Subcellular changes of essential metal shown by in-air micro-PIXE in oral cadmium-exposed mice.
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.
Nakazato
Kyoumi
K
School of Health Sciences, Faculty of Medicine, Gunma University, 3-39-15 Shouwa-machi, Maebashi, Gunma 371-8514, Japan. nkyoumi@health.gunma-u.ac.jp
Nagamine
Takeaki
T
Suzuki
Keij
K
Kusakabe
Takahiko
T
Moon
H D
HD
Oikawa
Masakazu
M
Sakai
Takuro
T
Arakawa
Kazuo
K
D000284:Administration, Oral; D000818:Animals; D002104:Cadmium / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007150:Immunohistochemistry; D007501:Iron / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008668:Metallothionein / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D015032:Zinc / Q000378:metabolism
D002104:Cadmium; D008668:Metallothionein; D007501:Iron; D015032:Zinc