锌对应激大鼠海马金属硫蛋白亚型表达的调控作用及机制研究

目的　观察不同锌摄入水平对应激大鼠海马脑区不同金属硫蛋白亚型表达的影响。方法　将Wistar雄性大鼠随机分为 8组 :正常对照组、对喂组、缺锌组和补锌组及其相应的应激组 ,分别给予正常饲料、缺锌饲料和补锌饲料 ,以缺锌动物当日的饲料摄入量作为对喂动物次日的给料量。动物喂饲 1周后开始束缚应激 ,持续 4周。以血红蛋白镉饱和法测定脑组织金属硫蛋白含量 ,分离海马提取总RNA ,以RT PCR检测金属硫蛋白亚型MT -1mRNA和MT -3mRNA。结果　缺锌动物出现血锌含量明显降低 ,脑组织金属硫蛋白含量和海马金属硫蛋白mRNA的表达均出现降低 ,但其表达在缺锌应激组动物仍有明显升高 ;而补锌动物金属硫蛋白的表达有所增加 ,补锌应激组动物的表达增加更加明显。缺锌和缺锌应激组动物的血浆皮质醇、IL -1、IL- 6和NO水平也较其它组显著升高。结论　缺锌可降低动物脑和海马组织中金属硫蛋白的表达 ,但缺锌动物在接受应激刺激后 ,金属硫蛋白的表达仍可明显增加 ;而补锌可增加金属硫蛋白的表达 ,补锌应激使脑组织中金属硫蛋白的表达升高更为显著 ;应激对动物的损伤作用与其锌营养状况有关 ,缺锌可降低机体对应激的抵抗能力。     

锌对心理应激大鼠不同脑区金属硫蛋白亚型表达的影响

目的:观察不同锌摄入水平对心理应激大鼠不同脑区金属硫蛋白亚型表达的影响。方法:将Wistar大鼠随机分为8组:正常对照组、对喂组、缺锌组和补锌组及其相应的应激组,分别给予正常、缺锌和补锌饲料,以缺锌动物当日的饲料摄入量作为对喂动物次日的给料量。动物喂饲1w后开始束缚应激,持续4w。分别以蛋白印迹法和RT-PCR测定海马、皮质、间脑和嗅球金属硫蛋白含量以及MT-1mRNA和MT-3mRNA的表达;并以ELISA法检测血浆IL-6和IL-1的含量。结果:缺锌动物的血锌含量明显降低,缺锌应激动物不同脑区金属硫蛋白及其亚型mRNA的表达均较缺锌动物明显升高,但其增加幅度低于其它应激组;而补锌应激动物的表达增加幅度最大。缺锌组和各应激组动物的血浆皮质醇、IL-1、IL-6水平出现显著升高。另外,金属硫蛋白在不同脑区的表达水平不同:海马>嗅球>皮质>间脑。结论:不同锌营养状况可影响心理应激动物不同脑区金属硫蛋白的表达,海马脑区表达水平较高可能与海马在应激反应中的重要作用相关联。糖皮质激素及IL-6、IL-1等细胞因子可能对金属硫蛋白的表达发挥了诱导作用。     

缺锌和补锌对烫伤大鼠血清和组织锌含量,含锌酶、激素、蛋白质的影响

目的 观察缺锌和补锌对烫伤大鼠体内锌、含锌酶、激素和蛋白质含量的影响。方法 雄性Sprague-Dawley大鼠112只，56只用含锌量正常（40μg/g）的饲料喂养，其余56只用含锌4μg/g的低锌饲料喂养，1周后各取8只大鼠，40μg/g锌喂养大鼠为正常对照组（NC组），4μg/g锌喂养的为缺锌对照组（DC组），处死后留取标本。其余大鼠15％深Ⅱ度烫伤，40μg/g锌喂养大鼠随机分为正常烫伤组（NB组，继续用含锌40μg/g饲料喂养）和烫伤补锌组（NH组，改用含锌80μg/g饲料喂养）；4μg/g锌喂养大鼠随机分成缺锌烫伤组（DB组，改用含锌10μg/g饲料喂养）和缺锌烫伤补锌组（DH组，改用含锌80μg/g的饲料喂养），各组24只大鼠。分别于烫伤后第1、3、7天，各组处死大鼠8只，留取标本检测血清、肝脏、骨骼和皮肤锌含量以及血清碱性磷酸酶（ALP）、生长激素（GH）和肝脏金属硫蛋白（MT）水平。结果 烫伤前缺锌大鼠血清、肝脏、骨骼和皮肤锌含量以及ALP、GH和肝脏MT水平均低于正常大鼠。烫伤后缺锌和正常大鼠的血清、骨骼锌含量及ALP下降，肝脏、烫伤皮肤锌、GH和肝MT呈上升趋势；补锌后血清、组织锌、ALP、GH、MT均明显上升，但缺锌大鼠的变化幅度小于正常大鼠。结论 机体缺锌不仅使血清、组织中锌含量下降，还影响含锌酶ALP、GH和肝脏MT的活性及功能。口饲补锌可以纠正缺锌状态，烫伤后应注意锌的补充。     

