一氧化氮与脑血管痉挛性神经元损伤和L-精氨酸的作用

目的:探讨一氧化氮(NO)与蛛网膜下腔出血(SAH)后脑血管痉挛(CVS)所致神经元损伤的关系及L-精氨酸(L-Arg)的保护作用。方法: 应用血管内穿刺法建立大鼠SAH模型,将动物随机分为假手术组(SO组)、SAH组和SAH+L-Arg组。动态检测24 h内大脑顶叶皮层局部脑血流量(rCBF),测量基底动脉(BA)管径变化,测定不同时点血清NO(NO^-₂/NO^-₃)水平和血浆ET-1含量,并行海马神经元形态学观察。 结果: 假手术对各项指标无显著影响。SAH组术后rCBF迅速降低,1 h达最低值,并持续24 h;SAH后BA管径明显缩小;血清NO^-₂／NO^-₃含量明显减少,血浆ET-1含量逐渐增加,海马神经元显著损伤。与SAH组比较,SAH+L-Arg组rCBF下降的速度减慢、程度减轻;BA管径缩小的程度减轻;血清NO^-₂／NO^-₃水平降低和血浆ET-1含量增高的变化减轻;海马神经元损伤的程度减轻。结论: 血清NO浓度的降低参与了CVS性神经元损伤,L-Arg对之具有一定减轻作用。     

Role of nitric oxide in prevention of ethanol-induced gastric damage by CuNSN a copper-chelating compound

CuNSN a bis (2-benzimidazolyl)thiother complex with copper, has been shown to prevent the formation of acute gastric mucosal lesions induced by acetylsalicylic acid and ethanol. In the present study we have investigated the role of NO in CuNSN protection from ethanol-induced gastric damage. For this purpose we have used the inhibitor of NO biosynthesis, N^G-nitro-L-arginine (L-NNA) as well as L- or D-arginine. Gastric mucosal damage caused by ethanol was dose-dependently increased by i.v. administration of graded dose of L-NNA. The effect of L-NNA was completely antagonized by the administration of L-arginine while D-arginine did not cause a reduction in the damage. Treatment with CuNSN has shown a significant protection against the damage produced by ethanol. This protection was not reversed by L-NNA and was significant as compared to the corresponding control group. The combination of L-NNA plus L-arginine potentiates this protection. These results suggest that NO synthesis is not involved in the protection afforded by CuNSN.     

一氧化氮与利血平致大鼠胃粘膜损伤的关系

目的: 探讨一氧化氮(NO)与利血平致大鼠胃粘膜损伤机制的关系。方法: 从大鼠腹腔内注入利血平复制成胃粘膜损伤模型,并随机分为实验组和对照组。用镉还原加格氏显色法和改良硫代巴比妥酸法分别测定两组大鼠血浆及胃粘膜中NO和丙二醛(MDA)含量,用还原型辅酶Ⅱ组织化学方法结合图像分析对两组大鼠胃壁内一氧化氮合酶(NOS)进行定位、定量研究。结果: 实验组大鼠血浆、胃粘膜中NO含量显著低于对照组(P＜0.01),而其MDA含量则显著高于对照组(P＜0.05,P＜0.01);实验组大鼠胃壁内NOS阳性神经细胞、阳性神经纤维密度及其着色深度均显著低于对照组(P＜0.05,P＜0.01)。结论: 利血平致大鼠胃粘膜损伤的发生可能与大鼠胃壁内NOS阳性神经成分减少,体内NO不足使其对胃粘膜的保护作用减弱有一定关系。     

