异丙酚、咪达唑仑和硫喷妥钠对大鼠缺氧复氧性脑损伤的影响

为对比观察异丙酚、咪达唑仑和硫喷妥钠对大鼠缺氧复氧脑损伤的保护作用,将Wistar大鼠40只随机分为5组,每组8只,A组:对照组;B～E组:缺氧复氧组,其中C、D、E组:分别给予异丙酚、咪达唑仑和硫喷妥钠。采用酶联免疫吸附法检测大鼠脑组织8-异前列腺素F2α(8-iso-PGF2α)水平,硝酸还原法测定其一氧化氮合酶(NOS)活力和NO含量。结果表明,缺氧复氧后,B、C、D、E各组脑组织中8-iso-PGF2α水平明显升高,而NOS活力和NO含量则明显降低,与A组比较差异有显著意义(P<0.05);C组和D组的脑组织8-iso-PGF2α含量较B组明显降低(P<0.05),但仍然高于A组(P<0.05),NOS活力和NO含量较B组明显升高(P<0.05)但仍然低于A组(P<0.05);D、E组的脑组织8-iso-PGF2α含量明显高于C组(P<0.05),NOS活力和NO含量明显低于C组(P<0.05);D组与E组比较,E组的脑组织8-iso-PGF2α含量明显高于D组(P<0.05),NOS活力和NO含量明显低于D组(P<0.05),但与B组相比无意义(P>0.05)。结论:异丙酚和咪达唑仑能明显降低缺氧复氧后脑组织的8-iso-PGF2α水平,提高内源性NO生成,提示对大鼠缺氧复氧脑损伤有明显的保护作用,且异丙酚的脑保护效应强于咪达唑仑,而硫喷妥钠的脑保护作用不明显。     

褪黑素对大鼠局灶性脑缺血的影响

目的:探讨褪黑素对大鼠局灶性脑缺血保护作用.方法:用线栓法建立大鼠大脑中动脉栓塞(MCAO)模型.大鼠随机分为假手术组、缺血组、褪黑素组(4 mg&#8226;kg 1)、尼莫地平组(0.2 mg&#8226;kg 1).缺血前30 min舌下静脉给药.持续性缺血30 min,6,24 h后处死动物,测定脑梗死体积,脑组织丙二醛(MDA)、一氧化氮(NO)含量和NOS活性(分光光度法);透射电镜观察脑组织超微结构改变.结果:MCAO后,脑梗死体积及MDA含量随时间延长而增大,6 h后基本稳定;缺血30 min NO含量及NOS活性升高,缺血6 h降低,24 h再度升高.与模型组比较,褪黑素组能缩小脑梗死体积、降低脑组织中MDA含量、缺血30 min NO含量及NOS活性升高,6,24 h降低,且显著改善脑组织的超微病变,减少神经细胞的凋亡.结论:褪黑素对大鼠局灶性脑缺血有一定的保护作用,机制可能与降低脑组织中NO含量和NOS活性、减轻脑组织生物膜脂质过氧化损伤及减少神经细胞的凋亡有关.     

大鼠创伤性脑损伤早期脑组织NO含量和NOS活性的变化

目的 探讨一氧化氮（NO）和神经元型NO合酶（nNOS）是否参与创伤性脑损伤（TBI）的发病机理。方法 采用落体法大鼠TBI动物模型，观察大鼠TBI早期脑组织NO含量、NOS活性的动态变化和特异性nNOS抑制剂7-硝基吲唑（7-NI）对其的影响。结果大鼠TBI后30min脑组织NO含量和NOS活性显著升高，伤后2h两者回落，但仍高于对照组；伤后6h两者接近对照组；伤后12hNO含量仍接近对照组，而NOS活性再次高于对照组。结论 NO和nNOS在创伤性脑损伤机制中可能起重要作用。     

