Brain Blood Flow Modulates the Neurotoxic Action of Hyperbaric Oxygen via Neuronal and Endothelial Nitric Oxide

Studies on conscious rats with inhibition of NO synthase were used to assess the dynamics of brain blood flow and EEG traces during hyperbaric oxygenation at 4 or 5 atm. Oxygen at a pressure of 4 atm induced cerebral vasoconstriction in intact animals and decreased blood flow by 11–18% (p < 0.05) during 60-min exposure to hyperbaric oxygenation. Paroxysmal EEG activity and oxygen convulsions did not occur in rats at 4 atm of O₂. At 5 atm, convulsive activity appeared on the EEG at 41 ± 1.9 min, and blood flow decreased significantly during the first 20 min; blood flow increased by 23 ± 9%, as compared with controls, (p < 0.01) before the appearance of convulsions on the EEG. Prior inhibition of NO synthase I (NOS I) and NO synthase III (NOS III) with N-nitro-L-arginine methyl ester (L-NAME, 30 mg/kg) or inhibition only of NOS I with 7-nitroindazole (7-NI, 50 mg/kg) prevented the development of hyperoxic hyperemia and paroxysmal spikes on the EEG during hyperbaric oxygenation at 5 atm. These results show that hyperbaric oxygen induces changes in cerebral blood flow which modulate its neurotoxic action via nitric oxide synthesized both in neurons and in cerebral vessels.     

The Roles of Nitric Oxide and Carbon Dioxide Gas in the Neurotoxic Actions of Oxygen under Pressure

The hypothesis that in conditions of hyperbaric oxygenation, nitric oxide (NO) modulates the vasodilatory effect of CO₂ in the brain and thus accelerates the neurotoxic action of oxygen was verified experimentally. Conscious rats breathed atmospheric air or oxygen at 5 atm and blood flow in the striatum was measured before and after inhibition of carbonic anhydrase with acetazolamide, which causes retention of CO₂ in the brain. Acetazolamide (35 mg/kg) increased blood flow in the animals when breathing air by 38 ± 7.4% (p < 0.01), while preliminary inhibition of NO synthase with N^ω-nitro-L-arginine-methyl ester (L-NAME, 30 mg/kg) significantly weakened its vasodilatory action. Inhibition of carbonic anhydrase in animals breathing hyperbaric oxygen at 5 atm prevented cerebral vasoconstriction, increased brain blood flow, and accelerated the development of oxygen convulsions. The vasodilatory effect of acetazolamide in hyperbaric oxygenation was significantly reduced in animals pretreated with the NO synthase inhibitor, such that the latent period of convulsions increased. The results obtained here provide evidence that in conditions of extreme hyperoxia, NO modulates the cerebral hyperemia developing in conditions of CO₂ retention in the brain and accelerates the development of the neurotoxic actions of hyperbaric oxygen.__________Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 90, No. 4, pp. 428–436, April, 2004.     

惊恐障碍一氧化氮、一氧化氮合酶及脑血流研究

目的:研究惊恐障碍(PD)一氧化氮、一氧化氮合酶及脑血流的改变以及影响这些改变的相关因素.方法:研究组为30例PD组,对照组为30例广泛焦虑障碍(GAD) PD组,30例GAD组及22例正常对照(NC)组.所有样本均测一氧化氮(NO)、一氧化氮合酶(NOS)及脑血流量.比较PD组分别与GAD PD组、GAD组及正常对照(NC)组之间的差别,并在PD组内部对有关指标作多元逐步回归分析.结果:PD组NO浓度较GAD组低(67.22±39.62,102.8±60.69).NOS测重浓度PD组与其他各组无显著性差异(P>0.05).脑血流测定,PD组左侧大脑中动脉收缩峰、右侧大脑中动脉收缩峰及右侧大脑中动脉平均峰较NC组低且差异有显著性.右侧椎动脉收缩峰较GAD组及NC组低.PD组NO浓度与HAMA负相关.左侧大脑中动脉收缩峰与左侧大脑中动脉平均峰、右侧大脑中动脉收缩峰及精神性焦虑呈正相关,与右侧大脑中动脉平均峰及右侧大脑前动脉收缩峰、年龄及女性呈负相关.右侧大脑中动脉收缩峰与右侧大脑中动脉平均峰、右侧大脑前动脉收缩峰呈正相关,与右侧大脑前动脉平均峰呈负相关.右侧大脑中动脉平均峰与右侧大脑中动脉收缩峰、左侧大脑中动脉平均峰、右侧大脑前动脉平均峰及NO呈正相关,与年龄、左侧大脑中动脉收缩峰及右侧大脑前动脉收缩峰呈负相关.右侧椎动脉收缩峰与右侧椎动脉平均峰、左侧大脑中动脉平均峰呈正相关,与左侧大脑前动脉收缩峰、右侧大脑前动脉平均峰呈负相关.结论:NO、脑血流量改变可能是PD的神经生物学机制之一.测定NO水平及脑血流量可作为PD的诊断或鉴别诊断指标.     

