糖尿病性勃起功能障碍多因素发病机制研究

从神经、血管、代谢、离子通道等多个角度出发,研究糖尿病性勃起功能障碍(DMED)的发病机制,为开展DMED的综合治疗临床研究提供前期研究基础.成年雄性SD大鼠50只,随机取35只大鼠用于制作糖尿病模型,其余大鼠作为正常对照.饲养8周后,用阿朴吗啡法筛选DMED大鼠,用电刺激勃起神经测定海绵体内压(ICP)方法评价勃起功能.取正常组和DMED组大鼠的阴茎海绵体组织,分成若干份,用免疫组化法测定海绵体组织一氧化氮合酶(NOS)的3种亚型(nNOS,eNOS,iNOS)的变化;用Western Blot法测定神经生长因子(NGF)在海绵体组织的表达差异;用放射免疫法测定海绵体组织血管紧张素II(AngII)含量差异;用Western Blot法测定血管内皮生长因子(VEGF)和缝隙连接蛋白Connexin-43含量差异.与正常对照组相比,DMED大鼠ICP测定值明显降低;海绵体组织中nNOS、eNOS表达明显降低,而iNOS表达明显增加;NGF蛋白表达明显增加;血管紧张素II水平显著升高;VEGF蛋白表达明显减少;Connexin-43蛋白表达减少.以上试验结果说明DMED发病机制复杂,与神经、血管、代谢、离子通道等均有关.提示在今后临床治疗研究和实践中,应该从各个角度出发,针对多因素发病机制,采用综合治疗的方法,以提高疗效.     

不同强度运动对大鼠肾脏皮质区 NOS、Bcl-2/Bax表达的影响

采用跑台训练方式,建立了大鼠有氧运动和疲劳运动模型,运用免疫组织化学SABC法研究不同运动强度对大鼠肾脏皮质区nNOSi、NOS、eNOS和Bcl-2/Bax表达的影响.结果显示,与对照组比较,有氧训练组nNOSi、NOS、eNOS分别升高了9.1%、11.1%(P<0.05)、33.3%(P<0.05);疲劳训练组分别升高了18.2%、22.2%(P<0.05)、66.7%(P<0.05);Bcl-2/Bax的表达在有氧运动组明显升高(升高了135.0%),在疲劳运动组略有降低(降低了8.8%).不同强度运动大鼠肾脏皮质区NOS的表达均有升高,显示运动诱导NO的生成增加;Bcl-2/Bax在肾脏皮质区的表达受运动强度的影响显著,大强度运动可引起Bax显著表达,Bcl-2表达减少,Bax/Bcl-2的比率增加,表明大强度运动可促进大鼠肾脏皮质区的细胞凋亡,且与NO大量生成有关.     

S-glutathionylation uncouples eNOS and regulates its cellular and vascular function

Endothelial nitric oxide synthase (eNOS) is critical in the regulation of vascular function, and can generate both nitric oxide (NO) and superoxide (O(2)(?-)), which are key mediators of cellular signalling. In the presence of Ca(2+)/calmodulin, eNOS produces NO, endothelial-derived relaxing factor, from l-arginine (l-Arg) by means of electron transfer from NADPH through a flavin containing reductase domain to oxygen bound at the haem of an oxygenase domain, which also contains binding sites for tetrahydrobiopterin (BH(4)) and l-Arg. In the absence of BH(4), NO synthesis is abrogated and instead O(2)(?-) is generated. While NOS dysfunction occurs in diseases with redox stress, BH(4) repletion only partly restores NOS activity and NOS-dependent vasodilation. This suggests that there is an as yet unidentified redox-regulated mechanism controlling NOS function. Protein thiols can undergo S-glutathionylation, a reversible protein modification involved in cellular signalling and adaptation. Under oxidative stress, S-glutathionylation occurs through thiol-disulphide exchange with oxidized glutathione or reaction of oxidant-induced protein thiyl radicals with reduced glutathione. Cysteine residues are critical for the maintenance of eNOS function; we therefore speculated that oxidative stress could alter eNOS activity through S-glutathionylation. Here we show that S-glutathionylation of eNOS reversibly decreases NOS activity with an increase in O(2)(?-) generation primarily from the reductase, in which two highly conserved cysteine residues are identified as sites of S-glutathionylation and found to be critical for redox-regulation of eNOS function. We show that eNOS S-glutathionylation in endothelial cells, with loss of NO and gain of O(2)(?-) generation, is associated with impaired endothelium-dependent vasodilation. In hypertensive vessels, eNOS S-glutathionylation is increased with impaired endothelium-dependent vasodilation that is restored by thiol-specific reducing agents, which reverse this S-glutathionylation. Thus, S-glutathionylation of eNOS is a pivotal switch providing redox regulation of cellular signalling, endothelial function and vascular tone.     

