTA; 4198.8 ± 254.6 vs 3051.9 ± 140.4 μm2, p<0.05). NO-NIF significantly suppressed urinary 8-hydroxy-20-deoxyguanosine (144.1 ± 21.4 vs 75.2 ± 11.1 ng/24hr, p<0.05) in KKAy mice. Also NO-NIF reduced the elevation of reactive oxygen species in kidney of KKAy mice detected by DHE staining. However NO-NIF had no influence on SOD activity in kidney. NO-NIF significantly inhibited the mRNA expression of TNF-α in kidney of KKAy mice (2.9 ± 0.1 vs 1.9 ± 0.1 fold increase, p<0.05). ICAM-1 protein expression was increased in glomeruli of KKAy mice, which was decreased by NO-NIF treatment. On the other hand, NO-NIF had no effect on glucose tolerance and systolic blood pressure (111.1 ± 2.3 vs 108.3 ± 3.3 mmHg, N.S.) in KKAy mice. These findings suggest that NO-NIF prevents the progression of DN via the attenuation of oxidative stress independent of antihypertensive or antihyperglycemic action.

Co‐administration of meso 2,3‐dimercaptosuccinic acid monoesters reduces arsenic concentration and oxidative stress in gallium arsenide exposed rats

1. Gallium arsenide (GaAs), a semiconductor, exerts toxicity as a result of its constitutive moieties; that is, gallium and arsenic that becomes dissociated after exposure. The present study focuses on reducing arsenic concentration from the target organs using monoesters of meso 2,3-dimercaptosuccinic acid (DMSA) either individually or in combination. 2. Animals were exposed to GaAs (0.0014 mol/kg, orally for 8 weeks) and then treated with monoisoamyl DMSA (MiADMSA), monocyclohexyl DMSA (MchDMSA) or monomethyl DMSA (MmDMSA) either individually (0.3 mmol/kg, orally) or in combination (0.15 mmol/kg each, orally) for five consecutive days. 3. GaAs exposure significantly inhibited blood δ-aminolevulinic acid dehydrogenase (ALAD), suggesting alterations in the heme synthesis pathway. Whereas a significant increase in blood, liver and kidney reactive oxygen species accompanied by an increase in lipid peroxidation points to the involvement of oxidative stress in GaAs toxicity. 4. GaAs also significantly disturbed glutathione metabolism. Hepatic and renal catalase activity decreased significantly, whereas hepatic and renal superoxide dismutase activity, as well as serum transaminases activity, showed marginal increase. Treatment with MiADMSA in combination with MchDMSA showed better therapeutic efficacy compared with other treatments in the aforementioned variables. 5. Co-administration of MiADMSA with MchDMSA provided better therapeutic effects, including reduction of arsenic burden, compared with all other treatments.

Protective effects of an aqueous extract from pepino (Solanum muricatumAit.) in diabetic mice

This study analysed the content of ascorbic acid, phenolic acids and flavonoids in aqueous and ethanol extracts of pepino (Solanum muricatum Ait.), and examined the protective effects of pepino aqueous extract (PAE) in a mouse model of diabetes. PAE at 1, 2 and 4% was supplied for 5 weeks. Aqueous and ethanol extracts had similar levels of total phenolic acids, but PAE had a higher content of ascorbic acid and total flavonoids than the ethanol extract. PAE treatments at 2% and 4% significantly lowered plasma glucose level (P < 0.05); however, only the 4% PAE significantly elevated plasma insulin level at week 5 (P < 0.05). PAE treatments significantly decreased the levels of malonyldialdehyde and reactive oxygen species in kidney (P < 0.05); however, only the 2% and 4% treatments significantly reduced oxidised glutathione formation, increased glutathione level, and retained renal glutathione peroxidase and catalase activities (P < 0.05). PAE treatments at 2% and 4% significantly lowered renal interleukin (IL)-6 and tumour necrosis factor-α levels (P < 0.05); however, only the 4% treatments significantly diminished renal IL-1β and levels of monocyte chemoattractant protein-1 (P < 0.05). PAE treatments at 4% significantly decreased aldose reductase activity and sorbitol production in kidney (P < 0.05). These findings support the suggestion that pepino aqueous extract could attenuate the progression of diabetes via its antioxidative, anti-inflammatory and antiglycative effects.