精神应激时锌的抗过氧化作用研究

在电击和束缚两种精神应激条件下，观察了缺锌和补锌大鼠体内过氧化反应和抗氧化系统的不同变化。结果表明缺锌动物受应激影响后体内过氧化物水平显著高于补锌组；其肝脏金属硫蛋白合成减少，而血液ＳＯＤ活性呈代偿性增强。提示在精神应激时保持良好的锌营养有利于减轻过氧化损伤。     

应激对大鼠海马金属硫蛋白亚型表达的影响

目的 :　观察应激对大鼠海马脑区金属硫蛋白亚型表达的影响。方法 :　以束缚为应激原建立心理应激动物模型。将动物随机分为四组 :正常对照组 (Ctr)、束缚 1 w组 (R1 )、束缚 2w组 (R2 )和束缚 4w组 (R4)。取动物脑和肝脏以镉饱和法测定金属硫蛋白含量 ,取海马组织提取总 RNA,以 RT- PCR检测金属硫蛋白亚型 MT- 1 m RNA和 MT- 3m RNA,并取血测定血浆皮质醇和 IL- 6水平。结果 :　束缚应激后 ,大鼠体重增长明显减慢 ,血浆皮质醇、IL- 6水平显著高于Ctr组 ;海马脑区两种亚型金属硫蛋白 m RNA的表达水平升高 ,脑和肝脏金属硫蛋白含量也明显增加。结论 :　束缚应激可影响海马金属硫蛋白的表达 ,使其在蛋白质水平和 m RNA水平均出现明显升高 ,其可能机制是 ,在应激条件下皮质醇和 IL- 6等因子的上调对这种应激蛋白的表达发挥了诱导作用     

锌或铜诱导肝脏金属硫蛋白结合锌镉比值与铜镉比值的研究

[目的]观察镉（Cd）染毒后锌（Zn）或铜（Cu）诱导肝脏金属硫蛋白（MT）结合锌镉比值（Zn／Cd）与铜镉比值（Cu／Cd）的关系及其意义。[方法]将28只雄性Wistar大鼠随机分为7组,每组4只,分别为：空白对照组（0）,不做任何处理;非预处理组（A1、A2）,皮下注射生理盐水;Zn处理组（B1、B2）,皮下注射ZnCl2（每千克体重染Zn 25mg）;Cu处理组（C1、C2）,皮下注射CuSO4（每千克体重染Cu 12.5mg）。预处理24h后,为实验组动物皮下注射镉．金属硫蛋白（CdMT,Cdmetallothionein）,造成Cd急性中毒,其中A1、B1、C1组每千克体重染Cd0．1mg,A2、B2、C2组每千克体重染Cd0．4mg。24h后处死,取肝脏,制备匀浆。离心后取上清液,加入SephadexG-75色谱层析柱。[结果]空白对照组动物肝脏中与MT结合的最主要金属元素是Zn,而Cd、Cu含量在检测限以下;与前者相比,A1、A2组动物肝脏MT和Cd含量随染毒剂量增加而升高,且A1、A2组肝脏MT中Zn／Cd值分别为20．0和10．0;B1、B2组肝脏MT中Zn／Cd值分别为20．8和20．3,Cu离子未检出;C1、C2组肝脏MT的Cu／Cd值分别为80．0和36．5,Zn含量下降明显。[结论]不同剂量Cd染毒后,Zn或Cu诱导动物肝脏MT中金属含量比例存在差异,Cu／Cd值高于Zn／Cd值,即与MT结合的Cd相比,Cu更易取代与MT结合的Zn。另外,肝脏中非MT结合Zn也是影响与MT结合的金属离子稳态的重要因素。     

钙通道阻滞剂对钙诱导大鼠肝脏金属硫蛋白的影响

钙通道阻滞剂对钙诱导大鼠肝脏金属硫蛋白的影响ＡｒｉｚｏｎｏＫｅｔａｌ金属硫蛋白（Ｍｅｔａｌｏｌｔｈｉｏｎｅｉｎ，简称ＭＴ）可由重金属、化学药品、激素和应激等多种因素刺激诱导。近来，肝脏ＭＴ被归类于一种急性期蛋白质，这是由于其含量随着动物体正常生理功能...     