大鼠急性局灶性脑缺血再灌注NO含量和NOS活性的变化及7-NI对其影响的实验研究

目的探讨一氧化氮和神经元型一氧化氮合酶是否参与了急性脑缺血再灌注的发病机制.方法采用栓线法复制大鼠大脑中动脉阻塞模型,观察血清和脑组织NO含量和NOS活性的变化及神经元型一氧化氮合酶抑制剂7-硝基吲唑对再灌注期间两者的影响.结果脑缺血45 min再灌注2 h后血清及脑组织中NOS活性及NO含量增加,再灌注8 h达高峰.7-NI能显著抑制再灌注期间血清及脑组织中NOS的活性及NO的含量.结论 NO和nNOS在急性局灶性脑缺血再灌注的过程中起着重要的作用.     

晚期糖基化终产物对大鼠阴茎海绵体组织中一氧化氮含量及其合成酶活性的影响

通过观察大鼠阴茎海绵体组织中晚期糖基化终产物(AGEs)含量的变化对一氧化氮(NO)含量及其合成酶(NOS)活性的影响,探讨AGEs在糖尿病性勃起功能障碍(DMED)发生发展中的作用.成年雄性SD大鼠60只,随机取40只用于制作糖尿病模型,造模成功的大鼠分为两组:糖尿病(DM)组和糖尿病 氨基胍给药(DM AG)组;另20只大鼠亦分为两组:正常对照(CONTROL)组和正常对照 氨基胍给药(CONTROL AG)组;氨基胍(AG)给药组大鼠造模后即在其饮水中按1 g/L剂量加入AG.饲养8周后取各组大鼠阴茎海绵体组织,匀浆后检测AGE-肽(AGE-P)含量、NO含量及各型NOS酶活性.DM组阴茎海绵体组织中AGE-P含量、NO含量及诱导型NOS(iNOS)活性明显高于CONTROL组(P＜0.05),而结构型NOS(cNOS)活性则明显低于后者(P＜0.05),而AG则明显减少了DM大鼠阴茎海绵体组织中AGE-P、NO的生成和减弱了iNOS活性,增强了cNOS活性;CONTROL组与CONTROL AG组间比较在各项指标上则无明显差异(P＞0.05).糖尿病状态下AGEs可以引起大鼠阴茎海绵体组织中cNOS活性减弱,iNOS活性增强,过量的NO生成,可能引起阴茎组织细胞的凋亡,导致阴茎勃起功能的损伤.     