Inhibition of renal gluconeogenesis contributes to hypoglycaemic action of NADPH oxidase inhibitor, apocynin

NADPH oxidase, catalysing superoxide radical (O2−) formation, is considered as a main source of reactive oxygen species in kidneys and its increased activity is supposed to be involved in the development of diabetic nephropathy. The aim of this study was to investigate the effect of NADPH oxidase inhibitor, apocynin, on renal gluconeogenesis, which is an important source of endogenous glucose under diabetic conditions.The following observations were made during the experiments performed on isolated renal proximal tubules of control and alloxan diabetic rabbits: (1) apocynin (200μM) inhibited the rate of glucose synthesis by 45–80%, depending on the substrate applied; (2) the rate of glucose production was also significantly diminished in the presence of TEMPOL (5mM), a superoxide radical scavenger, suggesting that the decrease in O2− formation might be involved in apocynin-evoked gluconeogenesis inhibition; (3) the activities of phosphoenolpyruvate carboxykinase (PEPCK) and/or aldolase were lowered in the presence of either apocynin or TEMPOL, as concluded from the intracellular levels of gluconeogenic intermediates. The data from in vivo experiments indicated that apocynin treatment (2g/l of drinking water): (1) significantly (by about 30%) attenuated serum glucose concentration in diabetic rabbits and did not affect glycaemia in control animals; (2) normalized diabetes-stimulated rate of glucose synthesis and slightly inhibited gluconeogenesis in control rabbits; (3) normalized diabetes-increased activity of mitochondrial PEPCK and lowered cytosolic PEPCK activity by about 20% below the value for untreated control animals; (4) slightly decreased the activity of mitochondrial PEPCK and did not change the activity of cytosolic one in control rabbits.Thus, it is concluded that: (1) the inhibition of NADPH oxidase might contribute to lowered rate of renal gluconeogenesis, probably due to decreasing PEPCK activity; (2) inhibition of renal gluconeogenesis is involved in apocynin hypoglycaemic action in vivo; (3) apocynin might be beneficial for diabetes treatment.

Kidney expression of glutathione peroxidase-1 is not protective against streptozotocin-induced diabetic nephropathy

In many diseases, including progressive renal disorders, tissue injury and pathological intracellular signaling events are dependent on oxidative stress. Glutathione peroxidase-1 (Gpx1) is an antioxidant enzyme that is highly expressed in the kidney and removes peroxides and peroxynitrite that can cause renal damage. Therefore, we examined whether this abundant renal antioxidant enzyme limits renal damage during the development of type 1 diabetic nephropathy. Wild-type (Gpx1+/+) and deficient (Gpx1-/-) mice were made diabetic by intraperitoneal injection of streptozotocin (100 mg/kg) on 2 consecutive days. Diabetic Gpx1+/+ and -/- mice with equivalent blood glucose levels (23 +/- 4 mM) were selected and examined after 4 mo of diabetes. Compared with normal mice, diabetic Gpx1+/+ and -/- mice had a two- to threefold increase in urine albumin excretion at 2 and 4 mo of diabetes. At 4 mo, diabetic Gpx1+/+ and -/- mice had equivalent levels of oxidative renal injury (increased kidney reactive oxygen species, kidney lipid peroxidation, urine isoprostanes, kidney deposition of advanced glycoxidation, and nitrosylation end products) and a similar degree of glomerular damage (hypertrophy, hypercellularity, sclerosis), tubular injury (apoptosis and vimentin expression), and renal fibrosis (myofibroblasts, collagen, TGF-beta excretion). A lack of Gpx1 was not compensated for by increased levels of catalase or other Gpx isoforms in diabetic kidneys. Contrary to expectations, this study showed that the high level of Gpx1 expressed in the kidney is not protective against the development of renal oxidative stress and nephropathy in a model of type 1 diabetes.