一氧化氮与氧自由基在大鼠急性乙醇性胃粘膜损伤中的作用

目的：研究大鼠乙醇性急性胃粘膜损伤中，一氧化氮（NO）与氧自由基的作用及二者之间的关系，以探讨NO对急性胃粘膜损伤发挥保护作用的机制。方法：以酒精给大鼠灌胃制备急性胃粘膜损伤模型，应用NO合酶抑制剂（L-NAME）及NO前体L-精氨酸（L-Arg）按不同分组尾静脉注射。取门脉血测定NO和丙二醛（MDA）水平，并取出胃进行形态学观察。结果：酒精灌胃后，大鼠门脉血NO含量降低，MDA水平升高，胃粘膜损伤面积随酒精浓度升高而增加；尾静脉给予L-NAME后，NO含量进一步下降，而MDA量更为升高，粘膜损伤进一步加重；L-Arg与L-NAME合用后，NO和MDA含量均有所恢复，粘膜损伤也明显减轻。门脉血NO与MDA含量呈负相关关系。结论：氧自由基的大量生成是乙醇性急性胃粘膜损伤的重要发生机制之一。内源性NO能够清除氧自由基，改善胃粘膜微循环，减轻急性胃粘膜损伤程度，对胃粘膜有保护作用。     

一氧化氮与基质金属蛋白酶介导的血管重构在动脉瘤中的作用

Nitric oxide (NO) and matrix metaUoproteinases (MMPs) are important in vascular remold-ing, especially in abdominal aortic aneurysm. NO may be associated with aneurysms by modulating MMPs expression and activity.     

Role of early vascular damage in the pathogenesis of gastric haemorrhagic mucosal lesions induced by indomethacin in rats

Early vascular injury is a key element in the pathogenesis of gastric haemorrhagic mucosal lesions which develop rapidly after intragastric (i.g.) administration of ethanol, HCl or NaOH. The sequence of vascular events leading to gastric lesions has not, however, been investigated in detail with ulcerogenic non-steroidal anti-inflammatory drugs such as indomethacin (IND). Accordingly, experiments were performed in rats using the vascular tracer Monastral blue to assess whether vascular lesions precede and are subsequently associated with mucosal lesions induced by oral (p.o.) or subcutaneous (s.c.) administration of IND. Fasted female Sprague–Dawley rats (150–180 g) were given IND either at 100 mg/kg, p.o. or 200 mg/kg s.c. and killed 15, 30, 120 or 240 minutes later. Monastral blue, 3% saline 1 ml/kg, was injected intravenously under ether anaesthesia 3 minutes before autopsy and the formalin fixed, glycerol cleared stomachs were examined microscopically for deposition of the dye particles on damaged blood vessels. The percentage area of Monastral blue labelled vessels (measured by stereomicroscopic planimetry) at 15 minutes after oral IND was 10.1 ± 1.5% (mean ± s.e.m.) of glandular stomach and increased progressively to 64.5 ± 3.0% at 240 minutes. Gastric haemorrhagic lesions (also measured by stereomicroscopic planimetry) were first evident at 30 minutes (0.2 ± 0.03%; mean ± s.e.m.), and developed progressively to 2.0±0.3% total area of glandular mucosa at 240 minutes. Subcutaneous injection of IND resulted in a delayed time of onset for the appearance and the extent of mucosal lesions (first appearing at 120 minutes, 0.1 ± 0.03% area) compared with that from oral administration of the drug, but as with oral IND the vascular damage (first appearance at 15 minutes, 7.5 ± 3.6%) clearly preceded the occurrence of gastric lesions. The observations of microvascular dye labelling were paralleled by observations of the electronmicroscopic appearance of endothelial cell disruption in the region adjacent to superficial mucous cells and accumulation of red blood cells in the interstitium at 20–60 minutes. We conclude that vascular injury precedes haemorrhagic mucosal damage in the pathogenesis of IND-induced acute gastric mucosal lesions.     