NOS在甲状腺功能低下小鼠脑中含量变化的研究

本文研究了甲状腺激素减少时,小鼠的大脑、小脑、海马、嗅脑等脑组织中一氧化氮合酶（NOS）含量的变化.采用丙硫氧嘧啶（PTU）持续灌注20日龄左右雌性昆明小鼠造成甲减模型.采用NOS的生化测定法检测甲减小鼠的大脑、小脑、嗅脑、海马等中的NOS含量;检测指标包括组织中总一氧化氮合酶（TNOS）活性,以及诱导型一氧化氮合酶（iNOS）及结构型一氧化氮合酶（cNOS）两种分型酶的活性.生化测定法显示,甲状腺功能低下小鼠NOS含量与对照组比较在大脑、小脑和嗅脑中均出现了下降,cNOS在大脑、小脑、海马、嗅脑部位也均出现了下调.而iNOS含量在甲状腺功能低下小鼠的大脑、小脑、海马、嗅脑中却出现了上调.由此可得出,甲状腺激素的分泌异常会造成NOS含量的异常,NO信号系统可能参与甲状腺激素缺乏所致的脑损害过程.     

Effects of niacin on nitric oxide synthase expression in rat lungs exposed to silica

The aim of this study was to evaluate the effects of niacin in diet on the expression of nitric oxide synthase (NOS) in rat lungs of the animal model of silicosis established by direct tracheal instillation of silica particles into rat lungs surgically. The niacin concentration in serum was analyzed by high performance liquid chromatography (HPLC). The expression of inducible nitric oxide synthase (iNOS) protein in paraffin-embedded lung sections was determined by streptavidin/peroxidase (SP) staining. Quantitative analysis by Image-Pro Plus was also performed on the expression of iNOS. The results showed that niacin concentration in serum of the niacin-treated rats was significantly higher than that in the control and silica-treated rats. After 7 days of silica instillation, iNOS integrated optical density (IOD) in rat lungs and total NOS and iNOS activities in bronchoalveolar lavage fluid (BALF) in silica-treated rats rose by 273420.75, 2.61 units/mL and 1.89 units/mL respectively, when compared with those in the control rats. Niacin treatment significantly reduced silica-induced iNOS IOD in rat lung tissues and total NOS and iNOS activities in BALF supernatant by 248292.35, 1.50 units/mL and 0.91 units/mL, respectively, as compared with those in silica-treated rats. Therefore, niacin can effectively attenuate the pathological expression of NOS in rat lung tissues induced by silica particles.     

Tumour maintenance is mediated by eNOS

Tumour cells become addicted to the expression of initiating oncogenes like Ras, such that loss of oncogene expression in established tumours leads to tumour regression. HRas, NRas or KRas are mutated to remain in the active GTP-bound oncogenic state in many cancers. Although Ras activates several proteins to initiate human tumour growth, only PI3K, through activation of protein kinase B (PKB; also known as AKT), must remain activated by oncogenic Ras to maintain this growth. Here we show that blocking phosphorylation of the AKT substrate, endothelial nitric oxide synthase (eNOS or NOS3), inhibits tumour initiation and maintenance. Moreover, eNOS enhances the nitrosylation and activation of endogenous wild-type Ras proteins, which are required throughout tumorigenesis. We suggest that activation of the PI3K-AKT-eNOS-(wild-type) Ras pathway by oncogenic Ras in cancer cells is required to initiate and maintain tumour growth.     

新鲜冰冻血浆（FFP）通过AMPK/Akt/eNOS通路促肺内皮细胞一氧化氮释放及机制研究

探讨新鲜冰冻血浆(FFP)对人肺正常微血管内皮细胞(HPMECs)一氧化氮(NO)释放的影响及其机制.采用NO/Nitrite/Nitrate分析法检测了体外培养内皮细胞HPMECs经FFP处理后不同时间点细胞上清NO含量.结果显示:与培养基空白对照组相比,FFP显著增加内皮细胞NO生成;采用磷酸化蛋白激酶抗体芯片和免疫印迹方法筛选和鉴定FFP处理后内皮细胞相关蛋白激酶磷酸化,结果为FFP显著增加内皮细胞AMPKα1,Akt1和eNOS蛋白的磷酸化.进一步分别采用Compound C(AMPK抑制剂),LY294002(PI3K/Akt抑制剂)或L-NAME(NOS抑制剂)预处理细胞,阻挡AMPKα1/Akt1/eNOS信号转导通路.结果显示上述三种抑制剂均能抑制FFP诱导eNOS激活和NO生成,表明AMPKα1/Akt1/eNOS信号转导通路介导FFP诱导NO分泌参与血管保护.     

