动物中活性氧的产生及清除机制

各种氧化应激使动物细胞中积累大量的活性氧,从而导致畜禽生产性能的下降.动物体内有效清除活性氧的保护机制分为酶促和非酶促两类.酶促系统包括超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化物酶(POD).非酶促系统包括抗坏血酸(Vc)、谷胱甘肽、维生素E、类胡萝卜素等.在动物日粮中添加抗氧化剂来维持抗氧化平衡,是集约化管理条件下维持畜禽良好生产性能和繁殖性能的一个重要方法.     

畜禽硒和维生素E缺乏症的临床症状、剖检变化与防治

硒是动物体内谷胱甘肽过氧化物酶的组成部分,能够分解动物体内由于生物氧化产生的剧毒过氧化物,保护细胞及亚细胞结构的脂质膜免受破坏,同时又是体内多种蛋白质的组成成分,对动物机体抗氧化、抗应激、提高免疫力等方面起着重要作用。补硒能防治动物肝脏疾病,保障机体健康,提高畜禽产品质量。当动物体内缺硒或供给不足时,谷胱甘肽过氧化物酶的活性降低,导致过氧化物分解,在体内起毒害作用,引起细胞变性、坏死,出现一系列临床症状和病理变化。维生素E影响动物的生殖功能,可使垂体前叶促性腺分泌细胞兴奋、分泌增加,维持生殖系统的正常功能。     

硒和硒蛋白调节动物抗氧化功能及硒在畜牧生产中应用的研究进展

谷胱甘肽过氧化物酶1(Glutathione Peroxidase1,GPX1)、硫氧还蛋白还原酶(Thioredoxin Reductase,TrxR)/硫氧还蛋白(Thioredoxin,Trx)是在机体中发挥抗氧化功能的硒蛋白。GPX1可提高动物抗氧化能力,抑制核因子кB(Nuclear Factor Kappa B,NF-кB)信号通路,减缓细胞氧化损伤,激活核因子E2相关因子2/抗氧化反应元件通路,提高Trx和TrxR蛋白活性,增强Trx/TrxR系统抗氧化功能,降低促炎因子和活性氧等产生,维持机体氧化还原稳态。因此,本文着重阐述GPX1、Trx与TrxR对动物抗氧化系统的调控作用及硒在畜牧生产中的应用进展,为硒及硒蛋白增强动物抗氧化功能方面的研究及硒在畜牧生产中的应用提供理论参考。     

硒的营养与生理作用研究进展

硒是动物机体必需的微量元素,在生物体内参与重要的生理活动,它是谷胱甘肽过氧化物酶的重要组成成分,能消除机体内产生的自由基,保护胰脏,从而维持胰脏正常功能,促进消化酶分泌,促进畜禽生长.硒参与机体蛋白质、脂肪和碳水化合物代谢,参与调节酶促反应和氧化还原过程.     

GPX2对肠道炎症通路的作用机制及营养调控的研究进展

谷胱甘肽过氧化物酶2(Glutathione Peroxidase 2,GPX2)主要聚集于胃肠道组织,以其抗氧化作用保护上皮组织免受过氧化氢、自由基、肿瘤坏死因子等有害物质侵害。GPX2抑制核因子-кB和活性氧介导的肠道炎性通路激活,进而减轻下游炎症物质损伤肠道。本文重点阐述GPX2对动物炎症通路的调控作用及其在动物生产方面的营养调控作用,旨在为维护肠道稳态、预防畜禽肠炎发生提供参考。     

日粮硒对雏鸡肝脏、胰腺谷胱甘肽过氧化物酶活力影响的试验

谷胱甘肽过氧化物酶可分为依硒型(Se—GsH—Px)和非依硒型(NonSe—GSH—Px)。Tappel证实,非依硒型谷胱甘肽过氧化物酶就是谷胱甘肽硫转移酶,并指出在评定硒营养时,仅测定依硒型谷胱甘肽过氧化物酶是不充分的,测定非依硒型谷胱甘肽过氧化物酶的活力,有助于揭示动物种属不同对硒反应性疾病发生与否的物质基础,也有助于进一步阐明硒缺乏症的发病机理。为此,本试验采用异丙基过氧化氢法,探讨日粮硒对雏鸡肝脏、胰腺含硒量及依硒型和非依硒型谷胱甘肽过氧化物酶活力的影响。     

硒的生物学特性及机制研究

1硒的生物学功能 1.1硒的抗氧化作用 硒对畜禽机体的抗氧化作用主要通过谷胱甘肽过氧化物酶(GPx)酶促反应清除脂质过氧化物,因此,通常将GPx活性作为衡量硒在生物体内的功能指标.     