旋磁场对大鼠脏器SOD活力和NO含量的影响

目的:探讨旋磁场对大鼠肝组织、肾组织、心组织和脑组织中超氧化物歧化酶(SOD)活力和一氧化氮(NO)含量的影响.方法:用邻苯三酚法测定SOD活力;NO含量的测定采用改良的Griess法.结果:在30mT磁场中曝磁30min,大鼠肝、肾、心和脑组织中SOD活力显著高于对照组(P＜0.01或P＜0.05);大鼠肝组织和肾组织中NO含量显著高于对照组(P＜0.01);心组织NO含量高于对照组(P＜0.05);脑组织NO含量无明显变化.结论:旋磁场对大鼠脏器组织SOD活力和NO含量有一定影响.     

The Expression of Neuronal Nitric Oxide Synthase in the Brain of the Mouse During Embryogenesis

The distribution of neuronal nitric oxide synthase (nNOS) in the process of normal mouse brain growth from embryonic (E) Day 11 to postnatal (P) Day 1 was investigated by means of immunohistochemical and immunofluorescent methods. Our results demonstrated that nNOS positive neurons appeared early in superficial cortex at E11. At E13, nNOS positive neurons were located in lateral hypothalamus and amygdala, and temporarily in medullar and ventral hypothalamic neuroepithelia. From E15 to P0, nNOS positive neurons were distributed in superior and inferior colliculi, positive staining could also be seen in superior and inferior tectal neuroepithelium at E15. From E17 to birth, the medial geniculate nucleus had a high density of nNOS labeling. The distribution of nNOS gradually increased and extended laterally in embryo brain, which in turn implies that NO might be involved in the development of mouse brain. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

一氧化氮与活化的小鼠腹腔巨噬细胞细胞毒作用关系的研究

本文选用Raji和K562两种细胞株作靶细胞,以LPS和IFN-γ作为巨噬细胞(MΦ)的激活剂,研究了一氧化氮(NO)在活化的小鼠腹腔巨噬细胞(PEMΦ)细胞毒中的作用以及靶细胞对MΦ合成NO的影响.结果表明,PEMΦ被激活后,合成NO量大为增加,并对Raji和K562两种靶细胞表现出很高的细胞毒效应;加入NO合酶抑制剂L-NMMA,PEMΦ对Raji的杀伤作用受到显著抑制,而对K562的细胞毒作用则不受影响.此外,在实验条件下,Raji细胞的存在可促进PEMΦ产生NO,而K562细胞则有削弱PEMΦ合成NO的倾向.     

Protective action of superoxide dismutase in experimental myocarditis

Bulletin of Experimental Biology and Medicine -     

芪参复康胶囊对大鼠睡眠剥夺后脑组织NO含量和SOD活性的影响

目的观察芪参复康胶囊对大鼠睡眠剥夺（SD）后脑组织一氧化氮（NO）含量和超氧化物歧化酶（SOD）活性的影响及行为变化,探讨芪参复康胶囊对睡眠剥夺的保护作用。方法采用小平台水环境法制作大鼠TSD模型,观察大鼠经过3天SD后额叶和海马NO含量和SOD活性,并观察采用芪参复康胶囊干预对这些指标的影响。结果与正常对照组比较,SD大鼠额叶和海马NO含量和SOD活性均升高。芪参复康胶囊干预后大鼠脑内NO含量及SOD活性明显下降（P〈0.01~0.05）。结论芪参复康胶囊具有改善生化代谢作用,可减轻睡眠剥夺对机体的损害。     

