Effects of naltrexone on lipopolysaccharide-induced sepsis in rats

Naltrexone, an opioid antagonist, has been reported to possess an anti-inflammatory effect via blockade of opioid receptor. The aim of this study is to evaluate the protective effect of naltrexone on LPS-induced septic shock in rats. Sepsis was induced by administration of LPS (10 mg/kg, i.v.) in anesthetized rats. Results demonstrated that pretreatment with naltrexone (10 mg/kg, i.v.) significantly ameliorated hypotension and bradycardia of rats 6 h after LPS administration. In isolated blood vessel, study showed that pretreatment with naltrexone significantly improved norepinephrine-induced vasoconstriction and ACh-induced vasorelaxation in aorta of endotoxemic animals. Naltrexone significantly reduced the elevation of serum glutamate-oxalacetate transaminase and glutamate-pyruvate transaminase (as index of hepatic function) induced by LPS. The infiltration of polymorphonuclear neutrophils into liver 48 h after LPS treatment in mice was also reduced by naltrexone. On the other hand, naltrexone significantly decreased the levels of plasma TNF- and inhibited overproduction of superoxide anions in aortic rings. However, naltrexone did not suppress the overproduction of NO (measured by its metabolites nitrite/nitrate in plasma) and iNOS expression in lungs induced by LPS. In in vitro study, naltrexone did not attenuate non-enzymatic iron-induced lipid peroxidation in rat brain homogenates. In conclusion, pretreatment with naltrexone significantly improved circulatory failure and hepatic dysfunction in sepsis. These effects were associated with reduction of TNF- levels and superoxide anion formation, which may be attributed to antagonism of opioid receptors.     

Inhibition of eNOS Partially Blunts the Beneficial Effects of Nebivolol on Angiotensin II-Induced Signaling in H9c2 Cardiomyoblasts

We have recently illustrated that nebivolol can inhibit angiotensin II (Ang II)-mediated signaling in cardiomyoblasts; however, to date, the detailed mechanism for the beneficial effects of nebivolol has not been studied. Here, we investigated whether the inhibition of NO bioavailability by blocking eNOS (endothelial nitric oxide synthase) using L-NG-nitroarginine methyl ester (L-NAME) would attenuate nebivolol-mediated favorable effects on Ang II-evoked signaling in H9c2 cardiomyoblasts. Our data reveal that the nebivolol-mediated antagonistic effects on Ang II-induced oxidative stress were retreated by concurrent pretreatment with L-NAME and nebivolol. Similarly, the expressions of pro-inflammatory markers TNF-α and iNOS stimulated by Ang II were not decreased with the combination of nebivolol plus L-NAME. In contrast, the nebivolol-induced reduction in the Ang II-triggered mTORC1 pathway and the mRNA levels of hypertrophic markers ANP, BNP, and β-MHC were not reversed with the addition of L-NAME to nebivolol. In compliance with these data, the inhibition of eNOS by L-N⁵-(1-Iminoethyl) ornithine (LNIO) and its upstream regulator AMP-activated kinase (AMPK) with compound C in the presence of nebivolol showed effects similar to those of the L-NAME plus nebivolol combination on Ang II-mediated signaling. Pretreatment with either compound C plus nebivolol or LNIO plus nebivolol showed similar effects to those of the L-NAME plus nebivolol combination on Ang II-mediated signaling. In conclusion, our data indicate that the rise in NO bioavailability caused by nebivolol via the stimulation of AMPK/eNOS signaling is key for its anti-inflammatory and antioxidant properties but not for its antihypertrophic response upon Ang II stimulation.     

Oxysterols increase in diabetic rats

To address whether diabetes enhances lipid peroxidation and attenuates nitric oxide (NO) generation resulting in tissue complications, we measured oxysterols and NO metabolites (NOx) in the tissues of diabetic Wistar rats. After 4 weeks of streptozotocin injection (STZ, 80?mg/kg, i.p.), we measured 7α- and 7β-hydroperoxycholest-5-en-3β-ol (7α-OOH and 7β-OOH), 7α- and 7β-hydroxycholesterol (7α-OH and 7β-OH) and 7-ketocholesterol (7-keto) by HPLC in the kidneys, heart, and liver. All the oxysterols were much higher in the diabetic than in sham rats, while the extent of the increase was higher in the order of the kidney, heart, and liver. Together with high blood urea nitrogen, the data indicate that the kidney is the predominant target of early diabetic complications. Plasma NOx were decreased by 20% in the STZ rats. The enhanced oxidative stress in diabetes would increase oxysterols by peroxidation, while superoxide is known to reduce NO by reaction to form another potent oxidant peroxynitrite.     

