Comparative Medicine Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina.
National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina.
J Am Assoc Lab Anim Sci. 2020 Mar 1;59(2):212-220. doi: 10.30802/AALAS-JAALAS-19-000068. Epub 2020 Feb 14.
Ulcerative dermatitis in laboratory mice remains an ongoing clinical problem and animal welfare issue. Many products have been used to treat dermatitis in mice, with varying success. Recently, the topical administration of healing clays, such as bentonite and green clays, has been explored as a viable, natural treatment. We found high concentrations of arsenic and lead in experimental samples of therapeutic clay. Given the known toxic effects of these environmental heavy metals, we sought to determine whether the topical administration of a clay product containing bioavailable arsenic and lead exerted a biologic effect in mice that potentially could introduce unwanted research variability. Two cohorts of 20 singly housed, shaved, dermatitis free, adult male CD1 mice were dosed daily for 2 wk by topical application of saline or green clay paste. Samples of liver, kidney and whole blood were collected and analyzed for total arsenic and lead concentrations. Hepatic and renal concentrations of arsenic were not different between treated and control mice in either cohort; however, hepatic and renal concentrations of lead were elevated in clay treated mice compared to controls in both cohorts. In addition, in both cohorts, the activity of δ-aminolevulinate acid dehydratase, an enzyme involved with heme biosynthesis and a marker of lead toxicity, did not differ significantly between the clay-treated mice and controls. We have demonstrated that these clay products contain high concentrations of arsenic and lead and that topical application can result in the accumulation of lead in the liver and kidneys; however, these concentrations did not result in measurable biologic effects. These products should be used with caution, especially in studies of lead toxicity, heme biosynthesis, and renal α2 microglobulin function.
实验小鼠的溃疡性皮炎仍然是一个持续存在的临床问题和动物福利问题。许多产品被用于治疗小鼠的皮炎，但效果不一。最近，已经探索了将愈合粘土（如膨润土和绿粘土）局部应用作为一种可行的天然治疗方法。我们在治疗性粘土的实验样本中发现了高浓度的砷和铅。鉴于这些环境重金属的已知毒性作用，我们试图确定含有生物可利用砷和铅的粘土产品的局部给药是否会对小鼠产生生物学效应，这可能会引入不必要的研究变异性。两批 20 只单独饲养、剃毛、无皮炎的成年雄性 CD1 小鼠，每天通过局部涂抹生理盐水或绿泥糊剂进行为期 2 周的给药。采集肝脏、肾脏和全血样本，并分析总砷和铅浓度。在两个队列中，砷的肝和肾浓度在处理组和对照组小鼠之间没有差异；然而，与对照组相比，粘土处理组小鼠的肝和肾中的铅浓度均升高。此外，在两个队列中，δ-氨基酮戊酸脱水酶的活性（一种与血红素生物合成有关的酶，也是铅毒性的标志物）在粘土处理组小鼠和对照组之间没有显著差异。我们已经证明这些粘土产品含有高浓度的砷和铅，局部应用可导致铅在肝脏和肾脏中积累；然而，这些浓度没有导致可测量的生物学效应。这些产品应谨慎使用，特别是在铅毒性、血红素生物合成和肾α2 微球蛋白功能的研究中。
