Increase in oxidized NO products and reduction in oxidized glutathione in cerebrospinal fluid from patients with sporadic form of amyotrophic lateral sclerosis

To determine the role of free radical mechanisms in the pathogenesis of amyotrophic lateral sclerosis (ALS), cerebrospinal fluid concentrations of oxidized nitric oxide (NO) products (nitrite and nitrate) and reduced and oxidized forms of glutathione (GSH and GSSG, respectively) were compared between patients with the sporadic form of ALS (SALS) and controls. In the SALS patients, the nitrate levels were significantly higher (by 73%) in contrast to remarkably lower GSSG/GSH ratio, approximately 3-fold, compared to controls. These results suggest that NO production or oxidation is activated in SALS patients, leading to a decrease in superoxide radicals to oxidize GSH. The subsequent generation of a highly reactive anion, peroxynitrite, may play a causal role in the pathogenesis of SALS.     

Cell signalling-mediating insulin increase of mRNA expression for cationic amino acid transporters-1 and -2 and membrane hyperpolarization in human umbilical vein endothelial cells

Insulin induces vasodilatation in human subjects and increases l-arginine transport and NO synthesis in human umbilical vein endothelial cells (HUVEC). Cell signalling events associated with insulin effects on activity and mRNA expression of the human cationic amino acid transporters 1 (hCAT-1) and 2B (hCAT-2B) are unknown. l-Arginine transport and eNOS activity were determined in HUVEC exposed to insulin. mRNA levels for hCAT-1, hCAT-2B and eNOS were quantitated by real time RT-PCR and endothelial NO synthase (eNOS) protein was identified by Western blot analysis. Intracellular Ca²⁺, l-arginine and l-citrulline levels, l-[³H]citrulline formation from l-[³H]arginine, cGMP formation, nitrite level, ATP release and membrane potential were determined. Insulin increased l-arginine transport and the mRNA levels for hCAT-1 and hCAT-2B and eNOS expression and activity. Insulin also induced membrane hyperpolarization and increased intracellular Ca²⁺, l-[³H]citrulline, cGMP and nitrite formation. Insulin-mediated stimulation of the l-arginine/NO pathway is thus associated with increased hCAT-1 and hCAT-2B mRNA, and eNOS expression, via mechanisms involving membrane hyperpolarization, mitogen-activated protein kinases p42 and p44, phosphatidylinositol 3-kinase, NO and protein kinase C. We have characterized a cell signalling pathway by which hyperinsulinaemia could lead to vasodilatation in human subjects, and which could have implications in patients in whom plasma insulin levels are altered, such as in diabetes mellitus.     

高压氧抑制一氧化氮生成改善缺血性脑细胞凋亡

目的探讨高压氧对脑缺血再灌流脑皮层一氧化氮(NO)生成的影响及其对脑细胞的保护作用。方法采用沙土鼠双侧颈总动脉夹闭30min再灌流模型。用电化学及免疫细胞化学方法检测脑皮层一氧化氮生成、一氧化氮合酶(NOS)表达及神经细胞凋亡。结果缺血再灌流期沙土鼠脑皮层中NO的含量显著增加，3型NOS均有表达，缺血再灌流第2d，iNOS的表达最为明显，同时NO的生成达到高峰。缺血再灌流第1、2、3d，沙土鼠脑皮层均可见凋亡细胞，以第2、3d更为明显。高压氧暴露能明显抑制iNOS表达，减少NO生成，减轻神经细胞凋亡。结论高压氧能抑制沙土鼠脑缺血再灌流期脑皮层NO生成，减轻神经细胞凋亡，从而起到脑保护作用。     

Nitric oxide mediates intestinal hyperaemic responses to intraluminal bile-oleate

It has long been recognized that intestinal blood flow increases at mealtimes. Mesenteric hyperaemia is also evoked by activation of sensory peptidergic nerves. Our studies explored the possible role of endogenous nitric oxide (NO) in the rat intestinal vasodilator response to luminal instillation of an oleic acid plus bile mixture before and after acute intrajejunal instillation of capsaicin and after chronic pretreatment with capsaicin. In anaesthetized rats we measured jejunal blood flow (BF) with an ultrasonic Doppler flowmeter and systemic arterial pressure (AP) with a pressure transducer. Intestinal perfusion with 80 mM oleic acid in bile increased BF by 98±12%. Instillation of 4 mg of capsaicin into the jejunal lumen initially increased BF by 42±9% but was followed by vasoconstriction. Inhibition of NO synthase with 25 mg/kg i.v. N-nitro-L-arginine (L-NNA) decreased BF by 27±5% and increased AP by 37±11%. After treatment with L-NNA and after acute and chronic administration of capsaicin, the bile-oleate-induced maximal increases in BF above control levels were 42±7%, 65±12%, and 58±8%, respectively. The observed inhibitory effect of L-NNA on the intestinal hyperaemic response to the bile-oleate mixture was reversed by pretreatment with L-arginine (100 mg/kg i.V.). In capsaicin pretreated rats the subsequent bile-oleate-induced hyperaemia was reduced in magnitude but the inhibitory effects of L-NNA were proportionately the same as in animals not receiving capsaicin. These findings support the hypothesis that NO is involved with bile-oleate-induced mesenteric hyperaemia.     