Obesity,Aerobic Exercise,and Vascular Disease: The Role of Oxidant Stress

Oxidant formation in the vasculature contributes to vascular disease and dysfunction associated with obesity. In contrast, exercise‐dependent production of oxidants may stimulate adaptive responses that protect against the development of such diseases. In this review, we discuss current concepts in the biology of reactive oxygen and nitrogen species and how their function is modulated in the context of vascular disease, obesity, and aerobic exercise.     

Metabolic Activity of Macrophages Infected with Hantavirus,an Agent of Hemorrhagic Fever with Renal Syndrome

Monocytes/macrophages are thought to play an important role in pathogenesis of viral infections. These cells are involved in distribution and persistence of viruses in the organism and also influence the regulation of immune reactions. The functional and enzymatic activities of macrophages infected with an agent of hemorrhagic fever with renal syndrome were analyzed for the first time. This disease is caused by a virus of the Hantavirus genus, the Bunyaviridae family. Activities of ectoenzymes 5 -nucleotidase and ATPase of the plasma membrane of the hantavirus-infected macrophages decreased along with the antigen accumulation in the infected cells. The contact of phagocytes with hantavirus resulted in activation in the cells of the oxygen-dependent metabolism and NO-synthase. The NO-synthase-dependent system of the infected macrophages was activated earlier than their oxygen-dependent system. The intracellular contents of acid and alkaline phosphatases increased within the first hours after the infection. The bactericidal activity of the hantavirus-infected macrophages relatively to Staphylococcus aureus increased during the specific antigen accumulation in the phagocytes. Thus, the infection of macrophages with hantavirus was associated with intracellular metabolic changes.     

NADPH氧化酶抑制剂apocynin对力竭运动大鼠运动性蛋白尿的影响

目的：研究NADPH氧化酶抑制剂apocynin对力竭运动大鼠运动性蛋白尿产生的影响及其机制。方法：32只SD雄性大鼠随机分为安静对照组（C组）、对照+药物组（CA组）、力竭运动组（E组）、力竭运动+药物组（EA组）。药物注射按10 mg/kg体重,每天一次,连续3 d,并在末次药物注射1 h后进行一次性跑台力竭运动。测定运动后尿UP、血液BUN水平、肾脏ROS浓度、NOS活性、NOS与3-NT蛋白含量。结果：结果显示,E组UP、肾脏ROS、iNOS含量及活性、3-NT明显升高,而EA组的这些指标与C组相比无显著性差异。结论：力竭运动可明显增加肾组织NADPH氧化酶活性,从而产生大量的ROS,后者可迅速地与由肾脏iNOS催化生成的NO反应,产生过量的ONOO^-,诱发运动性蛋白尿的生成。     

Effect of chronic morphine treatment on time-course of free radical processes

The state of an enzymatic component of the antioxidant system, intensity of lipid peroxidation (LPO) in the liver, and the level of blood plasma nitric oxide were investigated in rats subjected to chronic morphine intoxication. Initially male Wistar rats were treated with introperitoneal injections of 1% morphine hydrochloride twice a day. The daily dose of morphine was gradually increased from 10 mg/kg (1–2 days) to 20 mg/kg (3–4 days), and up to 40 mg/kg starting at the fifth day. Animals were subdivided into three groups receiving morphine injections for 7, 14 and 21 days. Control animals were treated with the same volume of 0.9% NaCl injected intraperitoneally. Chronic morphine treatment was accompanied by the marked inhibition of the peroxide-utilizing antioxidants in liver. This created favorable conditions for H₂O₂ toxicity and triggered LPO chain reactions. However, low level of thiobarbituric acid reactive products suggests involvement of some scavenger(s) of H₂O₂, which inhibits hydrogen-peroxide induced free radical processes. In vitro experiments suggest that morphine may be involved into reduction of H₂O₂ level, whereas administration of morphine to rats may also employ nitric oxide as the scavenger of reactive oxygen species.     