乙醇对大鼠脑、肝金属硫蛋白浓度的影响

目的 研究长期乙醇摄入对神经中枢系统的影响，探讨酒精中毒致服损伤的机理。方法 Wistar大鼠每天经灌胃染毒0，10％，30％，50％浓度的乙醇0．5ml，持续2个月。用原子吸收法检测大鼠脑、肝等组织中锌、铜含量；血红蛋白饱和法测金属硫蛋白的含量。结果 长期乙醇摄入后，大鼠脑、肝等组织中金属硫蛋白水平呈上升趋势。雄性大鼠以50％乙醇剂量组的上升效应最明显，大服、小脑、海马、肝、肾中金属硫蛋白水平分别为对照组的2．27，1．53，1．45，1．22，2．58倍（P＜0．05）；雌性大鼠在30％乙醇剂量组上升效应最显，大脑、小脑、海马、肝、肾中金属硫蛋白水平分别为对照组的1．39，3．08，1．75，1．49，1．46倍（P＜0．05）。另外，长期乙醇摄入后，大鼠脑、肝等组织中锌、铜含量均发生明显变化，金属硫蛋白与锌含量的变化呈现明显相关。结论 长期摄入乙醇可诱导大鼠脑、肝金属硫蛋白含量增加，且存在性别差异。     

应激对缺锌和补锌大鼠脂质过氧化的影响

以电击和束缚两种方式建立动物应激模型，观察应激因素对缺锌和补锌大鼠脂质过氧化的影响。结果表明，无论接受电击或束缚应激，缺锌大鼠血浆及肝脏ＬＰＯ含量均显著升高（Ｐ＜０．０１），亦高于补锌动物；接受电击的大鼠肝脏ＭＴ含量显著增加（Ｐ＜０．０１），补锌后增加更明显。结果提示，电击或束缚应激可增强大鼠的脂质过氧化反应，补锌可减轻其应激性氧化损伤     

肠内金属硫蛋白在经口投镉的吸收和分布中的作用

镉是一种重要的职业和环境污染物,通过呼吸道或消化道进入动物和人体内。人类摄取镉的主要形式是吸烟和饮食2条途径。金属硫蛋白(MT)主要存在于小肠、肝脏和肾脏中,其生物学作用之一就是对重金属的解毒。正常小鼠的肠MT含量很低,锌(Zn)和镉均可诱导肠粘膜合成MT。因此本文采用Zn预先诱导小肠产生MT以研究MT对镉吸收和组织分布的影响。动物选用大鼠,随机分成2组,一组为氯化镉染毒组,另一组为对照(氯化镉染毒同时给予锌处理)。研究发现预先经100 mg     

应激对缺锌大鼠免疫功能的影响

目的 观察应激和缺锌双重因素作用下机体免疫功能的变化，并初步了解机体在不同锌水平下的应激反应能力。方法 将Wistar大鼠胺体重随机分为缺锌组（ZD），缺锌应激组（SZD）；对喂组（PF），对喂应激组（SPF）；常锌组（CT），常锌应激组（SCT）。缺锌组以缺锌饲料9锌含量2.0mg/kg），对喂组和常锌组饲以正常饲料（锌含量38.5mg/kg）。喂养1周后，各应激组大鼠接爱光－电刺激，连续15d。然后，取血测定血清皮质醇，取胸腺和脾脏称重，并制备脾脏细胞以测定T细胞增列反应。结果 缺锌或应激时皮质醇含量均明显上升，以缺锌应激组最为明显。缺锌级大鼠食欲减退，生长发育迟缓，出现缺锌体征。应激和非应激条件下，缺锌均可以使胸`腺脾脏萎缩，脏体指数明显下降；各应激组珉春对应的非应激组比较，上述免疫器官的重量和指数均有不同程度的下降，其中，SZD组的胸腺重量和指数、脾脏指数，SPF组的胸腺指数均明显低于对应的非应激组。应激时T细胞增殖能力下降，以缺锌组最为明显。结论 应激和缺锌均可使机体的免疫功能下降；机体锌营养不良使得应激对其免疫功能的损害更为严重。     