银杏叶提取物对糖尿病大鼠一氧化氮水平的影响

目的研究银杏叶提取物(EGb)对糖尿病大鼠心肌、睾丸、脑组织一氧化氮水平的影响。方法用链脲佐菌素制备SD大鼠糖尿病模型。测定EGb对糖尿病大鼠心肌、睾丸、脑组织一氧化氮(NO)的含量及一氧化氮合酶(NOS)、诱导型一氧化氮合酶(iNOS)、结构型一氧化氮合酶(cNOS)的活性的影响。结果与正常组相比,糖尿病大鼠心肌、睾丸组织NO含量及NOS、iNOS活性升高,脑组织NO含量及NOS活性升高。与糖尿病组相比,EGb治疗组大鼠心肌、睾丸组织NO含量及NOS、iNOS活性下降。结论EGb能够对抗糖尿病大鼠过量NO对心肌、睾丸组织的损伤。     

银杏叶提取物对糖尿病大鼠一氧化氮水平的影响

目的 研究银杏叶提取物(EGb)对糖尿病大鼠心肌、睾丸、脑组织一氧化氯水平的影响。方法用链脲佐菌素制备SD大鼠糖尿病模型。测定EGb对糖尿病大鼠心肌、睾丸、脑组织一氧化氯(NO)的含量及一氧化氯合酶(NOS)、诱导型一氧化氯合酶(iNOS)、结构型一氧化氯合酶(cNOS)的活性的影响。结果与正常组相比，糖尿病大鼠心肌、睾丸组织NO含量及NOS，iNOS活性升高，脑组织NO含量及NOS活性升高。与糖尿病组相比，EGb治疗组大鼠心肌、睾丸组织NO含量及NOS、iNOS活性下降。结论 EGb能够对抗糖尿病大鼠过量NO对心肌、睾丸组织的损伤。     

MC-002对脑缺血再灌注损伤大鼠脑组织及血清中NO及NOS的影响

目的 研究MC-002对脑缺血再灌注损伤大鼠脑组织及血清中一氧化氮（NO）、一氧化氮合酶（NOS）含量的影响,探讨其对脑缺血再灌注损伤保护作用的机制.方法 采用改良线栓法,建立大鼠大脑中动脉栓塞（MCAO）脑缺血再灌注模型.将雄性SD大鼠随机分为假手术组、模型组、奥扎格雷钠组（18mg/kg）和MC-002高、中、低剂量组（30、18、10.8mg/kg）.缺血再灌注24h后检测脑组织及血清中NO含量、NOS活性.结果 与假手术组相比,模型组脑组织和血清中NO含量和NOS活性明显升高;与模型组相比,MC-002高、中、低剂量组脑组织和血清中NO含量和NOS活性均明显降低（P＜0.01、0.05）.结论 MC-002对大鼠脑缺血再灌注损伤具有明显的保护作用,其机制可能与降低NOS活性,减少NO含量有关.     

脱氢表雄酮硫酸酯对地佐环平所致记忆损伤小鼠的作用及机制

目的观察脱氢表雄酮硫酸酯(DHEAS)对地佐环平所致记忆损伤小鼠的作用及机制。方法地佐环平(0.15 mg·kg~(-1),ip)造成小鼠记忆损伤模型,利用被动逃避实验评价小鼠记忆成绩,并测定给药后24 h小鼠皮质和海马一氧化氮(NO)的含量和一氧化氮合酶(NOS)的活性。结果在被动逃避实验中,地佐环平造成小鼠记忆损伤,脱氢表雄酮硫酸酯(10、20 mg·kg~(-1),sc)预处理能减少跳台错误次数(P<0.01),延长跳台潜伏期(P<0.01)和避暗潜伏期(P<0.01)。地佐环平降低皮质和海马NOS活性,减少NO含量,脱氢表雄酮硫酸酯(10、20 mg·kg~(-4),sc)预处理升高皮质和海马NOS的活性(P<0.01),进一步使皮质和海马(P相似文献   