Proteasome activation and nNOS down-regulation in neuroblastoma cells expressing a Cu,Zn superoxide dismutase mutant involved in familial ALS

Reactive oxygen and nitrogen species have emerged as predominant effectors of neurodegeneration. We demonstrated that expression of the fully active G93A Cu,Zn superoxide dismutase mutant in neuroblastoma cells is associated with an increased level of oxidatively modified proteins, in terms of carbonylated residues. A parallel increase in proteasome activity was detected and this was mandatory in order to assure cell viability. In fact, proteasome inhibition by lactacystin or MG132 resulted in programmed cell death. Nitrosative stress was not involved in the oxidative unbalance, as a decrease in neuronal nitric oxide production and down-regulation of neuronal nitric oxide synthase (nNOS) level were detected. The nNOS down-regulation was correlated to increased proteolytic degradation by proteasome, because comparable levels of nNOS were detected in G93A and parental cells upon treatment with lactacystin. The altered rate of proteolysis observed in G93A cells was specific for nNOS as Cu,Zn superoxide dismutase (Cu,Zn SOD) degradation by proteasome was influenced neither by its mutation nor by increased proteasome activity. Treatment with the antioxidant 5,5'-dimethyl-1-pyrroline N-oxide resulted in inhibition of protein oxidation and decrease in proteasome activity to the basal levels. Overall these results confirm the pro-oxidant activity of G93A Cu,Zn SOD mutant and, at the same time, suggest a cross-talk between reactive oxygen and nitrogen species via the proteasome pathway.     

Influence of antioxidants on NO-dependent induction of heme oxygenase-1 in U937 monocytes

Thiol antioxidants are known to inhibit the nitric oxide-dependent induction of the hemoxygenase-1 gene (HOX-1). To estimate the degree to which the inhibitory effect of thiol antioxidants is accounted for by them scavenging oxidized NO derivatives or their precursors, the reactive oxygen and nitrogen species (ROS and RNS), we studied the inhibitory effect of nonthiol antioxidants: dimethyl sulfoxide, dimethylthiourea, sodium salicylate, sodium formate, uric acid, catalase, and superoxide dismutase. Partial inhibition of NO-dependent HOX-1 induction was observed in the presence of the nonpolar HO scavengers dimethyl sulfoxide and dimethylthiourea. The antioxidants which selectively bind other ROS had no effect on HOX-1 expression. To reveal the role of RNS in NO-dependent HOX-1 induction, cells were treated with the NO-generating compound DPTA-NO in the presence of 2-phenyl-4,4,5,5,-tetramethylimidazole-1-oxyl 3 oxide (PTIO), which oxidizes NO to NO₂. PTIO proved to significantly enhance NO-dependent HOX-1 induction. Thiol antioxidants completely inhibited the stimulating effect of PTIO, which is evidence that their inhibitory effect is explained by RNS scavenging. The results of this study indicate that antioxidants can be used to modulate the cell response to NO.Translated from Molekulyarnaya Biologiya, Vol. 39, No. 1, 2005, pp. 89–95.Original Russian Text Copyright © 2005 by Litvinov, Prasolov, Bouton, Drapier, Turpaev.     

硝普钠缓解镧引起的黑麦草幼苗生长抑制和根系氧化损伤

采用水培方法,研究了外源一氧化氮（NO）供体硝普钠（SNP）对300 μmol·L^-1 LaCl₃胁迫下黑麦草幼苗生长和根系活性氧代谢的影响。结果表明：在LaCl₃胁迫下,喷施50 μmol·L^-1 SNP能够抑制镧（La）从黑麦草根系向地上部的转运,缓解La对幼苗生长的抑制作用;提高幼苗根系超氧化物歧化酶和抗坏血酸过氧化物酶活性,降低过氧化物酶活性及谷胱甘肽、脯氨酸、H₂O₂、丙二醛含量、超氧阴离子产生速率和质膜相对透性,对过氧化氢酶活性和抗坏血酸含量无显著影响。表明NO可通过活性氧代谢的调节,缓解高浓度La胁迫对黑麦草幼苗生长的抑制作用。     

