The role of nitric oxide in the cardiac effects of hydrogen peroxide

Oxidative stress mediated by hydrogen peroxide (H₂O₂) increases coronary flow (CF) in Langendorff-perfused rat hearts. We investigated the possible role of nitric oxide (NO) in H₂O₂-induced vasolidation. A dose-response study was conducted to find a concentration of H₂O₂ which increased CF without influencing left ventricular developed (LVDP) or end-diastolic (LVEDP) pressures. 80 (n = 10),100 (n = 7), 120 (n = 7),140 (n = 7),160 (n = 7), and 180 (n = 10) M H₂O₂ was infused for 10 min, followed by recovery for 50 min. 80 M H₂O₂ increased CF to a maximum of 143 ± 4 (mean ± S.E.M) percent of initial value after 15 min observation (p < 0.001 compared to buffer only), with no effect on LVDP or LVEDP. Another series of hearts were perfused with N-nitro-L-Arginine methylester (L-NAME, 1 M), methylene blue (MB, 50 M), or haemoglobin (Hb, 10 M), without (n = 7 in each) or with (n = 10 in each) 80 M H₂O₂ for 10 min. L-NAME, MB, and Hb alone increased CF, but attenuated the H₂O₂-induced increase of CF. LVDP was depressed when L-NAME, MB, or Hb were given in conjunction with 80 M H₂O₂. In summary, H₂O₂ concentration-dependently increased LVEDP and depressed LVDP. The H₂O₂-induced increase of CF was independent of concentration. Inhibition of NO synthesis, action, or soluble guanylate cyclase attenuated the H₂O₂-induced increase of CF, and depressed LVDP when given together with H₂O₂. H₂O₂ induces a NO-dependent vasodilation, and inhibition of NO is detrimental to left ventricular function after H₂O₂-mediated oxidative stress.     

Reactive oxygen species and nitric oxide regulate mitochondria-dependent apoptosis and autophagy in evodiamine-treated human cervix carcinoma HeLa cells

The redox environment of the cell is currently thought to be extremely important to control either apoptosis or autophagy. This study reported that reactive oxygen species (ROS) and nitric oxide (NO) generations were induced by evodiamine time-dependently; while they acted in synergy to trigger mitochondria-dependent apoptosis by induction of mitochondrial membrane permeabilization (MMP) through increasing the Bax/Bcl-2 or Bcl-x_L ratio. Autophagy was also stimulated by evodiamine, as demonstrated by the positive autophagosome-specific dye monodansylcadaverine (MDC) staining as well as the expressions of autophagy-related proteins, Beclin 1 and LC3. Pre-treatment with 3-MA, the specific inhibitor for autophagy, dose-dependently decreased cell viability, indicating a survival function of autophagy. Importantly, autophagy was found to be promoted or inhibited by ROS/NO in response to the severity of oxidative stress. These findings could help shed light on the complex regulation of intracellular redox status on the balance of autophagy and apoptosis in anti-cancer therapies.     

Role of endoplasmic reticulum stress and autophagy in the transition from acute kidney injury to chronic kidney disease

Acute kidney injury (AKI) and chronic kidney disease (CKD) are global health concerns with increasing rates in morbidity and mortality. Transition from AKI-to-CKD is common and requires awareness in the management of AKI survivors. AKI-to-CKD transition is a main risk factor for the development of cardiovascular disease and progression to end-stage kidney disease. The mechanisms driving AKI-to-CKD transition are being explored to identify potential molecular and cellular targets for renoprotective drug interventions. Endoplasmic reticulum (ER) stress and autophagy are involved in the process of AKI-to-CKD transition. Excessive ER stress results in the persistent activation of unfolded protein response, which is an underneath cause of kidney cell death. Moreover, ER stress modulates autophagy and vice-versa. Autophagy is a degradation defensive mechanism protecting cells from malfunction. However, the underlying pathological mechanism involved in this interplay in the context of AKI-to-CKD transition is still unclear. In this review, we discuss the crosstalk between ER stress and autophagy in AKI, AKI-to-CKD transition, and CKD progression. In addition, we explore possible therapeutic targets that can regulate ER stress and autophagy to prevent AKI-to-CKD transition to improve the long-term prognosis of AKI survivors.     

