Physiological Effects of Natural or Contaminating Compounds in a Rodents Microenvironment

国家环境健康科学研究所(NIEHS)比较医学分部的质量保证实验室(QAL)对整个NIEHS研究计划的关键方面的微生物和/或化学污染进行测试。我们的主要任务是监测动物研究计划中可能影响动物健康和福利的微生物和/或化学污染，以及研究研究中使用的动物的生理反应。 我们的研究集中在研究动物的微环境(如动物饲料、笼子、被褥、水等)中天然或污染化合物的生理效应。我们的目标是确保我们最大限度地减少接触环境化合物，这些化合物可能会影响动物的健康和福利，或者改变动物的生理反应，导致不可接受的可变性。 从历史上看，QAL研究的重点是研究动物微环境中存在的内分泌干扰化合物(EDCs)的可能性，以及这些化合物可能对研究结果，特别是生殖发育的影响。在这些研究中，青春期前的CD-1小鼠在出生后第15天(PND)断奶，从PND 15到PND 35口服(通过饮食、水或灌胃)测试化合物，或者直到发生阴道开放(VO)，这是受激素影响的发育里程碑。我们已经证明，商业上可获得的啮齿动物饲料中存在的天然植物雌激素(如大豆苷元和染料木素)或添加到不含这些化合物的饲料中可以显著(P<0.01)加快CD-1小鼠的VO时间。我们还表明，饮食中的总代谢能(ME)可以显著影响这些激素敏感的终点，尽管这个变量的可预测性不如植物雌激素含量。我们已经证明，雌激素真菌毒素玉米赤霉烯酮在商业上可获得的玉米芯垫料中普遍存在。189个样本中有154个(84%)受到玉米赤霉烯酮的天然污染，污染水平从100到7,000 ppb(平均500 ppb)不等。我们已经证明，5-10ppm的水平可以显著延长CD-1有毛和SKH-1无毛未成熟小鼠的VO时间。 我们目前正在进行研究，研究高压灭菌对啮齿动物饲料的物理和化学性质的影响。啮齿动物饲料的灭菌对于防止可能改变动物健康或生理反应的微生物的引入是很重要的，而高压灭菌是一种广泛使用的方法。以前的研究发现，高压灭菌的啮齿动物饲料会产生丙烯酰胺，任何高淀粉含量的食物(如土豆、面包等)都会产生丙烯酰胺。这些研究还确定，高压灭菌饲料产生的丙烯酰胺水平足够高，足以引起可测量的遗传毒性效应(DNA加合物)。我们的研究确定，提高灭菌温度会导致颗粒饲料的利用率增加，以及丙烯酰胺的浓度增加。我们目前正在测量这些水平的丙烯酰胺在体内的影响。

The Quality Assurance Laboratory (QAL) in the Comparative Medicine Branch at the National Institute of Environmental Health Science (NIEHS)performs testing on the microbiological and/or chemical contamination of critical aspects of the overall NIEHS research program. Our primary task is monitoring the animal research program for microbiological and/or chemical contamination that may affect animal health and welfare, as well as, the physiological responses of animals used in research studies. Our research focuses on the physiological effects of natural or contaminating compounds in the micro-environment (e.g., animal feed, caging, bedding, water, etc.)of the research animals. Our goal is to assure that we minimize exposure to environmental compounds that may effect animal health and welfare or alter physiological responses of the animals resulting in unacceptable variability. Historically, QAL studies have focused on the potential for endocrine-disrupting compounds (EDCs) being present in the micro-environment of the research animals and the impact these compounds may have on study outcomes, especially reproductive development. For these studies, pre-pubertal CD-1 mice are weaned at post-natal day (PND) 15 and given test compounds orally (via diet, water or gavage) from PND 15 to PND 35 or until vaginal opening (VO) occurs which is a developmental milestone affected by hormones. We have shown that natural phytoestrogens (e.g., daidzein and genistein) present in commercially available rodent diets or added to diets free of these compounds can significantly (P less than 0.01) accelerate the time of VO in CD-1 mice. We have also shown that the total metabolizable energy (ME) in the diet can significantly affect these hormone-sensitive endpoints, although the predictability of this variable was less powerful than the phytoestrogen content. We have shown that the estrogenic mycotoxin zearalenone is ubiquitious in commercially available corn-cob bedding. 154 of 189 (84%) of the samples were naturally contaminated with zearalenone at levels ranging from 100 to 7,000 ppb (mean 500 ppb). We have shown that levels of 5-10 ppm can significantly advance the time of VO in immature CD-1 haired and SKH-1 hairless mice. We are currently performing studies looking at the effects of autoclave sterilization of rodent feed on the physical and chemical properties of the feed. Sterilization of rodent feed is important to prevent the introduction of microorganisms that may alter animal health or physiological response, and autoclave sterilization is a widely used method. Previous studies found that autoclaving rodent feed resulted in the production of acrylamide, as does any high starch containing food (e.g., potatoes, breads, etc.). These studies also determined that the levels of acrylamide produced by autoclaving the feed were high enough to cause measurable genotoxic effects (DNA adducts). Our study determined that increasing the sterilization temperature used resulted in an increase in the harness of the pelleted feed, as well as, the concentration of acrylamide. We are currently measuring the in-vivo effects of these levels of acrylamide.