权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Role of fetal metallothionein against mercury toxicity after exposure to mercury vapor

胎儿金属硫蛋白在接触汞蒸气后对抗汞毒性的作用

基本信息

批准号：
14570307
负责人：
YOSHIDA Minoru
金额：
$ 2.56万
依托单位：
St.Marianna University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

(1) Behavioral effects of low levels of exposure to mercury vapor in metallothionein-null miceWe studied the neurobehavioral effects of prolonged exposure to low concentrations of mercury (Hg^o) vapor and the role of metallothionein (MT) isoforms present in the brain on the behavioral neurotoxicity caused by mercury. MT-null mice that do not express MT-I and -II genes and wild type mice were exposed to Hg^o vapor at 0.031-0.119 mg/m^3 for 6hr per day for 23 weeks. The behavioral effects were evaluated with an open field test and passive avoidance tasks at 12 and 23 weeks after exposure. At 12 weeks, total locomotor activity in the open field test reached hyperactive levels in both strains, but the passive avoidance behavior was un-affected. In the behavioral test performed at 23 weeks, a significant increase in locomotor activity and a learning disability in the passive avoidance response test were observed in the exposed MT-null mice as compared with the controls. However, the concent … More ration of mercury in the brain was significantly lower in MT-null mice than wild type mice and the nervous tissues of MT-null mice were also normal on histochemical evaluation. Brain MT levels were higher in wild type than MT-null mice following prolonged exposure to Hg^o vapor. These results suggest that MT-I and -II in the brain play an important role in the behavioral changes produced following exposure to Hg^o vapor.(2) Neurobehavioral changes in metallothionein-null mice prenatally exposed to mercury vaporWe studied the neurobehavioral effects of prenatal exposure of MT-null ad wild-type mice following prenatal exposure to elemental mercury vapor (Hg^o). Both strains of pregnant mice were repeatedly exposed to Hg^o vapor at 0.50 and 0.56 mg/m^3 for 6h per a day until 18th day from gestation. The behavioral effects were evaluated with locomotor activity in the open field, learning ability in the passive avoidance response and spatial learning ability in the Morris water maze at 12 weeks of age. Hg^o-exposed MT-null mice showed a significant decrease in total locomotor activity in males, and a learning disability in the passive avoidance response and a retarded acquisition in the Morris water maze in females as compared with the control. On the contrary, Hg^o-exposed wild-type mice did not differ from controls on three behavioral measurements. The results indicate that MT-null mice would be more susceptible than wild-type mice to the behavioral neurotoxcity of prenatal Hg^o exposure. Especially, hippocampus involving a learning performance of MT-null female mice may be significantly affected by mercury compared with male of same strain. From these results, it is considered that MT-I and -II in fetal brain has a role preventing the behavioral effects caused by prenatal exposure to Hg^o. Less

(1)低浓度汞蒸气暴露对金属硫蛋白缺失小鼠的行为影响研究了长期暴露于低浓度汞蒸气对神经行为的影响，以及脑内金属硫蛋白（MT）亚型在汞引起的行为神经毒性中的作用。不表达MT-I和-II基因的MT-null小鼠和野生型小鼠每天暴露于0.031-0.119 mg/m^3的Hg^o蒸气中6小时，持续23周。暴露后12周和23周，通过开放场测试和被动回避任务评估行为影响。12周时，两个品系在野外测试中的总运动活动达到了过度活跃的水平，但被动回避行为没有受到影响。在23周进行的行为测试中，与对照组相比，暴露MT-null小鼠的运动活动和被动回避反应测试中的学习障碍明显增加。然而，MT-null小鼠脑内汞含量明显低于野生型小鼠，MT-null小鼠的神经组织在组织化学评价上也正常。在长时间暴露于Hg^o蒸气后，野生型小鼠的脑MT水平高于MT-null小鼠。这些结果表明，大脑中的MT-I和-II在暴露于Hg^o蒸汽后产生的行为变化中起着重要作用。(2)金属硫蛋白缺失小鼠的神经行为变化我们研究了mt -缺失小鼠和野生型小鼠在产前暴露于单质汞蒸气（Hg^o）后的神经行为影响。两株妊娠小鼠分别以0.50和0.56 mg/m^3的浓度反复暴露于Hg^o蒸汽中，每天6小时，直至妊娠第18天。通过对12周龄大鼠开放场地的运动活动、被动回避反应的学习能力和Morris水迷宫的空间学习能力评价其行为效果。与对照组相比，Hg^o暴露的MT-null小鼠的雄性总运动活动显著减少，在被动回避反应中出现学习障碍，在莫里斯水迷宫中出现习得迟缓。相反，暴露于Hg^o的野生型小鼠在三个行为测量上与对照组没有差异。结果表明，mt缺失小鼠比野生型小鼠更容易受到产前汞暴露的行为神经毒性影响。特别是，与同品系的雄性小鼠相比，MT-null雌性小鼠的海马涉及学习性能可能受到汞的显著影响。由此可见，胎儿脑内MT-I和-II具有预防产前汞暴露引起的行为影响的作用。少