Cerebroprotective effects of hydrogen sulfide in homocysteine-induced neurovascular permeability: Involvement of oxidative stress,arginase, and matrix metalloproteinase-9

An elevated level of homocysteine (Hcy) leads to hyperhomocysteinemia (HHcy), which results in vascular dysfunction and pathological conditions identical to stroke symptoms. Hcy increases oxidative stress and leads to increase in blood–brain barrier permeability and leakage. Hydrogen sulfide (H₂S) production during the metabolism of Hcy has a cerebroprotective effect, although its effectiveness in Hcy-induced neurodegeneration and neurovascular permeability is less explored. Therefore, the current study was designed to perceive the neuroprotective effect of exogenous H ₂S against HHcy, a cause of neurodegeneration. To test this hypothesis, we used four groups of mice: control, Hcy, control + sodium hydrosulfide hydrate (NaHS), and Hcy + NaHS, and an HHcy mice model in Swiss albino mice by giving a dose of 1.8 g of dl -Hcy/L in drinking for 8–10 weeks. Mice that have 30 µmol/L Hcy were taken for the study, and a H ₂S supplementation of 20 μmol/L was given for 8 weeks to all groups of mice. HHcy results in the rise of the levels of superoxide and nitrite, although a concomitant decrease in the level of superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and arginase in oxidative stress and a concomitant decrease in the endogenous level of H ₂S. Although H ₂S supplementation ameliorated, the effect of HHcy and the levels of H ₂S returned to the average level in HHcy animals supplemented with H ₂S. Interestingly, H ₂S supplementation ameliorated neurovascular remodeling and neurodegeneration. Thus, our study suggested that H ₂S could be a beneficial therapeutic candidate for the treatment of Hcy-associated neurodegeneration, such as stroke and neurovascular disorders.     

一氧化氮供体对过氧化氢引起的心肌细胞损伤的保护作用

关于一氧化氮(NO)对心肌细胞是否具有保护作用目前尚存在争议,为探讨NO对过氧化氢(H2O2)引起的心肌细胞损伤是否具有保护作用及其可能的机制,实验将体外培养的新生大鼠心肌细胞分为3组(1)阴性对照组(Normal组);(2)H2O2组H2O2(0.1mmol/L)与心肌细胞共育4h;(3)S-亚硝基-N-乙酰青霉胺(SNAP)+H2O2组NO供体SNAP(0.5mmol/L)处理心肌细胞10min后,加入H2O2与心肌细胞共育4 h.用流式细胞术检测心肌细胞凋亡率,心肌细胞损伤程度以心肌细胞存活率和乳酸脱氢酶(lactate dehydrogenase,LDH)活性来表示,同时检测心肌细胞超氧化物歧化酶(superoxide dismutase,SOD)活性和丙二醛(MDA)含量.通过激光共聚焦显微术检测在不同处理条件下心肌细胞胞内钙的变化.结果表明,正常心肌细胞LDH活性和细胞存活率分别为631.4±75.6 U/L和93.1±6.2%,细胞凋亡率为0;H2O2处理细胞后可使细胞LDH活性显著增高(1580.5±186.7 U/L,P＜0.01),细胞存活率明显下降(58.3±7.6%,P＜0.01),流式细胞仪检测到大量心肌细胞凋亡,凋亡率为26.4±5.7%;SOD活性较正常细胞19.67±0.85 NU/ml显著下降,为14.73±1.68 NU/m(P＜0.01),MDA含量较正常细胞6.95±0.83μmol/L显著增高,为15.35±3.49μmol/L(P＜0.01).SNAP预处理细胞可显著提高心肌细胞存活率(79.7±9.3%,P＜0.01),降低LDH活性和细胞凋亡率(分别为957.8±110.9 U/L和9.1±3.3%,P＜0.01);并提高细胞抗氧化能力,表现为较H2O2处理组的SOD活性增高(21.36±3.11 NU/ml,P＜0.01),MDA含量下降(9.12±1.47 μmol/L,P＜0.01).激光共聚焦显微镜检测结果表明,H2O2可升高细胞内钙,而SNAP则可降低细胞内钙,SNAP预处理细胞后可取消H2O2升高细胞内钙的作用.上述结果提示,NO供体SNAP可对抗H2O2对心肌细胞的损伤,其机制与提高心肌细胞抗氧化损伤能力和对抗H2O2引起的细胞内钙超载有关.     