Nitric oxide regulates the heart by spatial confinement of nitric oxide synthase isoforms

Subcellular localization of nitric oxide (NO) synthases with effector molecules is an important regulatory mechanism for NO signalling. In the heart, NO inhibits L-type Ca2+ channels but stimulates sarcoplasmic reticulum (SR) Ca2+ release, leading to variable effects on myocardial contractility. Here we show that spatial confinement of specific NO synthase isoforms regulates this process. Endothelial NO synthase (NOS3) localizes to caveolae, where compartmentalization with beta-adrenergic receptors and L-type Ca2+ channels allows NO to inhibit beta-adrenergic-induced inotropy. Neuronal NO synthase (NOS1), however, is targeted to cardiac SR. NO stimulation of SR Ca2+ release via the ryanodine receptor (RyR) in vitro, suggests that NOS1 has an opposite, facilitative effect on contractility. We demonstrate that NOS1-deficient mice have suppressed inotropic response, whereas NOS3-deficient mice have enhanced contractility, owing to corresponding changes in SR Ca2+ release. Both NOS1-/- and NOS3-/- mice develop age-related hypertrophy, although only NOS3-/- mice are hypertensive. NOS1/3-/- double knockout mice have suppressed beta-adrenergic responses and an additive phenotype of marked ventricular remodelling. Thus, NOS1 and NOS3 mediate independent, and in some cases opposite, effects on cardiac structure and function.     

Up-regulation of endothelial nitric oxide synthase by cytochrome P450 arachidonic acid epoxygenase BM3F87V

Cytochrome P450 (CYP)-dependent metabolites of arachidonic acid, epoxyeicosatrienoic acids (EETs), have been suggested to be an endothelium-derived hyperpolarizing factor (EDHF). However, the interaction or relation between EDHF and endothelial nitric oxide synthase (eNOS) is still to be elucidated. In the present study, the regulation of eNOS by endogenous EDHF is examined. The cytochrome P450 epoxygenase BM3F87V is cloned into the mammalian expression vector pCB6. Cultured bovine aortic endothelial cells (BAECs) less than 4 passages are used and transfected with BM3F87V. The effects of endogenous EETs result from BM3F87V transfection on eNOS are assessed in the endothelial cells by Western blot and Northern blot, and eNOS activity is also measured by the conversion of L-arginine to L-citrulline. Compared to transfection with the empty pCB6 vector, transfection of BAECs with BM3F87V significantly elevates the levels of eNOS protein expression, which is markedly inhibited by treatment with CYP inhibitor 17-ODYA. BM3F87V transfection also elevates the eNOS mRNA level and increases the eNOS activity. This study suggests that EDHF up-regulates eNOS gene expression.     

Localization of NOS-like protein in guard cells of Vicia faba L. and its possible function

Using the immuno-fluorescence and immuno-gold electron microscope technology, localization of ni- tric oxide synthase (NOS)-like proteins was determined in guard cells of Vicia faba L. NOS is mainly localized in nucleus, cytoplasm, chloroplast, mitochondria and the cell wall of guard cells. Scorch and exogenous JA can enhance the level of nitric oxide (NO) and increase NOS activity in both leaf and epidermis, and the changing pattern of NOS activity was consistent with the change of NO. NOS in- hibitor, L-NAME, inhibited JA-induced NO generation. From the results, we presumed that NO genera- tion from NOS pathway is the main pathway in the stress and JA responses. The pharmacological ex- periment showed that increasing the Ca2 at a suitable concentration promoted leaf NOS activity and the NO level, indicating that NOS activity together with the distribution of NO is Ca2 -dependent. NOS and NO are possibly involved in the regulation of stomatal movement thus playing an important role in plant stress responses.     