强迫游泳对小鼠脑内一氧化氮及一氧化氮合酶的影响研究

目的 :探讨应激对小鼠脑内一氧化氮 (NO)及一氧化氮合酶 (NOS)的影响及意义。方法 :将 6 0只雄性昆明品系小鼠随机分为 3组。其中对照组 2 0只 ,强迫游泳分 2组各 2 0只。分别于强迫游泳 (实验组 )后 1h (一组 )、 2h (二组 )取脑组织检测NO含量及NOS活性。结果 :对照组NO及NOS分别为 2 7 4 7± 15 16 μmol/gprot、 2 16± 0 5 3U/mgprot。实验一组为 17 83± 5 6 3μmpl/gprot、 2 76± 0 87U/mgprot ;实验二组为 11 38± 1 2 2 μmpl/gprot、 3 2 9± 0 4 1U/mgprot。急性应激后 1hNO水平降低并有统计学意义 (t =2 6 7,P <0 0 5 ) ;2h后进一步降低 (t=5 0 5 ,P <0 0 1)。急性应激后 1hNOS活性增高并有统计学意义 (t =-2 4 2 ,P<0 0 5 )。应激后NO与NOS变化呈显著性负相关 (r=-0 316 ,P <0 0 5 )。结论 :神经递质NO及NOS参与了中枢神经急性应激反应 ,且NO水平降低、NOS活性增高。     

低剂量γ射线辐照对血清一氧化氮及一氧化氮合酶水平的影响

目的：观察低剂量γ射线照射人离体外周血对血清中一氧化氮（NO）和一氧化氮合酶（NOS）水平的影响。方法：采集10份健康献血员全血，肝素抗凝，然后采用γ射线照射，照射剂量率为17Gy／min，总吸收剂量为1Gy，分别于照射前及照射后1h，2h采用分光光度法检测血清中NO含量和NOS活性。结果：经γ射线照射1h后，血清中NO及NOS水平与照射前比较明显升高（P〈0.01）；照射后2h，血清中NOS水平与照射后1h比较无统计学差异（P〉0、05），但是还明显高于照射前的水平（P〈0．01）；在照射后2h，血清中NO含量与照射后1h比较明显降低（P〈0.01），但仍明显高于照射前水平（P〈0．01）。结论：采用剂量为1Gy的γ射线照射外周血，可引起血清中NO水平及NOS活性的显著升高．从而为低剂量辐照自体血回输对肿瘤的辅助治疗提供了理论支持。     

病毒性肝炎中一氧化氮合酶调节的分子生物学机制

研究发现一氧化氮(NO)参与肝细胞的多项生理功能的调节,参与各种肝病的病理过程。一氧化氮具有潜在的抗病毒活性,一氧化氮合酶(NOs)作为产生一氧化氮的限速酶,不但参与一氧化氮的生成,还与一氧化氮的各种生理功能密切相关。了解与阐明肝细胞中一氧化氮合酶的分子生物学作用调节机制,有利于揭示病毒性肝炎的发病机理     

被动吸烟对大鼠脑组织iNOS表达的影响

目的　研究被动吸烟大鼠脑组织诱发型一氧化氮合酶 (iNOS)的变化 ,探讨iNOS在吸烟导致脑损伤中的作用机制。方法　制备被动吸烟大鼠模型 ,采用免疫组织化学ABC方法检测脑组织iNOS表达 ,应用光镜、透射电镜观察海马神经元的病理改变。结果　正常对照组大鼠大脑皮层、海马、纹状体均有少量iN OS表达 ,短期吸烟组与正常对照组比较有显著差异 (P <0 0 1) ,长期小量或大量吸烟组 (3个月 )各脑区iN OS表达显著高于正常对照组和短期吸烟组 (P<0 0 1)。长期大量吸烟组可见海马神经元变性改变。结论　吸烟可使脑组织iNOS活化表达增强生成过多的NO造成脑神经细胞毒性损伤 ,存在量效、时效关系。     

Elevated Nitric Oxide Concentration in the Seminal Plasma of Infertile Males: Nitric Oxide Inhibits Sperm Motility

PROBLEM: To evaluate the “effect of nitric oxide in the seminal plasma on sperm motility. METHOD: Seminal plasma concentrations of NO₂^—, a stable end product of nitric oxide, of 108 males of infertile couples and 15 proven fertile donors were measured and compared with spermatogram parameters. Motile sperm was incubated with a nitric oxide-generating drug, sodium nitroprusside, for 6 hr in the absence or presence of oxyhemoglobin, an inhibitor of nitric oxide. RESULTS: The NO₂^— concentration in the seminal plasma was 6.58±0.56 μM in 26 infertile males with leukocytospermia, 5.51±0.25 μM in 82 infertile males without leukocytospermia, and 3.91±0.16 μM in 15 controls. There was a significant correlation between the NO₂^— concentration and sperm motility. Sodium nitroprusside reduced the sperm motility in a dose- and time-dependent manner and its reduction was completely inhibited by the addition of oxyhemoglobin. CONCLUSION: These findings indicate that nitric oxide concentration in the seminal plasma of infertile males is elevated and that nitric oxide is an inhibitor of sperm motion.     