Nitric oxide, induced by wounding, mediates redox regulation in pelargonium leaves

The subject of this study was the participation of nitric oxide (NO) in plant responses to wounding, promoted by nicking of pelargonium ( Pelargonium peltatum L.) leaves. Bio-imaging with the fluorochrome 4,5-diaminofluorescein diacetate (DAF-2DA) and electrochemical in situ measurement of NO showed early (within minutes) and transient (2 h) NO generation after wounding restricted to the site of injury. In order to clarify the functional role of NO in relation to modulation of the redox balance during wounding, a pharmacological approach was used. A positive correlation was found between NO generation and regulation of the redox state. NO caused a slight restriction of post-wounded O₂⁻ production, in contrast to the periodic and marked increase in H₂O₂ level. The observed changes were accompanied by time-dependent inhibition of catalase (CAT) and ascorbate peroxidase (APX) activity. The effect was specific to NO, since the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5 tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) reversed the inhibition of CAT and APX, as well as temporarily enhancing H₂O₂ synthesis. Finally, cooperation of NO/H₂O₂ restricted the depletion of the low-molecular weight antioxidant pool ( i.e . ascorbic acid and thiols) was positively correlated with sealing and reconstruction changes in injured pelargonium leaves ( i.e . lignin formation and callose deposition). The above results clearly suggest that NO may promote restoration of wounded tissue through stabilisation of the cell redox state and stimulation of the wound scarring processes.     

一氧化氮对小麦叶片老化过程的调节

用不同浓度(0.05、0.10、0.20、0.50 mmol/L)的外源一氧化氮(nitric oxide,NO)供体硝普钠(sodiumnitroprusside,SNP)处理正常生长小麦(Triticum aestivum L.)叶片(二叶一心期时全展第一叶).结果显示低浓度SNP(0.05、0.10、0.20 mmol/L)可以明显降低叶片H2O2和MDA的水平,其中0.10 mmol/LSNP的作用最为明显;而较高浓度SNP(0.50 mmol/L)则作用相反.进一步采用0.10 mmol/L SNP处理不同叶位的小麦叶片(四叶一心期),结果表明低浓度NO对不同老化阶段中叶片的H2O2、O-2和MDA累积都有缓解作用,并明显减缓叶绿素、可溶性叶蛋白尤其是Rubisco的降解,有效延缓了叶片的老化进程.在完整叶绿体体外老化实验中也发现,不同浓度SNP(0.05、0.10、0.20、0.50、1.00、5.00 mmol/L)的作用同样表现双重性,其中0.20 mmol/L SNP对膜结构及Rubisco保护作用最明显.上述结果证实,低浓度外源NO可延缓小麦叶片的老化过程,并可能与其降低叶片活性氧(ROS)水平及缓解氧化损伤有关.     

一氧化氮对小麦叶片老化过程的调节

用不同浓度(0．05、0．10、0．20、0．50mmol／L)的外源一氧化氮(nitric oxide,NO)供体硝普钠(sodium nitroprusside,SNP)处理正常生长小麦(Triticum aestivum L．)叶片(二叶一心期时全展第一叶)。结果显示低浓度SNP(0．05、0．10、0．20mmol／L)可以明显降低叶片H2O2和MDA的水平,其中0．10mmol／L SNP的作用最为明显;而较高浓度SNP(0．50mmol／L)则作用相反。进一步采用0．10mmol／L SNP处理不同叶位的小麦叶片(四叶一心期),结果表明低浓度NO对不同老化阶段中叶片的H2O2、O2^7和MDA累积都有缓解作用,并明显减缓叶绿素、可溶性叶蛋白尤其是Rubisco的降解,有效延缓了叶片的老化进程。在完整叶绿体体外老化实验中也发现,不同浓度SNP(0．05、0．10、0．20、0．50、1．00、5．00mmol／L)的作用同样表现双重性,其中0．20mmol／L SNP对膜结构及Rubisco保护作用最明显。上述结果证实,低浓度外源NO可延缓小麦叶片的老化过程,并可能与其降低叶片活性氧(ROS)水平及缓解氧化损伤有关。     

