雌性动物生殖系统中的一氧化氮

一氧化氮(nitric oxide,NO)属于无机自由基气体,作为一种特殊的生物传递信号分子,日益受到生命科学各领域的普遍重视。机体内的NO是由三种一氧化氮合酶(nitric oxide synthase,NOS)合成的。NOS在体内的分布极为广泛,几乎遍布机体的每一个系统。研究表明,生殖系统中的NO参与了卵泡的发育和成熟、胚胎的植入、妊娠的维持、分娩等许多生理过程。现就NO在雌性生殖系统中的作用进行阐述。     

神经型一氧化氮合酶的活性调控

一氧化氮是重要的信使分子,在生物体内参与众多生理及病理过程。生物体内存在着复杂的一氧化氮合酶活性调控机制以精确调控一氧化氮的生成。在神经系统中,一氧化氮主要由神经型一氧化氮合酶催化生成。神经型一氧化氮合酶的活性主要受到翻译后水平上钙离子和钙调蛋白的调控,其调控方式包括二聚化、多位点的磷酸化和去磷酸化,以及主要由PDZ结构域介导的蛋白质-蛋白质相互作用。一氧化氮本身对其合酶的活性具有负反馈调控作用。近年来的研究提示,细胞质膜上的脂筏微区在神经性一氧化氮合酶的活性调控中也起到重要的调节作用。     

植物体内一氧化氮合成途径研究进展

一氧化氮(NO)作为一种气体信号分子,在植物生理过程中发挥重要作用,它参与调节植物的生长、发育及对外界环境的应激反应.植物体内主要通过酶催化途径和非酶催化途径合成NO.酶催化途径合成NO的主要酶包括一氧化氮合酶(nitric oxide synthase,NOS)和硝酸还原酶(nitrate reductase,NR),以及在某些植物的特定组织或器官或在特殊环境条件下存在的一氧化氮氧化还原酶(nitric oxide oxidoreductase,Ni-NOR)和黄嘌呤氧化还原酶(xanthine oxidoreductase,XOR).非酶催化合成途径主要是在酸性和还原剂存在条件下将亚硝酸盐还原成NO.该文主要结合研究方法,综述了植物体内NO合成途径的研究进展,为植物体内NO信号的作用机理的深入研究提供信息资料.     

大鼠脑组织中一氧化氮合酶测定

在含有一氧化氮合酶(NOS)底物左族精氨酸(L-Arg), 辅助因子还原性辅酶Ⅱ(NADPH)、四氢生物蝶呤(BH₄)、黄素单核苷酸(FMN), 黄素腺嘌呤二核苷酸(FAD)以及Ca²⁺、钙调蛋白等溶液中加入大鼠脑组织匀浆离心上清液, 组成酶反应体系. 37℃温育80min, 应用N-(1-萘基)-乙二胺、对氨基苯磺酸的重氮、偶氮反应测定酶反应体系中一定时间内NO代谢产物NO^-₂浓度变化, 建立一种简便的NOS活性测定方法. 反应体系最佳pH为7.4, K_m=0.1mmol/L, 体系内NO^-₂生成量与加入样品量之间有良好线性关系(r=0.998). 此方法简单、方便、重复性好, 批内CV为3.69%, 批间CV为5.16%. 10只健康大鼠脑组织中NOS活性为(39.61±7.64)nmol/(min·g).     

软体动物的一氧化氮及其合酶的研究进展

一氧化氮作为一种重要的信息分子,参与调节软体动物的嗅觉、运动、取食、机体防御及学习行为。本文从生理、生化、形态定位以及信号转导几方面综述了有关软体动物一氧化氮及其合酶的最新研究进展。     

Cyclosporin-A Inhibits Constitutive Nitric Oxide Synthase Activity and Neuronal and Endothelial Nitric Oxide Synthase Expressions after Spinal Cord Injury in Rats

Nitric oxide (NO) plays a role in the pathophysiology of spinal cord injury (SCI). NO is produced by three types of nitric oxide synthase (NOS) enzymes: The constitutive Ca²⁺/calmodulin-dependent neuronal NOS (nNOS) and endothelial NOS (eNOS) isoforms, and the inducible calcium-independent isoform (iNOS). During the early stages of SCI, nNOS and eNOS produce significant amounts of NO, therefore, the regulation of their activity and expression may participate in the damage after SCI. In the present study, we used Cyclosporin-A (CsA) to further substantiate the role of Ca-dependent NOS in neural responses associated to SCI. Female Wistar rats were subjected to SCI by contusion, and killed 4 h after lesion. Results showed an increase in the activity of constitutive NOS (cNOS) after lesion, inhibited by CsA (2.5 mg/kg i.p.). Western blot assays showed an increased expression of both nNOS and eNOS after trauma, also antagonized by CsA administration.     

