Hepatic and Renal Toxicity Induced by TiO₂ Nanoparticles in Rats: A Morphological and Metabonomic Study

Figure 5

Morphology of the kidney in control rats (a, e) or in animals exposed to TiO₂ nanoparticles (16g/kg) and sacrificed after 4 days (b-d, f-h). (a-d) Paraffin sections stained with PAS, hemalun, Luxol fast blue; (e-f) detection by immunocytochemistry of 4-hydroxynonenal (4-HNE). As compared to controls (a), kidney cortex of TiO₂ exposed animals (b) presents generally a low level of histopathological alterations. These focal alterations are characterized by apoptotic nuclei (arrows) in proximal convoluted tubules (PT) and in collecting ducts (CD) and by the presence of PAS-positive material in the lumen of some collecting ducts (arrow head). Images of mitosis (large arrow) are frequently observed in proximal tubules. Presence of necrotic tubules (NT) characterized by a desquamation of tubular epithelium and the presence of large TiO₂ aggregates in lumens are exceptional (c). The outer stripe of outer medulla (OSOM) (d) is also poorly impacted by the treatment. Proximal strait tubules (S3 segments) have a normal morphology. Only collecting ducts (CD) present some PAS-positive cytoplasmic inclusions (arrow heads) and exceptionally necrotic cells in the lumen (arrow). 4-HNE immunoreactivity is not present in controls (e) and is only detected in a few numbers of tubules (arrows) in treated animals (f). At high magnification (g, h) these positive tubules are identified as collecting ducts (arrow heads) and distal tubules (arrow). Glom: glomeruli; DT: distal tubules.

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