Subcellular changes of essential metal shown by in-air micro-PIXE in oral cadmium-exposed mice

• Published in: Biometals 2008-02, Vol.21 (1), p.83-91
• Main Authors: Nakazato, Kyoumi, Nagamine, Takeaki, Suzuki, Keij, Kusakabe, Takahiko, Moon, H. D, Oikawa, Masakazu, Sakai, Takuro, Arakawa, Kazuo
• Format: Article
• Language: English
• Subjects: Administration, Oral; Animals; Biochemistry; Biomedical and Life Sciences; Cadmium; Cadmium - administration & dosage; Cadmium - pharmacology; Carcinogens; Cell Biology; Drinking water; Female; Hepatotoxicity; Immunohistochemistry; In-air micro-PIXE; Iron; Iron - metabolism; Kidney - drug effects; Kidney - metabolism; Life Sciences; Liver; Liver - drug effects; Liver - metabolism; Medicine/Public Health; metallothionein; Metallothionein - metabolism; Mice; Mice, Inbred ICR; Microbiology; Pharmacology/Toxicology; Plant Physiology; Spectrometry, X-Ray Emission - methods; Toxicity; Zinc; Zinc - metabolism
• ISSN: 0966-0844; 1572-8773
• DOI: 10.1007/s10534-007-9095-6

To clarify the relation of essential metals to cadmium (Cd) toxicity, we evaluated metallothionein expression and analyzed the subcellular distribution of essential metals using in-air micro-Particle-Induced X-ray Emission (PIXE). Four mice were dosed orally with 100 mg/L of Cd in drinking water for 1.5 or 2 years. Frozen samples of organs were used for micro-PIXE analysis and formalin-fixed samples were used for metallothionein staining. Immunohistochemically, metallothionein induction by 1.5y-Cd exposure was higher in the renal cortex than in the liver. Metallothionein expression was reduced after 2y-Cd administration compared to the 1.5y-Cd-exposed mice. Cd-induced tissue damage became marked in the 2y-Cd-exposed mice compared to the 1.5y-Cd-exposed mice, in which nephrotoxicity was more prominent than hepatotoxicity. Cd yield was higher in the renal cortex of the 2y-Cd-exposed mouse than in that of the 1.5y-Cd-exposed mouse, whereas no such increasing tendency was found in the liver. Compared to the control, the Cd-exposed mice markedly accumulated zinc in the liver and renal cortex. In the Cd-exposed mice, iron was mildly accumulated in the renal cortex and was slightly deprived in the liver. Elemental maps showed that a large amount of Cd was spatially combined with zinc in the 1.5y-Cd mouse. Free Cd became abundant in the 2y-Cd-exposed mouse. In addition, a small amount of Cd was colocalized with iron. The data suggest that zinc may contribute to protect against oral-administrated Cd toxicity, and impaired induction of MT may participate in hepato-nephrotoxicity of the 2y-Cd-exposed mouse.