原发性高血压患者血清NO、NOS及其亚型水平的分析

目的:测定原发性高血压患者外周血中血清一氧化氮(NO)、一氧化氮合酶(NOS)及其亚型水平,探讨NO/NOS系统参与血压调节的可能机制.方法:原发性高血压患者135例,正常对照组35例.采用化学法检测所有病例外周血的一氧化氮(NO)、总NOS、诱导型一氧化氮合酶(iNOS)和结构型一氧化氮合酶(cNOS)水平并作统计学分析.结果:高血压组NO、NOS、iNOS和cNOS水平均低于正常对照组,且差异具有显著性意义(分别为:P＜0.05,P＜0.01,P＜0.01,P＜0.01);iNOS/cNOS比值与正常对照组相比无显著差异(P＞0.05);对照组和高血压组的NOS浓度与iNOS和cNOS浓度均呈显著正相关;高血压组的cNOS水平与iNOS水平呈显著负相关.结论:高血压患者NO、NOS及其亚型浓度值可以作为临床评估高血压的参考指标;iNOS在正常人体内有表达;在高血压情况下,机体有通过增加iNOS的表达来弥补cNOS水平的病理性降低、调控NOS总体水平从而调节和平衡血压的趋势.     

Nitric oxide and the role of blood pressure variability to the kidney

Blood pressure variability is buffered by at least two mechanisms: the arterial baroreceptor reflex and nitric oxide (NO). Only recently is the importance of blood pressure variations on cardiovascular control being investigated. Here we report of a study performed in conscious dogs, in which renovascular hypertension was induced. Reduction of renal arterial pressure (RAP) to 85 mmHg for 24 h elicited profound hypertension by 60 mmHg (vs. control: 110 ± 3 mmHg; P < 0.01). This was accompanied by reduced volume and sodium excretion (–48% of control, P < 0.01 and –80% of control, P < 0.01, respectively) and augmented renin release by more than two‐fold (P < 0.01). This intervention was compared with a protocol in which RAP was reduced to the same mean value, however, RAP oscillated by ±10 mmHg at 0.1 Hz. This manoeuvre led to a transient increase in NO₃ excretion in urine (P < 0.01), blunted antidiuresis (–14% of control) as well as antinatriuresis (–40% of control) and attenuated the increased renin release by 30% (P < 0.05). In consequence, the magnitude of blood pressure increase was only half as high as that observed during static reduction of RAP (P < 0.01). It is concluded that blood pressure oscillations to the kidney have a profound influence on water and electrolyte balance and on renin release, which alleviates the onset of Goldblatt hypertension.     

睡眠剥夺对大鼠一氧化氮和一氧化氮合酶的影响

目的：探讨睡眠剥夺对大鼠脑组织一氧化氮（NO）及一氧化氮合酶（NOS）影响。方法：采用小平台水环境法（Flower Pot)制作大鼠睡眠剥夺模型，采用化学法和酶法观察不同时间睡眠剥夺后大鼠额叶、海马、中脑和下丘脑NO含量及NOS活性变化。结果：与正常对照组及大平台组比较，大鼠在SD后额叶和海马的NO含量及NOS活性增高，有显著性差异（P＜0．01－0．05），其余脑区无显著性差异（P＞0．05）。随着剥夺时间的延长，额叶和海马NO含量及NOS活性增高更加明显。结论：睡眠剥夺可致NO及NOS升高，可能与其学习障碍有关，NO可能参与大鼠的睡眠调节。     

