Background: Titanium dioxide (TiO2) is currently one of the most widely known nanomaterials produced for different purposes. The adverse effects of nano-dispersed TiO2 cause a serious concern about human health problems related to the intake of TiO2 nanoparticles (TiO2 NPs). The investigation of TiO2 NPs’ penetration through the gut epithelium into secondary organs and the relevant biological effects has an undoubted importance when assessing the potential risk of using TiO2 NPs.

Objective: In the current study, we investigated the effect of rutile TiO2 NPs on tissues of the small intestine, liver, and spleen. For this purpose, we used a physiological model that simulates the single administration of TiO2 NPs directly into the intestinal lumen of an experimental animal.

Methods: Suspensions TiO2 NPs were administered via an isolated loop of the small intestine at a single dose of 250 mg/kg of body weight. TiO2 NPs were detected in rats’ tissues by transmission electron microscopy.

Results: TiO2 NPs were found in tissues of the small intestine mucosa, liver, and spleen. The administration of TiO2 NPs resulted in different changes in the cellular ultrastructures: hyperplasia of the smooth endoplasmic reticulum, an increase in the size of the mitochondria, the emergence of local extensions into the perinuclear space, and the appearance of myelin-like structures.

Conclusion: The ultrastructural changes found in the individual cells of the small intestine, liver, and spleen indicated intracellular pathology, induced by the high doses of the TiO2 NPs. The spleen tissue appeared to be the most sensitive to the effect of TiO2 NPs.

背景技术：二氧化钛（TiO2）当前是最广泛用于不同目的的纳米材料之一。纳米分散的TiO2的不利影响引起人们对与TiO2纳米颗粒（TiO2 NPs）摄入有关的人类健康问题的严重关注。当评估使用TiO2 NPs的潜在风险时，对TiO2 NPs通过肠道上皮渗透至次生器官及其相关生物学效应的研究无疑具有重要意义。

目的：在本研究中，我们研究了金红石型TiO2纳米粒对小肠，肝脏和脾脏组织的影响。为此，我们使用了一种生理模型，该模型模拟了将TiO2 NP直接施用于实验动物的肠腔中的方式。

方法：悬浮液TiO2 NPs通过小肠的一个隔离环以250 mg / kg体重的单剂量给药。通过透射电子显微镜在大鼠组织中检测到TiO2 NPs。

结果：在小肠粘膜，肝脏和脾脏的组织中发现了TiO2 NP。TiO2 NPs的使用导致细胞超微结构发生不同变化：平滑的内质网增生，线粒体大小增加，向核周空间局部延伸的出现以及髓磷脂样结构的出现。

结论：在小肠，肝脏和脾脏单个细胞中发现的超微结构变化表明，高剂量的TiO2 NPs引起细胞内病理变化。脾脏组织似乎对TiO2 NP的作用最敏感。