Central nitric oxide inhibition modifies metabolic adjustments induced by exercise in rats

The influence of the central nervous system on metabolic function is of interest in situations deviating from basal states, such as during exercise. Our previous study in rats demonstrated that central nitric oxide (NO) blockade increases metabolic rate, reducing mechanical efficiency during exercise. To assess the role of brain nitric oxide in the plasma glucose, lactate and free fatty acids (FFAs) concentrations of rats submitted to an incremental exercise protocol on a treadmill until fatigue, 1.43 micromol (2 microl) of N(omega)-nitro-l-arginine methyl ester (L-NAME, n=6), a NO synthase inhibitor, or 2 microl of 0.15M NaCl (SAL, n=6) was injected into the lateral cerebral ventricle (icv) of male Wistar rats immediately before exercise (starting at 10 m/min, with increments of 1m/min every 3 min until fatigue, 10% inclination). Blood samples were collected through a chronic jugular catheter at rest and during exercise until fatigue. During exercise, the L-NAME-treated animals had the following metabolic response compared to controls: (1) an increased hyperglycemic response during the first 60% of time to fatigue; (2) higher plasma lactate levels; and (3) a significant transitory increase in plasma free fatty acids during the dynamic phase of exercise that returned to basal levels earlier than controls during the steady state phase of exercise. In addition L-NAME-treated rats fatigued earlier than controls. The data indicate that the inhibition of the brain nitrergic system induced by icv L-NAME treatment disrupted the accuracy of the neural mechanism that regulates plasma glucose and free fatty acids mobilization during exercise in rats.     

NO在脂多糖诱发的肝硬化大鼠肝性脑病中的作用

目的:探讨一氧化氮(NO)在LPS诱发的肝硬化大鼠肝性脑病中所起的作用。方法:采用复合因素复制肝硬化大鼠模型,于实验8周末开始分别用09%盐水、L-精氨酸(L-arg)和N-亚硝基L-精氨酸(LNNA)给大鼠灌胃2周。在处死大鼠前4h,腹腔内一次性注射LPS3mg/kg,以诱发大鼠肝性脑病。结果:L-arg组大鼠活动灵活且脑电图基本正常,LNNA组出现肝性脑病。L-arg组脑组织NO₂^-/NO₃^-含量明显高于LNNA组(P<0.05),脑组织组胺含量明显低于LNNA组(P<0.05)。脑组织中组胺含量与脑组织中NO₂^-/NO₃^-含量呈负相关。结论:NO能抑制LPS诱发肝硬化大鼠肝性脑病的发生。     

Role of nitric oxide in activation of human T lymphocytes induced by bacterial superantigen

The involvement of nitric oxide (NO) in the regulation of human T cell response to bacterial superantigen (staphylococcal enterotoxin B) was studied. It was shown that stimulated T lymphocytes are the main source of NO. This superantigen markedly increased NO production and triggered the proliferative response of mononuclear cells from healthy individuals; the degree of apoptosis was low. In patients with purulent surgical diseases with high spontaneous and induced NO production, superantigen enhanced apoptosis of lymphocytes and induced anergy of T cells to enterotoxins. Increasing the concentration of NO in cultured cells from healthy individuals in the presence of NO donors also stimulated apoptosis and inhibited proliferative activity. These data suggest that NO regulates T lymphocyte response to superantigens. The increased production of NO probably contributes to the development of immunosuppression during bacterial infection. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 10, pp. 402–406, September, 2000     

Role of nitric oxide in indomethacin-induced gastric mucosal dysfunction in the rat