Down-Regulation of Neuronal Nitric Oxide Synthase by Nitric Oxide After Oxygen-Glucose Deprivation in Rat Forebrain Slices

Abstract : The precise role that nitric oxide (NO) plays in the mechanisms of ischemic brain damage remains to be established. The expression of the inducible isoform (iNOS) of NO synthase (NOS) has been demonstrated not only in blood and glial cells using in vivo models of brain ischemia-reperfusion but also in neurons in rat forebrain slices exposed to oxygen-glucose deprivation (OGD). We have used this experimental model to study the effect of OGD on the neuronal isoform of NOS (nNOS) and iNOS. In OGD-exposed rat forebrain slices, a decrease in the calcium-dependent NOS activity was found 180 min after the OGD period, which was parallel to the increase during this period in calcium-independent NOS activity. Both dexamethasone and cycloheximide, which completely inhibited the induction of the calcium-independent NOS activity, caused a 40-70% recovery in calcium-dependent NOS activity when compared with slices collected immediately after OGD. The NO scavenger oxyhemoglobin produced complete recovery of calcium-dependent NOS activity, suggesting that NO formed after OGD is responsible for this down-regulation. Consistently, exposure to the NO donor ( Z )-1-[(2-aminoethyl)- N -(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate) for 180 min caused a decrease in the calcium-dependent NOS activity present in control rat forebrain slices. Furthermore, OGD and DETA-NONOate caused a decrease in level of both nNOS mRNA and protein. In summary, our results indicate that iNOS expression down-regulates nNOS activity in rat brain slices exposed to OGD. These studies suggest important and complex interactions between NOS isoforms, the elucidation of which may provide further insights into the physiological and pathophysiological events that occur during and after cerebral ischemia.     

糖皮质激素对机械通气大鼠肺组织iNOS、NO表达的影响

目的通过观察糖皮质激素对机械通气大鼠肺组织诱导型一氧化氮合酶（iNOS）及一氧化氮（NO）表达的影响,探讨糖皮质激素对呼吸机所致肺损伤（ventilator induced lung injury,VILI）的干预作用。方法 24只雄性Wistar大鼠随机分为对照组、机械通气组、地塞米松（DXM）干预组。用逆转录-聚合酶链反应（RT-PCR）法检测肺组织iNOS mRNA表达,用免疫组织化学染色法检测肺组织iNOS蛋白表达,用硝酸还原酶法测定肺组织和血浆NO含量。结果机械通气组和DXM干预组大鼠肺组织iNOS mRNA及其蛋白表达水平,以及血浆和肺组织NO含量均明显高于对照组（P〈0.01）;DXM干预组上述指标与机械通气组比较均明显降低（P〈0.01）。结论糖皮质激素可通过抑制肺组织iNOS的表达,减少NO的生成,对机械通气大鼠肺组织具有保护作用。     

一氧化氮合酶的若干研究进展

一氧化氮合酶(NOS)是一氧化氮(NO)生物学与医学研究的重要内容.近年来,对NOS酶本质及其生化与分子生物学特性甚至某些分子遗传学方面的认识都在迅速发展和深化.研究表明,干预NOS-NO途径的某些环节,如酶激活、NO合成、释放与转运甚至有关酶的编码基因及其表达,将为某些临床问题的解决提供新的思路和手段．     

神经系统中的一氧化氮

一氧化氮(NO)是一种广泛存在的独特的生物信使因子和效应因子.NO参与脑内许多生理功能和病理生理过程.NO调节神经递质释放和脑血流,参与神经发育和基因表达调控.NO可能作为一种逆行信使物质参与海马的长时程突触传递增强和小脑的长时程突触传递抑制.过多的NO则具有神经毒性并与许多神经系统疾病有关.     

一氧化氮与雄性生殖系统

一氧化氮是近年来发现的一种重要的生物信号分子和效应分子 ,在生物体内 ,L 精氨酸在一氧化氮合酶的作用下生成一氧化氮后 ,以自分泌或旁分泌形式作用于自身或邻近的细胞 ,发挥信号传导和细胞毒性等多种生理功能。近年来的研究表明 ,一氧化氮对雄性生殖系统上至下丘脑 ,下到性腺、附性器官都具有十分重要的生理调节作用。     

Nitric Oxide Cycle in Mammals and the Cyclicity Principle

This paper continues a series of reports considering nitric oxide (NO) and its cyclic conversions in mammals. Numerous facts are summarized with the goal of developing a general concept that would allow the statement of the multiple effects of NO on various systems of living organisms in the form of a short and comprehensive law. The current state of biological aspects of NO research is analyzed in term of elucidation of possible role of these studies in the system of biological sciences. The general concept is based on a notion on cyclic conversions of NO and its metabolites. NO cycles in living organisms and nitrogen turnover in the biosphere and also the Bethe nitrogen–carbon cycle in star matter are considered. A hypothesis that the cyclic organization of processes in living organisms and the biosphere reflects the evolution of life is proposed: the development of physiological functions and metabolism are suggested to be closely related to space and evolution of the Earth as a planet of the Solar System.     