Detection of advanced oxidation protein products in patients with chronic kidney disease by a novel monoclonal antibody

Abstract

Advanced oxidation protein products (AOPP) as a biomarker of oxidative stress has been demonstrated in chronic kidney disease (CKD) patients; however, current methods to detect the accumulation of AOPP in serum and in tissues are limited and unreliable. This study generated a monoclonal antibody (mAb) designated 3F2, that reacts specifically with hypochlorous acid (HOCl)-modified proteins, but not with the native forms or with other types of oxidative modifications. Notably, mAb 3F2 recognizes the AOPP deposited in renal tissues of AOPP-treated rats and of patients with different kinds of CKD. Moreover, this mAb can almost completely inhibit the production of reactive oxygen species in RAW264.7 cells induced by AOPP (p < 0.001). In conclusion, mAb 3F2 can be used to detect AOPP specifically in serum and in tissues, and this antibody can potentially provide an important tool and new insight into research on diseases related to oxidative stress.     

Effects of exercise and lifestyle intervention on oxidative stress in chronic kidney disease

Objectives: Determine the effects of a 12-month exercise and lifestyle intervention program on changes in plasma biomarkers of oxidative stress in pre-dialysis chronic kidney disease (CKD) patients.

Methods: A total of 136 stage 3–4 CKD patients were randomized to receive standard nephrological care with (N?=?72) or without (N?=?64) a lifestyle and exercise intervention for 12 months. Plasma total F₂-isoprostanes (IsoP), glutathione peroxidase (GPX) activity, total antioxidant capacity (TAC), anthropometric and biochemical data were collected at baseline and at 12 months.

Results: There were no significant differences between groups at baseline. There were no significant differences in changes for standard care and lifestyle intervention, respectively, in IsoP (p?=?0.88), GPX (p?=?0.87), or TAC (p?=?0.56). Patients identified as having high IsoP at baseline (>250 pg/mL) had a greater decrease in IsoP with lifestyle intervention compared to standard care; however, the difference was not statistically significant (p?=?0.06). There was no difference in the change in kidney function (eGFR) between standard care and lifestyle intervention (p?=?0.33).

Discussion: Exercise and lifestyle modification in stage 3–4 CKD did not produce changes in systemic biomarkers of oxidative stress over a 12-month period, but patients with high IsoP may benefit most from the addition of intervention to standard care.     

氢气对慢性间歇性低氧大鼠肝脏氧化应激损伤的改善作用

目的：研究氢气对慢性间歇性低氧大鼠肝脏损伤的改善作用。方法：24只雄性成年SD大鼠,随机分为3组（n=8）：常氧组（Norm）、慢性间歇性低氧组（CIH）、氢气+慢性间歇性低氧组（H₂+CIH）。Norm组暴露于空气中,CIH组与H₂+CIH组接受间歇性低氧处理5周,其中H₂+CIH组在间歇性低氧处理前给予1 h 67%浓度的氢气吸入。5周后比较各组大鼠血清氧化应激指标、炎症因子指标、肝酶水平、血脂水平,并在电镜下观察大鼠肝组织超微结构变化。结果：与Norm组相比,CIH组肝组织超微结构受损严重,谷丙转氨酶（ALT）、谷草转氨酶（AST）水平显著升高（P<0.05）;血清8-羟基脱氧鸟苷（8-OHdG）水平显著升高;超氧化物歧化酶（SOD）活性显著降低;白介素-6（IL-6）水平显著升高。与CIH组相比,H₂+CIH组肝组织超微结构损伤减轻,ALT、AST水平显著降低（P<0.05）;8-OHdG与IL-6水平显著降低,SOD活性显著升高。与Norm组相比,CIH组IL-1水平升高;血清TC、TG、LDL水平升高,但无统计学差异。HDL在各组之间无统计学差异。结论：氢气可以减轻慢性间歇性低氧对大鼠肝脏的损伤,有效降低氧化应激水平,保护肝细胞受损。     

The involvement of nitric oxide in maneb- and paraquat-induced oxidative stress in rat polymorphonuclear leukocytes