新生儿缺氧缺血性脑病患者血NO/NOS和TNF测定的临床意义

目的　探讨了新生儿缺氧缺血性脑病患者血清 NO/ NOS和 TNF含量及其临床意义。方法　应用生化法和放射免疫分析法对 38例新生儿缺氧缺血性脑病患者进行了血清 NO/ NOS和 TNF含量检测 ,并与 35名正常新生儿作比较。结果　血清患儿组血清 NO水平低于正常人组 (P<0 .0 1 ) ,而 NOS和 TNF水平则显著高于正常人组(P<0 .0 1 )。结论　测定血清 NO/ NOS和 TNF含量与患儿的危重程度发生发展、预后有关     

双苯氟嗪对脑缺血再灌注损伤后脑组织及血清中NO、NO S、iNO S的影响

目的研究双苯氟嗪(D ipfluzine,D ip)对大鼠脑缺血再灌注损伤模型的脑组织及血清中一氧化氮(NO)含量、一氧化氮合酶(NOS)及诱导型一氧化氮合酶(iNOS)活性的影响。方法选用♂SD大鼠,随机分为7组:假手术组、缺血再灌注组、溶剂对照组、D ip(0.5、1.0、和2.0 mg.kg-1)治疗组、氟桂利嗪(F lunarizine,F lu)1.0 mg.kg-1阳性对照组。采用改良的Pu lsinelli四动脉结扎法制备大鼠全脑缺血15m in再灌注24 h模型,并于再灌注开始时尾静脉注射给药。分别观察各组大鼠脑海马CA1区神经元形态学变化以及脑组织和血清中NO含量和NOS、iNOS活性的变化。结果形态学观察可见:假手术组细胞排列整齐、紧密,胞核大而圆,透明,核仁清晰可见,缺血再灌组和溶剂对照组细胞排列松散,胞体缩小,核不规则。双苯氟嗪和氟桂利嗪均可明显改善这种损伤性改变。与假手术组相比,缺血再灌注组和溶剂对照组脑组织和血清中NO含量和NOS、iNOS活性明显升高;与溶剂对照组相比,D ip 1.0 mg.kg-1组、D ip 2.0 mg.kg-1组及F lu组脑组织和血清中NO的含量、iNOS活力、以及脑组织中NOS活力均明显降低。结论双苯氟嗪可降低NOS、iNOS活性,减少NO含量,减轻神经元损伤程度,具有脑保护作用。     

5-脂氧合酶抑制剂zileuton对大鼠局灶性脑缺血/再灌注损伤的保护作用

目的观察5-脂氧合酶抑制剂zileuton对大鼠局灶性脑缺血/再灌注损伤的保护作用。方法线栓法阻塞大鼠大脑中动脉2 h/再灌注24 h,观察zileuton 10、50 mg.kg-1对脑梗塞体积、脑组织髓过氧化物酶(MPO)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-PX)、一氧化氮(NO)、一氧化氮合酶(NOS)含量的影响。结果zileuton 10、50 mg.kg-1均能明显缩小脑梗死灶,降低NOS活性及NO含量,高剂量组亦可降低脑组织MDA含量、增加GSH-PX活性、缓解MPO升高。结论zileuton对大鼠局灶性脑缺血/再灌注损伤有保护作用。     

Modulation of prostaglandin biosynthesis by nitric oxide and nitric oxide donors

The biosynthesis and release of nitric oxide (NO) and prostaglandins (PGs) share a number of similarities. Two major forms of nitric-oxide synthase (NOS) and cyclooxygenase (COX) enzymes have been identified to date. Under normal circumstances, the constitutive isoforms of these enzymes (constitutive NOS and COX-1) are found in virtually all organs. Their presence accounts for the regulation of several important physiological effects (e.g. antiplatelet activity, vasodilation, and cytoprotection). On the other hand, in inflammatory setting, the inducible isoforms of these enzymes (inducible NOS and COX-2) are detected in a variety of cells, resulting in the production of large amounts of proinflammatory and cytotoxic NO and PGs. The release of NO and PGs by the inducible isoforms of NOS and COX has been associated with the pathological roles of these mediators in disease states as evidenced by the use of selective inhibitors. An important link between the NOS and COX pathways was made in 1993 by Salvemini and coworkers when they demonstrated that the enhanced release of PGs, which follows inflammatory mechanisms, was nearly entirely driven by NO. Such studies raised the possibility that COX enzymes represent important endogenous "receptor" targets for modulating the multifaceted roles of NO. Since then, numerous papers have been published extending the observation across various cellular systems and animal models of disease. Furthermore, other studies have highlighted the importance of such interaction in physiology as well as in the mechanism of action of drugs such as organic nitrates. More importantly, mechanistic studies of how NO switches on/off the PG/COX pathway have been undertaken and additional pathways through which NO modulates prostaglandin production unraveled. On the other hand, NO donors conjugated with COX inhibitors have recently found new interest in the understanding of NO/COX reciprocal interaction and potential clinical use. The purpose of this article is to cover the advances which have occurred over the years, and in particular, to summarize experimental data that outline how the discovery that NO modulates prostaglandin production has impacted and extended our understanding of these two systems in physiopathological events.     