The present study was undertaken to explore the role of nitric oxide (NO) in the pathogenesis of experimental non-steroidal anti-inflammatory drug (NSAID)-induced gastropathy. We assessed the role of NO inhibition and donation in indomethacin-induced gastric mucosal dysfunction. The stomach was perfused with vehicle (control) for 20 min, followed by indomethacin (10 mg ml-1 in 1 25 % sodium bicarbonate, pH 8 4) for 120 min. NG-nitro-L-arginine methyl ester (L-NAME, 5 and 10 mg kg-1, I.V. bolus), L-arginine, D-arginine (100 mg kg-1 I.V. bolus, 10 mg kg-1 h-1, 2 h infusion) and the NO donor glyceryl trinitrate (GTN) were given at the same time (20, 40 and 80 microg kg-1 min-1, 15 min infusion) as perfusion with indomethacin was started. Epithelial permeability was quantified by measuring blood-to-lumen clearance of 51Cr-labelled EDTA. Indomethacin caused a 20-fold increase in 51Cr-EDTA leakage compared with that of the control group. Treatment with L-NAME or L-arginine did not affect the indomethacin-induced alterations in mucosal permeability. Administration of GTN (20 microg kg-1 min-1) significantly reduced the indomethacin-induced mucosal dysfunction. By contrast, higher doses of GTN (80 microg kg-1 min-1) exacerbated epithelial dysfunction induced by indomethacin. Elevated levels of carbonyls and myeloperoxidase (MPO) observed after indomethacin administration were significantly reduced, to the control values, when GTN (20 microg kg-1 min-1) was administered along with indomethacin. These data suggest that NO from exogenous sources can exert a dual action on the integrity of the gastric mucosa challenged by indomethacin. Low doses of GTN can prevent mucosal dysfunction induced by indomethacin, while higher doses of GTN may exacerbate the increases in epithelial permeability.     

Role of nitric oxide in zymosan induced paw inflammation and thermal hyperalgesia

OBJECTIVE: To assess the involvement of spinal inducible nitric oxide synthase (iNOS) in inflammation and nociception. MATERIALS AND METHODS: The time course of iNOS mRNA expression in rat spinal cord and inflamed paw was assessed by means of quantitative real time RT-PCR. In addition, the effects of the iNOS inhibitor L-NIL on inflammatory paw edema and thermal hyperalgesia were studied in comparison to those of the NO-donor RE-2047. L-NIL (3, 9, 27 and 81 mg/kg) and RE-2047 (3, 9 and 27 mg/kg) or vehicle were administered orally 15 min prior to the intraplantar injection of 0.625 mg zymosan. RESULTS: Following zymosan injection, mRNA expression of iNOS increased in the inflamed paw and spinal cord with a maximum at 2.5 and 4 h, respectively. In the spinal cord iNOS mRNA started to decline at 10 h whereas it remained at maximum in the inflamed paw up to the end of the observation period of 24 h. As expected, RE-2047 had significant pronociceptive and proinflammatory effects. L-NIL significantly reduced paw inflammation at 27 and 81 mg/kg but failed to reduce hyperalgesia at the doses tested. CONCLUSIONS: The results show that iNOS is upregulated in the inflamed tissue and spinal cord with a similar time course. The effects obtained with L-NIL suggest that iNOS differently contributes to the inflammatory and nociceptive response induced by zymosan.     

Actions of nitric oxide on the acute gastrointestinal damage induced by PAF in the rat

The actions of nitric oxide (NO) on the acute gastrointestinal damage induced by platelet-activating factor (PAF) have been investigated in the rat.S-nitroso-N-acetyl penicillamine, which spontaneously generates NO, dose-dependently inhibited PAF-induced gastrointestinal plasma leakage, a measure of the initiation of vascular damage. The inhibitor of NO synthase,N^G-monomethyl-l-arginine substantially potentiated gastrointestinal damage and plasma leakage induced byE. coli endotoxin, but had no effect on that induced by intravenous infusion of PAF.Endogenous NO may thus have a protective role in the gastrointestinal vascular that can be mimicked by generators of NO. The protection afforded by endogenous NO may, however, be dependent on the nature of the inflammatory stimulus used to induce gastrointestinal damage.     

Actions of nitric oxide on the acute gastrointestinal damage induced by PAF in the rat

The actions of nitric oxide (NO) on the acute gastrointestinal damage induced by platelet-activating factor (PAF) have been investigated in the rat.S-nitroso-N-acetyl penicillamine, which spontaneously generates NO, dose-dependently inhibited PAF-induced gastrointestinal plasma leakage, a measure of the initiation of vascular damage. The inhibitor of NO synthase,N ^G-monomethyl-l-arginine substantially potentiated gastrointestinal damage and plasma leakage induced byE. coli endotoxin, but had no effect on that induced by intravenous infusion of PAF.Endogenous NO may thus have a protective role in the gastrointestinal vascular that can be mimicked by generators of NO. The protection afforded by endogenous NO may, however, be dependent on the nature of the inflammatory stimulus used to induce gastrointestinal damage.     