犬小肠缺血再灌注后氧自由基改变及脾脏免疫细胞凋亡基因的表达

目的研究犬小肠缺血再灌注后血中一氧化氮(NO)浓度、超氧化物岐化酶(SOD)活性的改变和脾脏中凋亡相关基因表达和意义。方法通过阻断肠系膜上动脉,建立缺血再灌注模型,检测血中NO和SOD活性的改变。用免疫组织化学SP法观察C FOS、BAXP53和BCL2在脾脏组织中的表达。结果再灌注30min后,NO浓度无明显下降(46.1±4.0),至第4天达最低水平(25.9±5.0),而至第7天又明显回升(42.5±5.0)。从血管阻断30min至第7天,SOD活性持续升高(98.4±8.0),但各时点之间差别不明显。再灌注30、60min,1、4和7d后,C FOS、BAX和P53的表达明显增加,C FOS阳性细胞率分别为:35%、45%、50%、56%和80%,BAX阳性细胞率分别为:50%、61%、60%、65%和75%,P53的阳性细胞率分别为:30%、42%、45%、48%和50%,BCL2阳性细胞率仅为5%至10%。C FOS和BAX阳性细胞率明显高于BCL2。结论小肠缺血再灌注后可造成血中氧自由基、脾脏免疫细胞的凋亡基因表达改变及远隔器官的次级损伤。     

Neuronal Nitric Oxide Synthase Activation Is Involved in Insulin-Mediated Cardiovascular Effects in the Nucleus Tractus Solitarii of Rats

Neuronal nitric oxide synthases (nNOS) is distributed throughout the central nervous system (CNS) and has been proposed to modulate neuronal activity in the nucleus tractus solitarii (NTS). Here, we investigated whether the activation of nNOS is involved in insulin-induced cardiovascular responses in the NTS. Insulin (100 IU/ml) was unilaterally microinjected into the NTS, and the cardiovascular effects were evaluated before and after microinjection of the nNOS inhibitors 7-nitroindazole (7-NI) (5 pmol) and N(5)-(1-imino-3-butenyl)-l-ornithine (vinyl-L-NIO) (600 pmol). Western blot and immunohistochemical analyses were performed to determine nNOS phosphorylation levels after insulin or phosphoinositide 3-kinase (PI3K) inhibitor LY294002 microinjection into the NTS. Unilateral microinjection of insulin into the NTS produced prominent depressor and bradycardic effects in WKY rats. Pretreatment with the nNOS inhibitors 7-NI and Vinyl-L-NIO attenuated the cardiovascular response evoked by insulin in Wistar-Kyoto (WKY) rats. Moreover, Western blot analysis showed a significant increase in nNOS (16.5±0.4-fold; P<0.05; n=4) phosphorylation after insulin injection, whereas the PI3K inhibitor LY294002 abolished the insulin-induced effects. In situ nNOS phosphorylation was found to be increased in the NTS after insulin injection. Furthermore, co-immunoprecipitation assay showed Akt and nNOS can bind to each other as detected by phospho-Akt^S473 and phospho-nNOS^S1416 antibodies. In vitro kinase assay showed insulin activated Akt can directly phosphorylate nNOS^S1416. These results demonstrated that nNOS may couple with the activation of the insulin receptor, via the liberation of NO, in order to participate in central cardiovascular regulation of WKY rats.     

Nitric oxide regulates ovarian blood flow in the rat during the periovulatory period

BACKGROUND: The aim of this study was to characterize the roles of nitric oxide (NO) on the rat ovarian blood flow (OBF) during the preovulatory period. METHODS AND RESULTS: Immature Sprague-Dawley rats were primed with pregnant mares' serum gonadotrophin (PMSG, 15 IU) and given hCG (15 IU) 48 h later. The ovary was exposed 48-56 h after PMSG, a laser Doppler probe was attached to the ovarian surface and OBF was measured at two time periods: preovulatory (PO) 48 h after PMSG and ovulatory (OV) 6-8 h after hCG. A non-selective NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), was injected i.v. (4 and 10 mg/kg) or intrabursally (1 mg/kg). Intravenous administration of L-NAME to OV rats rapidly increased blood pressure and reduced OBF by 30%, which returned to the pretreatment level within 30 min. L-NAME given into the ovarian bursa of both PO and OV rats did not affect blood pressure and reduced OBF by nearly 40%, which remained low throughout the experiment. Intravenous injection of hCG to PO rats increased OBF to 116.1% at 5 min and 133.5% at 30 min in relation to the pretreatment level. When L-NAME was given intrabursally, subsequent hCG injection was without effect. CONCLUSIONS: These results indicate that locally produced NO is important for the maintenance and increase of rat OBF during the preovulatory period.