P38α对人血管内皮一氧化氮合酶(eNOS)基因启动子转录活性的影响

目的:研究P38α对人血管内皮细胞一氧化氮合酶(eNOS)基因启动子转录活性的影响.方法:利用硝酸还原酶法检测不同浓度氯化钴作用下人脐静脉血管内皮细胞-12(HUVEC-12)上清中的一氧化氮(NO)的含量.以pRL-TK为内参照,将已经构建好的pGL2-eNOS-p质粒分别与pGL3-BASIC、pcDNA3、p38a、及p38a(AF)共转染HUVEC-12细胞,利用双荧光素酶报告基因技术检测eNOS基因启动子转录活性,并在共转染的基础上加氯化钴刺激,并检测eNOS基因启动子转录活性.结果:氯化钴刺激下HUVEC-12细胞培养上清的NO含量随氯化钴作用浓度增加而提高,成功建立化学缺氧模型;p38a在正常和缺氧条件下均明显降低eNOS基因启动子的活性,可被无活性诱变体p38a(AF)逆转.结论:P38et下调人血eNOS基因启动子转录活性.     

运动训练对女子篮球运动员血清 NO、NOS活性影响的研究

通过观察6周运动训练中女大学生运动员血清NO水平、NOS活性的变化,了解篮球训练对女子运动员血清NO含量和NOS活性的影响,结果表明:实验组血清NO含量、NOS活性明显高于对照组,运动训练能够提高运动员血清NOS活性,增加NO的合成,有利于提高运动技能和保护心血管内皮的功能。     

Sarcolemma-localized nNOS is required to maintain activity after mild exercise

Many neuromuscular conditions are characterized by an exaggerated exercise-induced fatigue response that is disproportionate to activity level. This fatigue is not necessarily correlated with greater central or peripheral fatigue in patients, and some patients experience severe fatigue without any demonstrable somatic disease. Except in myopathies that are due to specific metabolic defects, the mechanism underlying this type of fatigue remains unknown. With no treatment available, this form of inactivity is a major determinant of disability. Here we show, using mouse models, that this exaggerated fatigue response is distinct from a loss in specific force production by muscle, and that sarcolemma-localized signalling by neuronal nitric oxide synthase (nNOS) in skeletal muscle is required to maintain activity after mild exercise. We show that nNOS-null mice do not have muscle pathology and have no loss of muscle-specific force after exercise but do display this exaggerated fatigue response to mild exercise. In mouse models of nNOS mislocalization from the sarcolemma, prolonged inactivity was only relieved by pharmacologically enhancing the cGMP signal that results from muscle nNOS activation during the nitric oxide signalling response to mild exercise. Our findings suggest that the mechanism underlying the exaggerated fatigue response to mild exercise is a lack of contraction-induced signalling from sarcolemma-localized nNOS, which decreases cGMP-mediated vasomodulation in the vessels that supply active muscle after mild exercise. Sarcolemmal nNOS staining was decreased in patient biopsies from a large number of distinct myopathies, suggesting a common mechanism of fatigue. Our results suggest that patients with an exaggerated fatigue response to mild exercise would show clinical improvement in response to treatment strategies aimed at improving exercise-induced signalling.     