Feedback inhibition of nitric oxide synthase activity by nitric oxide.

1. A murine macrophage cell line, J774, expressed nitric oxide (NO) synthase activity in response to interferon-gamma (IFN-gamma, 10 u ml-1) plus lipopolysaccharide (LPS, 10 ng ml-1). The enzyme activity was first detectable 6 h after incubation, peaked at 12 h and became undetectable after 48 h. 2. The decline in the NO synthase activity was not due to inhibition by stable substances secreted by the cells into the culture supernatant. 3. The decline in the NO synthase activity was significantly slowed down in cells cultured in a low L-arginine medium or with added haemoglobin, suggesting that NO may be involved in a feedback inhibitory mechanism. 4. The addition of NO generators, S-nitroso-acetyl-penicillamine (SNAP) or S-nitroso-glutathione (GSNO) markedly inhibited the NO synthase activity in a dose-dependent manner. The effect of NO on the enzyme was not due to the inhibition of de novo protein synthesis. 5. SNAP directly inhibited the inducible NO synthase extracted from activated J774 cells, as well as the constitutive NO synthase extracted from the rat brain. 6. The enzyme activity of J774 cells was not restored after the removal of SNAP by gel filtration, suggesting that NO inhibits NO synthase irreversibly.     

Influence of nitric oxide derived from neuronal nitric oxide synthase on glomerular filtration

The neuronal isoform of nitric oxide synthase (nNOS) has been localized to specific regions of the kidney, including the thick ascending limb of the loop of Henle and the macula densa. Because of this discrete localization in the renal cortex, nitric oxide (NO) produced by nNOS has been suggested to play an important role in the regulation of macula densa-mediated arteriole tone and therefore could play an important role in the regulation of whole-kidney glomerular filtration rate (GFR). We hypothesized that selective blockade of nNOS would decrease GFR. Renal hemodynamics were measured before and after acute selective blockade of nNOS by 50 mg/kg 7-nitroindazole (7-NI) in anesthetized rats. Administration of 7-NI had no significant effect on basal blood pressure (from 105 +/- 3 to 101 +/- 2 mm Hg), renal blood flow [from 6.08 +/- 0.39 to 6.31 +/- 0.33 ml/min/gram of kidney weight (gkw)], or total renal vascular resistance (from 18.1 +/- 1.6 to 16.4 +/- 1.0 mm Hg/ml/min/gkw) but decreased GFR by 26% (from 1.36 +/- 0.15 to 1.00 +/- 0.13 ml/min/gkw; p < 0.02), urinary flow rate by 28% (from 24.7 +/- 1.8 to 17.8 +/- 2.2 microl/min; p < 0.05), and sodium excretion by 22% (from 5.55 +/- 0.53 to 4.30 +/- 0.52 microEq/min; p < 0.05). However, fractional sodium excretion was not changed by nNOS inhibition. There were no such changes in vehicle-treated time controls. We conclude that, in the renal cortex, NO produced by nNOS plays an important role in the regulation of whole-kidney GFR and excretion in normal, sodium-replete rats.     