补充微量营养素减轻应激损伤的实验研究

目的　观察复合微量营养素对大鼠应激损伤的预防作用。方法　按低、中、高 3种剂量给实验大鼠补充含有维生素、氨基酸和矿物元素的复合营养素 ,以间断足底电击建立动物应激模型 ,检测其旷场行为、应激反应、应激蛋白及抗氧化功能的变化。结果　足底电击诱导的应激反应引起实验大鼠行为异常改变 ,血浆皮质醇浓度升高 ,脑组织儿茶酚胺含量减少。应激动物肝脏和脑组织中的金属硫蛋白含量出现不同程度的变化 ,同时血清总抗氧化能力降低而肝组织脂质过氧化物水平增加。补充 6周微量营养素的应激大鼠行为异常得到逆转 ,上述血液和组织的多数生化指标也出现明显改善。结论　补充复合微量营养素有利于提高实验动物的应激适应能力 ,减轻机体的应激反应损伤     

Effects of isolated zinc deficiency on the composition of skeletal muscle, liver and bone during growth in rats

We investigated the effects of zinc deficiency on body composition by using intragastric force-feeding to obviate decreased food intake and altered eating patterns. Weanling male Sprague-Dawley rats were fed a purified zinc-deficient diet: the ad libitum-fed control group (AL; eight rats) was given powdered diet and water containing 25 ppm zinc; the zinc-replete group (ZN; nine rats) was force-fed a diet blended with water containing zinc in an amount of equal caloric intake to the AL group and allowed access to water containing zinc. The zinc intake of ZN rats was approximately twice that of AL rats based on water intake. The zinc-deficient group (ZD; 13 rats) was fed similarly to the ZN group except deionized water was used for diet preparation and drinking water. After 8 d, body and muscle weight were lower in the ZD group than in the ZN group. Femur weights were similar in the two groups. Serum, liver and femur zinc concentrations were 85, 22 and 42% lower, respectively, in the ZD group than in the ZN group. Serum glucose, relative liver weight, liver glycogen and liver lipids were higher, but muscle and liver DNA were lower in the ZD group than in control groups.     

Chronic vitamin E inadequacy and thermally treated oils affect the synthesis of hepatic metallothionein isoforms

Summary Background: Metallothionein (MT)^# synthesis can be stimulated in many organs not only by various metals such as cadmium, zinc, and copper, but also by many nonmetalic compounds or experimental conditions such as oxidative stress. The latter lead to the hypothesis that MT is induced in response to free radicals formed in tissues and lipid peroxidation. Aims of the study: Whether the relationship between lipid peroxidation amd MT synthesis is a common phenomenon also valid for lipid peroxidation induced by dietary factors such as chronic vitamin E inadequacy and autoxidation products of polyenoic fatty acids derived from thermally oxidized oil was investigated in the presence study. Methods: The relationship between the induction of metallothionein isoforms I and II (MT-I and MT-II) in response to diet-induced lipid peroxidation using a rat model system in which lipid peroxidation was examined in vivo by chronic vitamin E inadequacy or by administration of lipid peroxidation products from a thermally treated polyenoicrich oil with either basal (dietary zinc concentration: 48 mg/kd; experiment 1) or Zn-stimulated MT levels (dietary zinc concentration: 305 mg/kd; experiment 2) was studied. In both experiments, growing male rats were fed diet containing either a fresh or a thermally treated soybean oil with deficient of sufficient amounts of vitamin E (14 and 11 vs. 648 and 560 mg α-tocopherol equivalents per kg diet) over 40 days according to a bifactorial experimental design. Plasma and liver concentrations of tocopherols and hepatic levels of thiobarbituric acid-reacitve substances (TBARS) were measured by high performance liquid chromatography. MT isoform concentrations in rat liver were isolated and quantified by ion-exchange high performance liquid chromatography and atomic absorption spectrometry. Results: Irrespective of the zinc supply, rats receiving inadequate amounts of vitamin E with the diet had markedly lower plasma and liver concentrations of α-tocopherol and total tocopherols than vitamin E-sufficient rats. ANOVA also revealed an interaction between the diet factors vitamin E and oil on tocopherols in plasma and liver of rats from both experiments. In experiment 1, where rats received normal amounts of dietary zinc, ingestion of the thermally treated oil impaired the tocopherol status compared to the treatment with the fresh oil, although this effect was only obvious in the vitamin E-deficient groups. In experiment 2, where rats received excessive amounts of zinc, the thermally treated oil did not contribute to a reduction of the tocopherol status in plasma and liver. In both experiments a significant increase in TBARS level, indicative of lipid peroxidation, was observed in the liver at chronic vitamin E inadequacy, but no effect of the oil was observed. Here, we show that the dietary treatment had some effects on the synthesis of liver metallothionein isoforms. In groups, receiving normal amounts of zinc, there was a significant interaction between the dietary treatments on the levels of MT-I and MT-II in liver. Chronic vitamin E inadequacy which was accompanied by diminisched tocopherol levels in liver induced the synthesis of MT-I and MT-II. When vitamin E inadequacy was combined with the ingestion of a thermally treated polyenoic acid-rich oil hepatic levels of MT-I and MT-II remained low. In experiment 2, where rats were fed the high zinc diet, vitamin E inadequacy caused an increase of hepatic MT-I level just as in experiment 1, although this MT stimulating effect was irrespective of the oil. For MT-II there was a 43% increase in the vitamin E-deficient group fed the fresh oil compared to all the other groups, although this effect was not statistically significant. The liver MT isoform response to stress was similar in rats with basal MT levels and Zn-induced liver MT levels. The failing effect of the thermally treated oil on MT levels which were stimulated by vitamin E deficiency in experiment 2 was possibly due to the low oxidation grade of the thermally treated oil. Conclusion: The present results are strongly indicative of an apparent induction of MT isoform synthesis in response to an impaired antioxidant defence system in the lipid regions of liver cells induced by vitamin E inadequacy. In contrast, thermally treated polyenoic-rich oils with a certain oxidation grade seem to restrain the induction of MT isoform synthesis under the present experimental conditions. Received: 10 January 2000, Accepted: 27 April 2000     