同型半胱氨酸对钙离子激活状态下内皮细胞eNOS活性及NO含量的影响

研究同型半胱氨酸(HCY)在钙离子导体(A23187)刺激下,对内皮细胞内皮型一氧化氮合酶(eNOS)活性及一氧化氮(NO)含量的影响及机制。收集人脐静脉内皮细胞(HUVEC)进行细胞培养,取第二代细胞分4组:对照组,HCY组,A23187组和HCY A23187组。继续培养24h后,测定细胞培养液中NO、丙二醛(MDA)含量和eNOS、超氧化物歧化酶(SOD)活性。结果显示:1)与对照组相比,HCY组培养液中NO含量降低、eNOS活性减弱、MDA含量升高、SOD活力增强(P<0.05);A23187组NO含量升高、eNOS活性增强、MDA含量降低、SOD活力增强(P<0.05)。2)与A23187组相比,HCY A23187组NO含量降低、eNOS活性减弱、MDA含量升高(P<0.05),HCY不影响A23187激活状态下SOD活力的升高(P>0.05)。结论:HCY在静息及钙离子导体(A23187)激活状态下,使HUVEC中NO含量降低e、NOS活性减弱、MDA含量升高,SOD活力代偿性升高。其机制可能与HCY导致的氧化应激抑制eNOS活性及降低NO的生物利用度有关。     

NOS3多态性与高血压继发左心室肥厚的关系

目的:探讨内皮型一氧化氮合酶基因(NOS3)的第4内含子串联重复序列多态性(eNOS4a/b)与原发性高血压患者左心室肥厚的关系.方法:采取病例对照研究,应用PCR技术对高血压患者(2179人,包括1061名左心室肥厚和1118名左心室非肥厚患者)及正常对照人群(812人)进行基因分型,并经测序验证;用a表示含有4个串联重复序列的基因型,用b表示含有5个串联重复序列的基因型.测量所有病例的超声参数.结果:NOS3的eNOS4a/b基因型频率符合Hardy-Weinberg平衡;a/a、a/b、b/b基因型频率在高血压肥厚、非肥厚患者及正常人群中分布分别为0.7%、12.5%、86.8%;0.5%、10.9%、88.6%和0.6%、12.8%、86.6%.a等位基因频率分别为6.9%、6.0%和7.0%,b等位基因频率分别为93.1%、94.0%和93.1%.各基因型频率与等位基因频率在三组之间无统计学差异(P>0.05).携带不同基因型的患者的临床指标和超声参数均无差异(P>0.05).结论:本研究认为NOS3的eNOS4a/b并不增加高血压继发左心室肥厚的易感性.     

Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation.

Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) is a fundamental determinant of cardiovascular homesotasis: it regulates systemic blood pressure, vascular remodelling and angiogenesis. Physiologically, the most important stimulus for the continuous formation of NO is the viscous drag (shear stress) generated by the streaming blood on the endothelial layer. Although shear-stress-mediated phosphorylation of eNOS is thought to regulate enzyme activity, the mechanism of activation of eNOS is not yet known. Here we demonstrate that the serine/threonine protein kinase Akt/PKB mediates the activation of eNOS, leading to increased NO production. Inhibition of the phosphatidylinositol-3-OH kinase/Akt pathway or mutation of the Akt site on eNOS protein (at serine 1177) attenuates the serine phosphorylation and prevents the activation of eNOS. Mimicking the phosphorylation of Ser 1177 directly enhances enzyme activity and alters the sensitivity of the enzyme to Ca2+, rendering its activity maximal at sub-physiological concentrations of Ca2+. Thus, phosphorylation of eNOS by Akt represents a novel Ca2+-independent regulatory mechanism for activation of eNOS.     

海洛因依赖者血清一氧化氮合酶的检测及研究

目的 :了解武汉地区海洛因依赖者 NOS活性情况 ,探讨 NOS、NO与药物依赖的关系。方法 :采用最新 NOS测定试剂盒 ,以分光光度法于自动生化分析仪检测。结果 :海洛因依赖者血清 NOS活性有着显著性升高 (P〈0 .0 1) ,并与滥用时间呈正相关。结论 :NO、NOS在药物依赖机制中发挥着重要作用     

下丘脑室旁核NOS／NO系统对心血管活动的调节（综述）

下丘脑室旁核（PVN）是重要的心血管活动调节中枢。PVN分布有一氧化氮（NOS）神经元,合成并释放一氧化氮（NO）。NO通过抑制各级交感神经中枢,以及影响神经内分泌活动,对心血管活动进行调节。