Inhibition of nitric oxide synthase increases synaptophysin mRNA expression in the hippocampal formation of rats

Synaptophysin is a protein involved in the biogenesis of synaptic vesicles and budding. It has been used as an important tool to investigate plastic effects on synaptic transmission. Nitric oxide (NO) can influence plastic changes in specific brain regions related to cognition and emotion. Experimental evidence suggests that NO and synaptophysin are co-localized in several brain regions and that NO may change synaptophysin expression. Therefore, the aim of the present work was to investigate if inhibition of NO formation would change synaptophysin mRNA expression in the hippocampal formation. Male Wistar rats received single or repeated (once a day for 4 days) i.p. injections of saline or l-nitro-arginine (l-NOARG, 40 mg/kg), a non-selective inhibitor of nitric oxide synthase (NOS). Twenty-four hours after the last injection the animals were sacrificed and their brains removed for ‘in situ’ hybridization study using ³⁵S-labeled oligonucleotide probe complementary to synaptophysin mRNA. The results were analyzed by computerized densitometry. Acute administration of l-NOARG induced a significant (p < 0.05, ANOVA) increase in synaptophysin mRNA expression in the dentate gyrus, CA1 and CA3. The effect disappeared after repeated drug administration. No change was found in the striatum, cingulated cortex, substantia nigra or nucleus accumbens. These results reinforce the proposal that nitric oxide is involved in plastic events in the hippocampus.     

心肌缺血/再灌注前处置时血浆一氧化氮的变化及意义

目的：在兔心肌缺血／再灌注前处置模型的基础上，了解NO在心肌缺血前处置中所起的作用及意义。方法：采用免麻醉后开胸结扎左冠状动脉降支，反复结扎（缺血）10分钟，放开（再灌）5分钟，最后结扎30分钟再灌20分钟造成缺血／再灌注前处置模型后，对比观察了各组动物血浆中NO、TXB2、6－K－PGF1α、SOD和MDA浓度的变化，以及各组动物球结膜微循环及心肌病理学的变化。结果：前处置组血浆NO、6－K－PGF1α、SOD浓度显著高于缺血／再灌注组，而MDA、TXB2浓度明显低于缺血／再灌注组。前处置组心肌超微结构损伤明显轻于缺血／再灌注组，球结膜微循环基本正常。结论：心肌缺血前处置可增加心血管内皮细胞合成NO，而NO具有减轻心肌缺血／再灌注损伤、改善微循环障碍的作用。     

Dopamine and serotonin: influences on male sexual behavior

Steroid hormones regulate sexual behavior primarily by slow, genomically mediated effects. These effects are realized, in part, by enhancing the processing of relevant sensory stimuli, altering the synthesis, release, and/or receptors for neurotransmitters in integrative areas, and increasing the responsiveness of appropriate motor outputs. Dopamine has facilitative effects on sexual motivation, copulatory proficiency, and genital reflexes. Dopamine in the nigrostriatal tract influences motor activity; in the mesolimbic tract it activates numerous motivated behaviors, including copulation; in the medial preoptic area (MPOA) it controls genital reflexes, copulatory patterns, and specifically sexual motivation. Testosterone increases nitric oxide synthase in the MPOA; nitric oxide increases basal and female-stimulated dopamine release, which in turn facilitates copulation and genital reflexes. Serotonin (5-HT) is primarily inhibitory, although stimulation of 5-HT(2C) receptors increases erections and inhibits ejaculation, whereas stimulation of 5-HT(1A) receptors has the opposite effects: facilitation of ejaculation and, in some circumstances, inhibition of erection. 5-HT is released in the anterior lateral hypothalamus at the time of ejaculation. Microinjections of selective serotonin reuptake inhibitors there delay the onset of copulation and delay ejaculation after copulation begins. One means for this inhibition is a decrease in dopamine release in the mesolimbic tract.     

老年Ⅱ型糖尿病患者血清NO水平与肾功能变化的相关性研究

目的探讨一氧化氮(NO)在老年Ⅱ型糖尿病肾病发病过程中的变化规律及其与肾功能的关系。方法采用Griess法检测48例Ⅱ型DM病人血清NO值在水平及与肾功能有关的指标,并与17例正常人进行比较,结果血清NO值在正常尿蛋白(DMI)组(88.86±9.61umol/l)和微量尿蛋白(DMII)组(90.00±17.94umol/l)明显高于对照组(56.70±9.53umol/l)(P＜0.01),至临床肾病期血浆NO浓度明显降低(63.25±8.64umol/l)(P＞0.05);NO与BUN、BCR呈负相关,而与CCR呈正相关。结论血清NO水平的动态变化与Ⅱ型DM肾病的发生、发展有密切联系。     

天麻素对缺血再灌注损伤星形胶质细胞的保护作用及其对一氧化氮合成酶活性的影响

观察天麻素对脑缺血再灌注损伤星形胶质细胞胶原纤维酸性蛋白 (GFAP)表达、乳酸脱氢酶(LDH)漏出量以及一氧化氮合成酶 (NOS)活性的影响。结果 :天麻素大、小剂量组GFAP纤维样改变减轻 ,强阳性反应细胞数减少 ;LDH漏出量下降 ;NOS活性减弱。提示 :天麻素对模拟脑缺血再灌注损伤星形胶质细胞有良好的保护作用 ,其途径之一可能是通过抑制NOS活性的反应性增强来实现的。     

心达康对老年高血压病人血清一氧化氮的影响

目的：观察老年高血压一氧化氮（NO）的水平变化及心达康对其的影响。方法：应用比色法测定52例老年高血压病人和30例正常人的血清（NO）水平,其中20例在应用心达康,26例用非洛地平治疗2－4周后,复查血清（NO）水平。结果：老年高血压病人血清（NO）水平较对照组明显降低（P＜0．01）,Ⅱ-Ⅲ级病人明显低于I级病人（P＜0．01）,经心达康治疗后血清NO水平明显升高（P＜0．01）,非洛地平治疗后血清NO无明显变化（P＞0．05）。结论：老年高血压病人体内（NO）水平显降低,且随病情加重而更为显。心达康治疗后（NO）水平明显升高。