Distribution And Toxicity Of The Orally-administrated ZnO Nanoparticles In Mice

Zinc oxide nanoparticles (nZnO) are widely used, especially in food and foodpackaging materials, which greatly increase the possibility of nZnO exposure to thepublic. Many studies have been performed on the related biological effects andbiosafety of the orally-administrated nZnO, and a lot of useful data have beenobtained. However, most of animal experiments were done in the normal animalmodels. How the physiological status affects the distribution and toxicity oforally-administrated nZnO in vivo still remains unknown.Taking into account that intestinal diseases affect the absorption of variousnutrients, we used indomethacin to induce the intestinal injury in mice, and studiedthe distribution and toxicity of nZnO in the intestinal-damaged mice. After theintestinal injury mice were developed, they were exposed to nZnO and ZnOmicroparticles (mZnO) by gavage.The mice were sacrificed at4-24hours postexposure, blood and organs were collected. The serum was separated for thedetection of biochemical parameters; kidneys, liver and small intestine were fixedfor the pathological examination; Tissues were digested for the distribution detectionof zinc, iron and copper in mice by inductively coupled plasma mass spectrometry;the synchrotron radiation techniques were used to observe the distribution of zincand other elements in the intestinal villi.Both the normal and intestinal-damaged ICR mice adsorbed ingested ZnO, andthe size affected the distribution of zinc oxide. Compared with the normal group,higher accumulation of nZnO was observed in the blood, liver, kidneys, spleen andsmall intestine in the intestinal-damaged group. Under the condition of intestineinjury, higher uptake of Zn was found in the blood, kidneys, spleen, lungs and smallintestine in the nZnO group than the mZnO group, but the zinc content in the liver inthe mZnO group was higher than that in the nZnO group. The results obtained fromthe synchrotron radiation measurements approved the findings. The content level of iron and copper was affected by the ZnO exposure, but now largely afftect by theintestine injury and the size of particle. The intestinal damage had little on influencethe serum biological parameter and pathological changes induced by the ZnOexposure, indicting the low toxicity of orally-administrated nZnO, though the levelof ALT changed.The intestinal injury affected the uptake of orally-administrated ZnOnanoparticles. Further researches are necessary to address the effect of thephysiological status on the nanoparticle uptake and the related mechanism. Our workindicates that more attentions should be paid to study the nanoparticle uptake andtoxicity in vivo in the disease models.