Mitochondrial nitric oxide synthase

Mitochondria produce nitric oxide (NO) through a Ca(2+)-sensitive mitochondrial NO synthase (mtNOS). The NO produced by mtNOS regulates mitochondrial oxygen consumption and transmembrane potential via a reversible reaction with cytochrome c oxidase. The reaction of this NO with superoxide anion yields peroxynitrite, which irreversibly modifies susceptible targets within mitochondria and induces oxidative and/or nitrative stress. In this article, we review the current understanding of the roles of mtNOS as a crucial biochemical regulator of mitochondrial functions and attempt to reconcile apparent discrepancies in the literature on mtNOS.     

Role of inducible nitric oxide synthase-derived nitric oxide in lipopolysaccharide plus interferon-gamma-induced pulmonary inflammation

Exposure of mice to lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma) increases nitric oxide (NO) production, which is proposed to play a role in the resulting pulmonary damage and inflammation. To determine the role of inducible nitric oxide synthase (iNOS)-induced NO in this lung reaction, the responses of inducible nitric oxide synthase knockout (iNOS KO) versus C57BL/6J wild-type (WT) mice to aspirated LPS + IFN-gamma were compared. Male mice (8-10 weeks) were exposed to LPS (1.2 mg/kg) + IFN-gamma (5000 U/mouse) or saline. At 24 or 72 h postexposure, lungs were lavaged with saline and the acellular fluid from the first bronchoalveolar lavage (BAL) was analyzed for total antioxidant capacity (TAC), lactate dehydrogenase (LDH) activity, albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and AM zymosan-stimulated chemiluminescence (AM-CL). Pulmonary responses 24 h postexposure to LPS + IFN-gamma were characterized by significantly decreased TAC, increased BAL AMs and PMNs, LDH, albumin, TNF-alpha, and MIP-2, and enhanced AM-CL to the same extent in both WT and iNOS KO mice. Responses 72 h postexposure were similar; however, significant differences were found between WT and iNOS KO mice. iNOS KO mice demonstrated a greater decline in total antioxidant capacity, greater BAL PMNs, LDH, albumin, TNF-alpha, and MIP-2, and an enhanced AM-CL compared to the WT. These data suggest that the role of iNOS-derived NO in the pulmonary response to LPS + IFN-gamma is anti-inflammatory, and this becomes evident over time.     

Biochemical aspects of nitric oxide

Nitric oxide (NO), a free radical molecule, produced by NO synthase (NOS) in the body exerts a number of pathophysiological actions due to its chemical reactivity. Low amounts of NO (nM) normally produced by constitutive NOS play a critical role in different physiological events such as vasodilation and neurotransmission. Higher amounts of NO ( micro M) locally and spatially produced by inducible NOS during inflammation act as double-edged sword exerting either beneficial or detrimental effects. Recently, new vision on the biological role of NO has been proposed based on the possible cross-talk between constitutive and inducible NOS. Accordingly, normally produced low amounts of NO may be involved in the regulation of NF-kappaB activation and successively the expression of inducible NOS. Under normal conditions NF-kappaB activation is suppressed by low amounts of NO. Under conditions in which massive amounts of NO produced by inducible NOS act detrimentally, NO-elicited down-regulation of NF-kappaB activation is compromised due to the drop in NO at the early phase of inflammation caused by inactivation of constitutive NOS. Any treatment which counterparts the drop in NO, therefore, may present a new approach either in preventing or in treating inflammatory diseases.     

Role of inducible nitric oxide synthase-derived nitric oxide in silica-induced pulmonary inflammation and fibrosis