Oxidative stress plays a crucial role in the manifestations of maneb (MB) and paraquat (PQ)-induced toxicity including MB+PQ-induced Parkinson's disease (PD). Polymorphonuclear leukocytes (PMNs) actively participate in the oxidative stress-mediated inflammation and organ toxicity. The present study was undertaken to investigate the MB- and/or PQ-induced alterations in the indices of oxidative stress in rat PMNs. Animals were treated with or without MB and/or PQ in an exposure time dependent manner. In some sets of experiments, the animals were pre-treated with NOS inhibitors N^G-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AG) along with respective controls. A significant increase in myeloperoxidase (MPO), superoxide dismutase (SOD), nitric oxide, iNOS expression and lipid peroxidation (LPO) was observed in PMNs of MB- and/or PQ-treated animals, while catalase and glutathione S-transferase (GST) activities were attenuated. L-NAME and AG significantly reduced the augmented nitrite content, iNOS expression and MPO activity to control level in MB and PQ exposed animals. Although the augmented LPO was also reduced significantly in L-NAME and AG treated rat PMNs, the level was still higher as compared with controls. Alterations induced in SOD and GST activities were not affected by NOS inhibitors. The results thus suggest that MB and/or PQ induce iNOS-mediated nitric oxide production, which in turn increases MPO activity and lipid peroxidation, thereby oxidative stress.     

Role of nitric oxide dependence on nitric oxide synthase-like activity in the water stress signaling of maize seedling

Nitric oxide (NO) has been known as an important signal in plant antioxidative defense but its production and roles in water stress are less known. The present study investigated whether NO dependence on a NO synthase-lika (NOS) activity is involved in the signaling of drought-induced protective responses in maize seedlings. NOS activity, rate of NO release and drought responses were analyzed when NO donor sodium nitroprusside (SNP), NO scavenger c-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramathylimidazoline-1-oxyl-3-oxide) and NOS inhibitor L-NAME (NG-nitro-L-arginine methyl ester) were applied to both detached maize leaves and whole plants. Both NOS activity and the rate of NO release increased substantially under dehydration stress. The high NOS activity induced by c-PTIO as NO scavenger and NO accumulation Inhibited by NOS inhibitor L-NAME In dehydration-treated maize seedlings Indicated that most NO production under water deficit stress may be generated from NOS-like activity. After dehydration stress for 3 h, detached maize leaves pretreated with NO donor SNP maintained more water content than that of control leaves pretreated with water. This result was consistent with the decrease in the transpiration rate of SNP-treated leaves subjected to drought treatment for 3 h. Membrane permeability, a cell injury index, was lower in SNP-trested maize leaves under dehydration stress for 4 h when compared with the control leaves. Also, superoxide dismutsse (SOD) activity of SNP combined drought treatment maize leaves was higher than that of drought treatment alone, indicating that exogenous NO treatment alleviated the water loss and oxidative damage of maize leaves under water deficit stress. When c-PTIO as a specific NO scavenger was applied, the effects of applied SNP were overridden. Treatment with L-NAME on leaves also led to higher membrane permeability, higher transpiration rate and lower SOD activities than those of control leaves, indicating that NOS-like activity was involved in the antioxidative defense under water stress. These results suggested that NO dependence on NOS-like activity serves as a signaling component in the induction of protective responses and is associated with drought tolerance in maize seedlings.     

The contradictory effects of nitric oxide in caerulein-induced acute pancreatitis in rats

This study was planned to observe the effects of nitric oxide synthesis on the antioxidative defense enzymes and pancreatic tissue histology in caerulein-induced acute pancreatitis. Acute pancreatitis was induced by intraperitoneal injections of 50 µg/kg caerulein, L-arginine used for NO induction and N^ω-nitro-L-arginine methyl ester (L-NAME) used for NO inhibition. In the caerulein group acinar cell degeneration, interstitial inflammation, oedema and haemorrhage were detected. Pancreatic damage scores were decreased with both NO induction and inhibition (p<0.05). MDA, GSH-Px, CAT, GSH and SOD activities were significantly changed in the caerulein group and indicated increased oxidative stress. Both NO induction and inhibition decreased this oxidative stress. It is concluded that both nitric oxide induction and inhibition ameliorated caerulein-induced acute pancreatitis. The findings indicate that a certain amount of NO production has beneficial effects in experimental acute pancreatitis, but uncontrolled over-production of NO may be detrimental.     

Exercise training restores oxidative stress and nitric oxide synthases in the rostral ventrolateral medulla of renovascular hypertensive rats