一氧化氮合酶抑制物在胃黏膜损伤中的作用与机制

目的:研究一氧化氮合酶抑制物非对称性二甲基精氨酸(ADMA)在不同因素诱发的胃黏膜损伤中的作用,并初步探讨其机制。方法:用乙醇、吲哚美辛、应激诱发大鼠胃黏膜损伤模型,检测胃黏膜溃疡指数(UI),一氧化氮(NO)和ADMA水平,以及二甲基精氨酸-二甲胺水解酶(DDAH)的活性;检测幽门螺旋杆菌(Hp)处理胃黏膜上皮细胞(GES-1)细胞培养液中NO,ADMA和TNF-α水平,以及细胞中DDAH活性。结果:乙醇、吲哚美辛、应激诱发大鼠胃黏膜损伤的同时ADMA水平显著升高以及DDAH活性下降;Hp处理GES-1细胞24 h后,ADMA和TNF-α水平显著升高,DDAH活性下降;外源性ADMA也能显著升高GES-1细胞TNF-α水平。结论:ADMA是促进胃黏膜损伤的重要因子,除抑制NO生成外,还具有直接致炎作用。     

Protection of insulin secreting cells from nitric oxide induced cellular damage by crosslinked hemoglobin

Pancreatic islets and insulinoma cells are particularly vulnerable to serious damage by cytotoxic nitric oxide (NO) and/or oxidative stress, most probably due to their low expression levels of antioxidant enzymes. This cellular damage has been regarded as one of major obstacles to success of encapsulated islet transplantation for the treatment of type 1 diabetes. As an approach to preventing NO induced damage, crosslinked hemoglobin (Hb-C) with poly(ethylene glycol) was co-encapsulated with rat islets or insulinoma cells (RINm5F) in alginate/poly(L-lysine)/alginate microcapsules. Hb-C effectively protected the cells from NO damage, generated by treating the cell microcapsules with S-nitroso-N-acetylpenicillamine (SNAP, a nitric oxide donor) at concentrations up to 400 microM, preserving higher viability and insulin secretion than a control group (no SNAP and no Hb-C). When the cells were incubated with SNAP without Hb, there was SNAP concentration dependent cellular damage, and a colorimetric TUNEL assay revealed a typical cell apoptosis sign, indicating DNA damages.     

缺氧新生鼠胃壁内一氧化氮合成酶定量和定位研究

为探讨缺氧新生鼠胃壁局部一氧化氮（ＮＯ）的改变,本文直接测定其胃壁一氧化氮合成酶（ＮＯＳ）活性,并采用ＮＡＤＰＨ二氢硫辛酰胺脱氢酶组织化学方法（ＮＤ法）观察胃壁各层ＮＯＳ分布的变化,结果发现：急性缺氧组与正常组相比,差异无显著性（Ｐ＞０．０５）。但在缺氧缺血性脑病（ＨＩＥ）组,胃壁ＮＯＳ活性明显增高（Ｐ＜０．０１）,ＮＤ法定位显示ＮＯＳ阳性纤维及胞体明显增多表现在肌层,而粘膜及粘膜下层变化不明显。说明窒息时胃动力降低及胃粘膜病变与ＮＯ在胃壁内的改变有关。     

Chondrocyte apoptosis induced by nitric oxide.