心理应激时大鼠海马神经元的钙状态变化及锌的作用研究

目的 :　研究不同锌营养水平的大鼠在应激条件下的行为变化 ,观察海马细胞内游离钙 ([Ca2 + ]i)及活性钙调素 (Ca M)水平改变 ,以探讨其可能机制。方法 :　大鼠按体重随机分为缺锌组 (ZD)、缺锌应激组 (SZD) ,对喂组 (PF)、对喂应激组 (SPF) ,对照组 (CT)、对照应激组(SCT)。实验进行 1 w后 ,各应激组大鼠接受不规则光 -电刺激 ,2 5 min/ d连续 1 5 d后进行行为测定 ;分别用 Fura-2 / AM双波长荧光法和流式细胞术测定动物海马细胞 [Ca2 + ]i和活性 Ca M水平。结果 :　单纯缺锌大鼠在旷场中的中央格停留时间延长 ,修饰次数减少 ,海马细胞静息 [Ca2 + ]i浓度升高而 Ca M水平下降 ;与相应非应激组比较 ,各应激组大鼠在旷场中的水平和垂直运动减少 ,海马细胞 [Ca2 + ]i含量升高 ,以缺锌应激组最为明显 ;活性钙调素水平则呈相反变化。结论 :　光电应激导致实验大鼠在旷场中行为异常 ,并因机体缺锌而加重 ;推测海马细胞内 Ca2 + -Ca M体系的变化可能是其机制之一     

锌影响鼠脑发育及金属硫蛋白表达的细胞分析

方法：建立低锌、常锌及高锌动物（生后４周及７周）模型，用流式细胞分析技术，对幼鼠脑神经细胞的增殖周期、ＤＮＡ和总蛋白的含量及金属硫蛋白（Ｍｅｔａｌ－ｌｏｔｈｉｏｎｅｉｎ，ＭＴ）的表达进行了测定。结果：低锌组及高锌组与常锌组相比，细胞增殖周期、ＤＮＡ和总蛋白含量及ＭＴ表达有显著差异（Ｐ＜０．０５或Ｐ＜０．０１）。结论：锌明显影响幼鼠脑发育，且与ＭＴ表达密切相关     

Studies of marginal zinc deprivation in rhesus monkeys. III. Use of liver biopsy in the assessment of zinc status

Studies of marginal zinc deficiency in rhesus monkeys have demonstrated that plasma Zn levels are often a poor indication of Zn status. To better assess the Zn status of these animals, we examined their liver concentration of Zn as well as of other minerals, metallothionein (MT), and superoxide dismutase (SOD). Liver-wedge biopsies were obtained from adult rhesus monkeys fed for 15 mo, either a control (100 micrograms Zn/g) or a marginally Zn deficient diet (4 micrograms/g; ZD). Liver Zn and MT concentrations were lower in ZD monkeys than in controls whereas iron concentration was higher in ZD monkeys than in controls. Liver copper, manganese, and magnesium concentrations and activities of CuZnSOD and MnSOD were similar in the two groups. Data from the groups were pooled for regression analysis. Measurement of liver Zn and MT concentrations are useful in the assessment of the effects of long-term Zn deprivation in primates.