Abstract

We hypothesize that exercise training (EX) reverses the level of nitric oxide (NO) and oxidative stress into rostral ventrolateral medulla (RVLM) of renovascular hypertensive rats (two kidneys, one clip - 2K1C). Microinjections of L-arginine (5 nmol), L-NAME (10 nmol), or saline (100 nl) were made into RVLM of 2K1C and normotensive (SHAM) rats sedentary (SED) or subjected to swimming for 4 weeks. mRNA expression (by qRT-PCR) of nitric oxide synthases isoforms (nNOS, eNOS, and iNOS), manganese superoxide dismutase (MnSOD), copper and zinc superoxide (Cu/ZnSOD), catalase (CAT), NADPH oxidase subunit p22^phox, concentration of thiobarbituric acid-reactive substances (TBARS), and CAT activity into RVLM were evaluated. The mean arterial pressure was reduced in 2K1C EX compared with that in 2K1C SED rats. L-arginine into RVLM induced hypertensive effect in 2K1C and SHAM SED rats, while L-NAME prevented hypertensive effect only in SHAM-SED. EX reduced hypertensive effect of L-arginine in SHAM and 2K1C rats. mRNA expression of NOS isoforms, p22^phox, and concentration of TBARS were increased while CAT and Cu/ZnSOD expression and CAT activity decreased into RVLM of 2K1C-SED compared with SHAM-SED rats. Additionally, EX reversed mRNA expression of CAT and NOS isoforms, concentration of TBARS, and CAT activity into RVLM of 2K1C-EX rats. These data suggest that the levels of NOS and oxidative stress into RVLM are important to determine the level of hypertension. Furthermore, EX can restore the blood pressure by reversing the levels of NOS and CAT expression, and reducing TBARS concentration into RVLM for the physiological state.     

Induction of mitochondrial oxidative stress in astrocytes by nitric oxide precedes disruption of energy metabolism

Inhibition of the mitochondrial electron transport chain (ETC) ultimately limits ATP production and depletes cellular ATP. However, the individual complexes of the ETC in brain mitochondria need to be inhibited by approximately 50% before causing significant depression of ATP synthesis. Moreover, the ETC is the key site for the production of intracellular reactive oxygen species (ROS) and inhibition of one or more of the complexes of the ETC may increase the rate of mitochondrial ROS generation. We asked whether partial inhibition of the ETC, to a degree insufficient to perturb oxidative phosphorylation, might nonetheless induce ROS production. Chronic increase in mitochondrial ROS might then cause oxidative damage to the ETC sufficient to produce prolonged changes in ETC function and so compound the defect. We show that the exposure of astrocytes in culture to low concentrations of nitric oxide (NO) induces an increased rate of O2*- generation that outlasts the presence of NO. No effect was seen on oxygen consumption, lactate or ATP content over the 4-6 h that the cells were exposed to NO. These data suggest that partial ETC inhibition by NO may initially cause oxidative stress rather than ATP depletion, and this may subsequently induce irreversible changes in ETC function providing the basis for a cycle of damage.     

Activation of Nrf2/Keap1 signaling and autophagy induction against oxidative stress in heart in iron deficiency

We investigated the effects of dietary iron deficiency on the redox system in the heart. Dietary iron deficiency increased heart weight and accumulation of carbonylated proteins. However, expression levels of heme oxygenase-1 and LC3-II, an antioxidant enzyme and an autophagic marker, respectively, in iron-deficient mice were upregulated compared to the control group, resulting in a surrogate phenomenon against oxidative stress.     

Neuroprotective effects of hydrogen sulfide on Parkinson’s disease rat models

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra (SN). The present study was designed to examine the therapeutic effect of hydrogen sulfide (H₂S, a novel biological gas) on PD. The endogenous H₂S level was markedly reduced in the SN in a 6‐hydroxydopamine (6‐OHDA)‐induced PD rat model. Systemic administration of NaHS (an H₂S donor) dramatically reversed the progression of movement dysfunction, loss of tyrosine‐hydroxylase positive neurons in the SN and the elevated malondialdehyde level in injured striatum in the 6‐OHDA‐induced PD model. H₂S specifically inhibited 6‐OHDA evoked NADPH oxidase activation and oxygen consumption. Similarly, administration of NaHS also prevented the development of PD induced by rotenone. NaHS treatment inhibited microglial activation in the SN and accumulation of pro‐inflammatory factors (e.g. TNF‐α and nitric oxide) in the striatum via NF‐κB pathway. Moreover, significantly less neurotoxicity was found in neurons treated with the conditioned medium from microglia incubated with both NaHS and rotenone compared to that with rotenone only, suggesting that the therapeutic effect of NaHS was, at least partially, secondary to its suppression of microglial activation. In summary, we demonstrate for the first time that H₂S may serve as a neuroprotectant to treat and prevent neurotoxin‐induced neurodegeneration via multiple mechanisms including anti‐oxidative stress, anti‐inflammation and metabolic inhibition and therefore has potential therapeutic value for treatment of PD.