植物细胞一氧化氮信号转导研究进展

一氧化氮（nitric oxide,NO）作为重要的信号分子,调控植物的种子萌发、根形态建成和花器官发生等许多生长发育过程,并参与气孔运动的调节以及植物对多种非生物胁迫和病原体侵染的应答过程。已经知道,精氨酸依赖的NOS途径和亚硝酸盐依赖的NR途径是植物细胞NO产生的主要酶促合成途径。NO及其衍生物能够直接修饰底物蛋白的金属基团、半胱氨酸和酪氨酸残基,通过金属亚硝基化、巯基亚硝基化和Tyr．硝基化等化学修饰方式,调节靶蛋白的活性,并影响cGMP和Ca2＋信使系统等下游信号途径,调控相应的生理过程。最新的一些研究结果也显示,MAPK级联系统与NO信号转导途径之间存在复杂的交叉调控。此外,作为活跃的小分子信号,NO和活性氧相互依赖并相互影响,共同介导了植物的胁迫应答和激素响应过程。文章综述了植物NO信号转导研究领域中一些新的研究进展,对NO与活性氧信号途径间的交叉作用等也作了简要介绍。     

Effect of inhaled crystalline silica in a rat model: Time course of pulmonary reactions

Numerous investigations have been conducted to elucidate mechanisms involved in the initiation and progression of silicosis. However, most of these studies involved bolus exposure of rats to silica, i.e. intratracheal instillation or a short duration inhalation exposure to a high dose of silica. Therefore, the question of pulmonary overload has been an issue in these studies. The objective of the current investigation was to monitor the time course of pulmonary reactions of rats exposed by inhalation to a non-overload level of crystalline silica. To accomplish this, rats were exposed to 15 mg/m³ silica, 6 h/day, 5 days/week for up to 116 days of exposure. At various times (5–116 days exposure), animals were sacrificed and silica lung burden, lung damage, inflammation, NF-B activation, reactive oxygen species and nitric oxide production, cytokine production, alveolar type II epithelial cell activity, and fibrosis were monitored. Activation of NF-B/DNA binding in BAL cells was evident after 5 days of silica inhalation and increased linearly with continued exposure. Parameters of pulmonary damage, inflammation and alveolar type II epithelial cell activity rapidly increased to a significantly elevated but stable new level through the first 41 days of exposure and increased at a steep rate thereafter. Pulmonary fibrosis was measurable only after this explosive rise in lung damage and inflammation, as was the steep increase in TNF- and IL-1 production from BAL cells and the dramatic rise in lavageable alveolar macrophages. Indicators of oxidant stress and pulmonary production of nitric oxide exhibited a time course which was similar to that for lung damage and inflammation with the steep rise correlating with initiation of pulmonary fibrosis. Staining for iNOS and nitrotyrosine was localized in granulomatous regions of the lung and bronchial associated lymphoid tissue. Therefore, these data demonstrate that the generation of oxidants and nitric oxide, in particular, is temporally and anatomically associated with the development of lung damage, inflammation, granulomas and fibrosis. This suggests an important role for nitric oxide in the initiation of silicosis.     

Role of Vanilloid Receptors in the Capsaicin-Mediated Induction of iNOS in PC12 Cells

The vanilloid receptor 1(VR1) is a nonselective cation channel that is activated by pungent vanilloid compound, extracellular protons, or noxious heat. mRNA of VR1 and vanilloid receptor 1-like receptor (VRL1) were expressed in PC12 cells, and only VRI mRNA was detected in glioma and A10 cell lines. VRI protein was demonstrated in PC12 cells by immunocytochemistry and Western blotting. Capsaicin (CPS), the VRI receptor agonist, led to an increase in intracellular calcium ion, and this effect was blocked by pretreatment with VR1 receptor antagonist capsazepin (CPZ). Treatment of PC12 cells with low concentration of CPS (5-50 microM) increased reactive oxygen species (ROS) production, and inducible nitric oxide synthase (iNOS) was expressed after CPS treatment for 24 h. These CPS-induced changes are inhibited by pretreatment of CPZ. These findings suggest that CPS-induced iNOS expression through the VR1 and/or VRL1-mediated pathway, and this may explain the CPS-mediated physiological and pathological effects in neuron system.