硒在家禽生产中的应用效果

硒作为动物体内的营养元素 ,近年来已广泛应用于畜禽的饲料中。国内外大量研究资料表明 ,硒在动物体内的新陈代谢中 ,起着极为重要的作用。当机体内硒缺乏或不足时 ,畜禽生产性能将会下降 ,甚至出现病变。如白肌病、桑椹白肌病、繁殖功能下降、脑软化症。1　硒的生物学功能1 1　硒是一些酶的组成成分　硒是谷胱甘肽过氧化物酶 (ＧＳＨ-Ｐｘ)的主要成分。该酶分解过氧化氢 ,维持细胞膜结构完整与正常的功能。当机体摄入量达到要求时可保护心脏、肝脏 ,延缓衰老。另外硒参与辅酶Ｑ的合成 ,促进丙酮酸脱羧 ,因而在三羧酸循环及呼吸链电子传递…     

硒对动物免疫功能的影响

硒是机体不能缺少的一种微量元素。硒的生物学功能是多方面的,其中最重要的是它的抗氧化功能,特别是作为谷胱甘肽过氧化物酶(GSH-Px)重要组分,在对抗体内有氧代谢过程中所产生过氧化氢对细胞的破坏作用时必不可少。谷胱甘肽过氧化物酶(GSH-Px)是抗过氧化物的重要酶,其主要功能是阻止过氧化物和自由基的形成。硒正是通过抗过氧化物和清除自由基,减少或延迟脂褐素的形成,从而达到抗细胞衰老和死亡的目的。同样,硒对增强动物的免疫功能也起着十分重要的作用。本文就硒对非特异性免疫、细胞免疫及体液免疫的影响及其硒影响免疫的机制进行综…     

自拟药方"祛衣灵"对小鼠抗氧化腹胀的研究

在正常情况下,动物体内有一套完整的清除体内自由基的体系,包括谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD).GSH-Px是生物机体抗氧化系统中重要的抗氧化分子,在抵抗氧自由基损伤、维持细胞蛋白质结构与功能和机体氧化还原平衡等方面发挥着重要的作用.SOD是动物机体内重要的抗氧化酶类,其作用是清除自由基和过...     

Oxidative stress and bovine liver diseases: role of glutathione peroxidase and glucose 6-phosphate dehydrogenase

This article summarizes the different types of free radicals, antioxidants and the effect of oxidative stress on the activities of glutathione peroxidase and glucose 6-phosphate dehydrogenase in bovine liver diseases. A growing body of evidence suggests that the formation of reactive oxygen species is a common occurrence associated with most if not all disease processes. The overall importance of reactive oxygen species to the progression and severity of various disease states varies greatly depending on the conditions and whether the disease is acute or chronic. Free radical researches in animals are in progress and further investigations are needed to establish the involvement of reactive oxygen species in diseases affecting different animal species and the pathology they produce.     

Role of antioxidants in the protection against oxidative stress in cattle--trace elements and enzymatic mechanisms (Part 3)

The most important enzymatic mechanisms which protect an organism against oxidative stress are superoxide dismutase (SOD), peroxidase (Px), e.g. glutathione peroxidase (GSH-Px) and ascorbate peroxidase, catalase and glutathione reductase. Their activity depends on many trace elements. Enzymatic mechanisms, functioning under physiological conditions, prevent the spread of free radical reactions. New and reoccurring metabolic and infectious diseases of cattle emerge when there is a disproportion in the balance between reactive oxygen species and antioxidative enzymatic barrier.     

Antioxidant systems and lymphocyte proliferation in the horse,sheep and dog

To better define the species-specific antioxidant systems and to ascertain the influence of the intracellular redox status on the immune system of different animal species, we determined lymphocyte glutathione peroxidase (GSHPx) activity, plasmatic glutathione levels (GSH) and the effect of H2O2 on the responsiveness of lymphocytes to proliferative stimuli. Among the three species considered, sheep presented the lowest plasmatic GSH and the highest lymphocyte GSHPx activity. On the contrary, dogs showed an inverted pattern (high GSH - low GSHPx). Horses displayed intermediate values for both parameters analysed. The effect of H2O2 on the proliferative capacity of lymphocytes was the same for all three species; the 200 microM dose in particular was strongly inhibiting. Each species, however, showed different rates of inhibition: sheep exhibited the highest sensitivity to the antiproliferative effect of H2O2. Our results confirmed that high H2O2 concentrations (200 microM) are noxious for the cellular functions of all animals; however this effect is mediated by a rigorously species-specific relationship between the intracellular reactive oxygen species (ROS) and the molecular systems involved in cell proliferation.     