Inhalation of crystalline silica can produce lung inflammation and fibrosis. Inducible nitric oxide synthase (iNOS)-derived nitric oxide (NO) is believed to be involved in silica-induced lung disease. To investigate the role of iNOS-derived NO in this disease, the responses of iNOS knockout (KO) versus C57Bl/6J wild-type (WT) mice to silica were compared. Male mice (8-10 wk old, mean body weight 24.0 g) were anesthetized and exposed, by aspiration, to silica (40 mg/kg) or saline. At 24 h and 42 d postexposure, lungs were lavaged with saline. The first bronchoalveolar lavage (BAL) fluid supernatant was analyzed for lactate dehydrogenase (LDH) activity, levels of albumin, tumor necrosis factor-alpha (TNF-alpha), and macrophage inflammatory protein-2 (MIP-2), as well as total antioxidant capacity (TAC). The cellular fraction of the total BAL was used to determine alveolar macrophage (AM) and polymorphonuclear leukocyte (PMN) counts, and zymosanstimulated AM chemiluminescence (AM-CL). In separate mice, lung histopathological changes were evaluated 42 d postexposure. Acute (24-h) silica exposure decreased AMs, increased PMNs, increased LDH activity and levels of albumin, TNF-alpha, and MIP-2 in BAL fluid, and enhanced AM-CL in both iNOS KO and WT mice. However, iNOS KO mice exhibited less AM activation (defined as increased AM-CL and decreased AM yield) than WT. Furthermore, TAC following acute silica decreased in WT but was maintained in iNOS KO mice. Pulmonary reactions to subchronic (42 d) silica exposure were similar to acute. However, histopathological and BAL fluid indices of lung damage and inflammation, AM activation, and lung hydroxyproline levels were significantly less in iNOS KO compared to WT mice. These results suggest that iNOS-derived NO contributes to the pathogenesis of silica-induced lung disease in this mouse model.     

Drugs that activate specific nitric oxide sensitive guanylyl cyclase isoforms independent of nitric oxide release

Nitric oxide (NO) releasing drugs have helped patients suffering from angina pectoris for more than a century. In the 1970s NO-sensitive guanylyl cyclase was identified as the target of NO. Since then, three different isoforms of the enzyme have been identified. All NO-releasing drugs act by binding of NO to the prosthetic heme group common to all three isoforms. They thus act all as isoform-unspecific substances. This review addresses recently developed drugs that activate NO-sensitive guanylyl cyclase independent of NO-release. They have great potential in the treatment of angina pectoris, hypertension and erectile dysfunction. The molecular target has been validated by the successful clinical use of NO-releasing drugs for more than a century. At the same time the mode of action of these drugs is entirely new. The development of highly isoform-specific derivatives with distinct pharmacological profiles is now an open possibility with great potential.     

Co-induction of nitric oxide synthase and cyclo-oxygenase: interactions between nitric oxide and prostanoids.

1. Lipopolysaccharide (LPS) co-induces nitric oxide synthase (iNOS) and cyclo-oxygenase (COX-2) in J774.2 macrophages. Here we have used LPS-activated J774.2 macrophages to investigate the effects of exogenous or endogenous nitric oxide (NO) on COX-2 in both intact and broken cell preparations. NOS activity was assessed by measuring the accumulation of nitrite using the Griess reaction. COX-2 activity was assessed by measuring the formation of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) by radioimmunoassay. Western blot analysis was used to determine the expression of COX-2 protein. We have also investigated whether endogenous NO regulates the activity and/or expression of COX in vivo by measuring NOS and COX activity in the lung and kidney, as well as release of prostanoids from the perfused lung of normal and LPS-treated rats. 2. Incubation of cultured murine macrophages (J774.2 cells) with LPS (1 microgram ml-1) for 24 h caused a time-dependent accumulation of nitrite and 6-keto-PGF1 alpha in the cell culture medium which was first significant after 6 h. The formation of both 6-keto-PGF1 alpha and nitrite elicited by LPS was inhibited by cycloheximide (1 microM) or dexamethasone (1 microM). Western blot analysis showed that J774.2 macrophages contained COX-2 protein after LPS administration, whereas untreated cells contained no COX-2. 3. The accumulation of 6-keto-PGF1 alpha in the medium of LPS-activated J774.2 macrophages was concentration-dependently inhibited by chronic (24 h) exposure to sodium nitroprusside (SNP; 1-1000 microM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Photosensitive precursors to nitric oxide

The photochemistry and use of recently developed photosensitive precursors to nitric oxide (NO) are reviewed. As "caged NO" donors these precursors are able to deliver NO in a spatially and temporally controllable manner. These properties have made such precursors useful in applications in biology and medicine, especially in elucidating neurophysiological roles of NO and in new cancer therapies.