New Donors and Acceptors of Nitrogen Oxide as Potential Therapeutic Agents

The synthesis of new donors and acceptors of nitrogen oxide is described. New lipophilic nitronylnitroxyl radicals (NNR) that act as paramagnetic scavengers of nitrogen oxide are synthesized and characterized. The purity of the preparations is determined, and their structures are confirmed. The lipophilicity of the radicals is tested by ESR spectroscopy. The incorporation into lipid multilayers is shown to protect NNR from reduction in biological samples, while their ability to scavenge nitrogen oxide and form iminonitroxyl radicals is retained. A decreased rate of NNR reduction under these conditions substantially enhances their effectiveness as paramagnetic acceptors of nitrogen oxide in biological systems. The synthesis of a new hydrophilic NO donor, 3-bromo-3,4-dihydro-4,4-dimethyl-3-(2-pyridyl)-diazet-1,2-dioxide (DD_pyr), is described. The constants of DD_pyr decomposition in tris-HCl buffer (pH 7.5) and in DMSO are determined (4.5 × 10^–6 and 0.5 × 10^–6 s^–1, respectively). A substantially higher rate of DD_pyr decomposition in buffer, compared with the decomposition rates determined previously for some diazetines, makes DD_pyr a prospective candidate for the use in aqueous media. It is found in experiments on perfused rat caudal artery that DD_pyr is an effective vasodilator. Intraperitoneal injection of DD_pyr to hereditarily hypertensive rats (ISIAH line) at doses of 100–200 g/kg body mass considerably diminishes their systolic arterial pressure.     

植物一氧化氮生物学的研究进展

一氧化氮(NO)是植物中的一种关键的信号分子.在植物中,NO的潜在来源包括一氧化氮合成酶、硝酸还原酶、黄嘌呤氧化还原酶和非酶促途径.NO能促进植物生长,延缓叶片、花和果实衰老,促进休眠和需光种子的萌发,能与植物激素相互作用调节气孔运动,诱导程序性细胞死亡和防御相关基因的表达,并在逆境中作为一种抗氧化剂起作用.NO的细胞内信号反应包括环鸟苷酸、环腺苷二磷酸核糖的产生和细胞质Ca2 浓度的增加,其信号转导途径及其生物化学和细胞学本质还不十分清楚.     

手性苯基环氧乙烷的生物不对称合成

以苯乙烯为唯一碳源和能源,从不同来源的土壤样品中初筛分离出12株好氧细菌和2株真菌,经复筛,对液体培养物进行手性气相色谱分析,得到一株产生手性苯基环氧乙烷活力较高的菌种PS-1206,并对其发酵、产酶及苯乙烯的全细胞转化进行了研究,利用微生物细胞在30℃,pH 7.0,10mmol/L磷酸缓冲液中转化0.5%苯乙烯10h,获得?苯基环氧乙烷,e.e%值为80%,转化产率为35%。     

一氧化氮在植物中的生理功能

一氧化氮是植物体内一种重要的活性分子,它对植物的种子萌发、生长发育、气孔运动、呼吸作用以及抗逆反应等生理过程起重要的调节作用,与植物激素存在密切关系。现对一氧化氮在植物中的生理功能进行综述。     

一氧化氮在心肌缺血再灌注损伤中的调节作用 及相关治疗药物研究进展

一氧化氮 ( NO ) 是体内调节心血管系统功能的重要信号分子,在血管收舒、血小板活性调节、细胞增殖凋亡、氧化应激及炎症反 应等过程中发挥了不可或缺的作用。在心肌缺血再灌注过程中,随着一氧化氮合成酶表达和 NO 底物水平的动态变化,NO 生成的时间和 产量均会发生变化,导致其作用具有两面性。综述 NO 的产生与作用、在心肌缺血再灌注损伤中的作用和影响因素以及相关治疗药物及作 用机制的研究进展,为心肌缺血再灌注损伤的有效治疗和进一步研究提供参考     

Nitric Oxide in Arthritis

Nitric oxide’s (NO) involvement in arthritis was first demonstrated when levels of nitrite, a stable endproduct of NO metabolism, were shown to be elevated in serum and synovial fluid samples of rheumatoid and osteoarthritis patients. NO production by chondrocytes, its involvement in various biochemical events of cartilage metabolism, and the in vivo suppression of experimental arthritis by NO synthase inhibitors further implicated NO in arthritis. However, a conclusive role for NO in the pathogenesis of arthritis remains to be defined, in contrast to the NO-cGMP signal transduction pathway of endothelium-mediated vasodilation. It appears that NO has limited modulating effects in cartilage metabolism, with evidence for both protective and deleterious effects. Recent developments that contribute to our understanding of NO’s role in arthritis are discussed.