Chondrocytes stimulated with IL-1 produce high levels of nitric oxide (NO), which inhibits proliferation induced by transforming growth factor-beta or serum. This study analyzes the role of NO and IL-1 in the induction of chondrocyte cell death. NO generated from sodium nitroprusside induced apoptosis in cultured chondrocytes as demonstrated by electron microscopy, 4',6-dianidino-2-phenylindole dihydrochloride staining, FACS analysis, and histochemical detection of DNA fragmentation. Similar results were obtained with two other NO donors, 3-morpholinosynonimide-hydrochloride and s-nitroso-N-acetyl-D-L-penicillamine. In contrast, oxygen radicals generated by hypoxanthine/xanthine oxidase caused necrosis but did not induce chondrocyte apoptosis. To analyze whether endogenously generated NO induces apoptosis, chondrocytes were stimulated with IL-1, but there was no evidence for apoptotic changes. Combinations of NO inducers such as IL-1, lipopolysaccharide, tumor necrosis factor, and interferon-gamma also failed to trigger apoptosis. IL-1-stimulated chondrocytes are known to produce oxygen radicals that react with NO to form products that can induce cell death in other systems. We thus tested IL-1 in combination with the oxygen radical scavengers N-acetyl cysteine, dimethyl sulfoxide, or 5,5'-dimetylpyrroline 1-oxide. Under these conditions IL-1 was able to induce apoptosis, which was inhibited in a dose-dependent manner by the NO synthase inhibitor N-monomethyl L-arginine. Conversely, endogenous oxygen radicals induced by inflammatory mediators caused necrosis under conditions in which the simultaneous production of NO was reduced. These results suggest that NO, but not oxygen radicals, is the primary inducer of apoptosis in human articular chondrocytes.     

一氧化氮对肾性高血压大鼠主动脉收缩功能的影响

目的:探讨二肾一夹（2K1C）肾性高血压大鼠主动脉收缩功能的改变及其与一氧化氮的关系。 方法:实验分为假手术组、2K1C组、卡托普利组、NAME组和精氨酸组等5组，利用术后4周的肾性高血压大鼠的胸主动脉进行离体血管环实验，并测定主动脉环一磷酸鸟苷（cGMP）的含量。 结果:2K1C肾性高血压大鼠离体主动脉环对苯肾上腺素、血管紧张素Ⅱ、ACh、KCl的收缩反应显著高于假手术组，主动脉cGMP含量明显少于假手术组。卡托普利可逆转2K1C大鼠的上述改变。L-精氨酸可使上述异常的主动脉收缩功能部分恢复，并增加主动脉cGMP含量。一氧化氮合酶抑制剂L-NAME使主动脉cGMP含量进一步减少，主动脉对缩血管物质的收缩反应无进一步增强。各组大鼠的胸主动脉用L-NAME抑制一氧化氮生成后，对硝普钠的最大舒张反应无明显差别。 结论:2K1C肾性高血压大鼠主动脉收缩功能的改变可能与NO合成、释放减少和缩血管物质产生增多有关。     

Role of nitric oxide and histamine in the reflux-related gastric mucosal injury in the rat

Inflammation Research -     

Modulation by nitric oxide of gastric acid secretion in toads

Nitric oxide (NO) is a novel chemical messenger that mediates a variety of biological actions. This study was undertaken to investigate the effects of NO on parietal cell function. The rate of [³H]arginine conversion to [³H]citrulline, a parameter of NO synthase activity, and NO formation (as NO^?₂), were inhibited by the NO synthase inhibitor, N ^G-nitro- L -arginine methyl ester ( L -NAME), in a concentration-dependent manner in the non-stimulated toad gastric mucosa. This range of concentrations of L -NAME provoked stimulation of H⁺ secretion in a similar fashion, which was blocked by L -arginine but not by D -arginine. Pre-treatment with carbachol plus ethylene glycol-bis(β-aminoethyl ether)-N,N,N ′,N ′-tetra-acetic acid (EGTA) prevented the effect of L -NAME on H⁺ secretion and drastically reduced NO synthase activity. L -arginine had an inhibitory effect on H⁺ secretion in non-stimulated and carbachol-stimulated gastric mucosa, which was reversed by L -NAME. Carbachol and pentagastrin, but not histamine, significantly increased NO formation in the toad gastric mucosa. The results suggest that changes in NO synthesis in the gastric mucosa may modulate parietal cell function and that a calcium-dependent mechanism may be involved.