Dietary incorporation of feedstuffs naturally high in organic selenium for racing pigeons (Columba livia): effects on plasma antioxidant markers after a standardised simulation of a flying effort

Selenium is a trace element of importance for animal health. It is essential for adequate functioning of many enzymes such as, the antioxidant enzyme, glutathione peroxidase, which protects the cell against free radicals. A muscular effort induces a rise in reactive oxygen species production which, in turn, can generate an oxidative stress. Two groups of eight racing pigeons were fed respectively with a diet containing 30.3 (control group) and 195.3 (selenium group) μg selenium/kg diet. The pigeons were submitted to a standardised simulation of a flying effort during 2 h. Blood was taken before and after the effort to measure antioxidant markers and blood parameters related to muscle metabolism. Plasma selenium concentration and glutathione peroxidase activity were significantly higher in the selenium group. There were no significant differences for the other measured parameters. As a consequence of the effort, the pigeons of the selenium group showed a higher increase of glutathione peroxidase activity and a smaller increase of plasma lactate concentration. Variations because of the effort in the other markers were not significantly different between the two groups. It is concluded that the selenium status was improved with the feeding of feedstuffs high in Selenium.     

Altered Oxidant–Antioxidant Profile in Canine Mammary Tumours

Mammary tumours are the most common neoplasms in female dogs. Oxidative stress arising due to overproduction of reactive oxygen species, coupled with altered antioxidant capacities has been implicated in the pathogenesis of all types of cancers. However, the extent of lipid peroxidation and the status of antioxidants in canine mammary tumours have not been investigated. The present study was designed to evaluate the oxidant-antioxidant profile in canine mammary tumours. Lipid peroxidation as evidenced by the formation of thiobarbituric acid-reactive substances, lipid hydroperoxides, and conjugated dienes, as well as the status of the antioxidants superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase, glutathione S-transferase and vitamin C, in tumour tissues of 25 bitches was estimated. Lipid peroxidation in tumour tissues was enhanced compared to the corresponding adjacent uninvolved tissues. This was accompanied by significant elevation in both enzymatic and non-enzymatic antioxidants. This study suggests that upregulation of antioxidants induced by lipid peroxidation confers a selective growth advantage to tumour cells over their adjacent normal counterparts.     

褪黑素对低温和干旱胁迫下多年生黑麦草幼苗生长和抗氧化系统的调节作用

本研究以‘顶峰Ⅲ’为供试多年生黑麦草（Lolium perenne）品种,研究了低温和干旱胁迫下内源褪黑素（melatonin,MT）的响应,并采用叶面喷施不同浓度MT （0,20,100,1 000 μM）的方法,探讨了MT对低温和干旱胁迫下黑麦草幼苗生长和抗氧化防御系统的影响。结果表明：低温和干旱胁迫下内源MT水平均显著增加（P<0.05）;在不同胁迫强度下,喷施一定浓度的MT会在一定程度上降低叶片相对电导率、使幼苗鲜重发生改变,其中100 μM的MT处理对提高幼苗鲜重和降低相对电导率的效果最佳;低温和干旱胁迫下,黑麦草叶片中O₂^·-,H₂O₂和丙二醛（malondialdehyde,MDA）含量显著增加;过氧化物酶（peroxidase,POD）,过氧化氢酶（catalase,CAT）,抗坏血酸过氧化物酶（ascorbate peroxidase,APX）和谷胱甘肽还原酶（glutathione reductase,GR）活性发生不同程度的改变;MT显著地降低了MDA和活性氧的积累,提高了CAT,APX和GR活性及脯氨酸含量。综上,低温和干旱胁迫下MT能够诱导植物体内抗氧化酶活性增强和脯氨酸积累,有效地清除活性氧,从而缓解了黑麦草的生长抑制,增强了其抗寒和抗旱性。     

GSH对铅胁迫下多年生黑麦草幼苗抗氧化系统的调控

本试验以12周龄的多年生黑麦草（Lolium perenne ‘cuttle’）幼苗为试验材料,用铅（Lead,Pb）,Pb+还原型谷胱甘肽（Glutathione,GSH）和Pb+丁硫氨酸-亚砜亚胺（L-Buthionine-sulfoximine,BSO）处理1周,研究GSH对Pb胁迫下多年生黑麦草抗氧化系统的调控机理,寻求缓解植物Pb胁迫的有效措施。结果表明：Pb胁迫下,外源GSH能够显著提高多年生黑麦草Pb的吸收和转运,增加抗氧化酶超氧化物歧化酶（Superoxide dismutase,SOD）、谷胱甘肽过氧化物酶（Glutathione peroxidase,GPX）和谷胱甘肽还原酶（Glutathione reductase,GR）活性,显著增加抗氧化剂GSH含量及GSH/氧化型谷胱甘肽（Oxidized glutathione,GSSG）比率,提高了植物的还原力。外源GSH也能够显著降低活性氧超氧阴离子（Superoxide anion,O₂^·-）和过氧化氢（Hydrogen peroxide,H₂O₂）的产生量、膜的相对透性（Relative electric conductivity,EC）和丙二醛（Malondialdehyde,MDA）含量,保持了细胞的稳定性,减轻了膜脂的过氧化程度。外源BSO作用基本上与GSH相反。相关分析表明：GSH可通过提高SOD和GPX等抗氧化酶的活性,促进GSSG和GSH的相互转化,降低活性氧产生量,提高植物抵抗逆境胁迫的能力。     

土壤重金属镉胁迫对石竹幼苗生长的影响及其机理

为了揭示土壤重金属镉(Cd)对植物的毒害机理,采用温室盆栽试验方法,研究了不同浓度(0, 0.3, 1, 3, 10, 30和50 mg/kg)Cd污染土壤对石竹幼苗生长以及对抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响。结果表明,石竹幼苗的分蘖数、株高和生物量表现出显著的“低促高抑”的现象,这缘于土壤Cd低浓度(≤1 mg/kg)胁迫和胁迫的初期,石竹叶片的超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDAR)、脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)等抗氧化酶活性提高,以抵抗体内逐渐增多的活性氧(ROS);随着Cd浓度的增加和镉胁迫时间的延长,石竹叶片中的超氧阴离子(O₂^-·)和过氧化氢(H₂O₂) 等ROS爆发,SOD、APX、MDAR、DHAR和GR等抗氧化酶活性迅速降低,抗坏血酸(AsA)和谷胱甘肽(GSH)含量减少,过多的ROS不能被石竹自身的抗氧化系统有效地清除,最终导致膜脂过氧化受到逆境伤害。另外,试验结果验证了APX是清除H₂O₂的重要酶,GR是生成GSH的重要酶,MDAR还原MDHAR是AsA-GSH循环中再生AsA的主要途径。     

Effect of dietary supplementation with vitamins E and C on production performance, immune responses and antioxidant status of White Leghorn layers under tropical summer conditions

1. The effects of vitamin E (DL-alpha-tocopheryl acetate) and vitamin C (ascorbic acid) supplementation on performance, some immune variables and antioxidant status of White Leghorn layers (aged 44-56 weeks) exposed to tropical summer conditions were investigated. 2. Both vitamins E and C significantly improved the egg production, food conversion efficiency, antibody responses to inoculated sheep red blood cells (SRBC) and Newcastle disease virus (NDV) vaccine, lymphocyte proliferation in response to mitogen and activities of antioxidant enzymes red blood cell catalase (RBCC) and glutathione peroxidase (GSH-PX) in layers. Vitamin C increased the inflammatory response to phytohaemagglutinin-P (PHA-P) inoculation. 3. Supplemental vitamin C at 200 mg/kg diet significantly increased eggshell weight, eggshell thickness, and shell breaking strength. However, no effect of supplemental vitamin E on eggshell quality was observed. 4. Vitamins E and C, as well as interactions between them, significantly influenced the activities of glutathione reductase and lipid peroxidase. A combination of vitamin E at 125 IU/kg with vitamin C at 200 mg/kg diet had an additive effect on reducing the activity of oxidative enzyme lipid peroxidase (LP) and increasing the activity of antioxidant enzyme glutathione reductase (GSHR). 5. It is concluded that vitamin E (125 IU/kg) and vitamin C (200 mg/kg) could independently alleviate the effects of heat stress on production performance and immunological variables of layers. However, combination of both the vitamins at the above-mentioned concentrations is beneficial in eliciting higher antioxidant status in laying hens exposed to tropical summer conditions.     

燕麦劣变种子吸胀过程中线粒体AsA-GSH循环的生理响应

为探究种胚线粒体抗坏血酸-谷胱甘肽（ascorbate-glutathione，AsA-GSH）循环响应老化的抗氧化作用机制，本试验通过控制劣变处理获得高活力和中活力燕麦（Avena Sativa.L）种子，以未老化种子作为对照，研究了吸胀过程中的发芽特性、种胚线粒体活性氧（reactive oxygen species，ROS）含量以及AsA-GSH循环酶活性和抗氧化物质的变化规律。结果显示，随着燕麦种子活力的下降，发芽率、活力指数、发芽指数、根长、苗长下降以及平均发芽时间增加。燕麦种子劣变主要通过降低AsA-GSH循环中抗坏血酸过氧化物酶（ascorbate peroxidase，APX）、谷胱甘肽还原酶（glutathione reductase，GR）活性以及GSH/氧化型谷胱甘肽（oxidized glutathione，GSSG）比值，使种胚线粒体内ROS积累，产生氧化损伤，继而对种子萌发和幼苗生长产生不良影响。