Effect of acute administration of cadmium on distribution of zinc in the hamster

Effects of mine waste water on rat: bioaccumulation and histopathological evaluation

The highlighting of the bioaccumulation capacity of metals in the internal organs, the mode of distribution at the level of internal organs, the interactions between them, respectively, and the histological changes occurred at the level of the liver and kidneys are the main aspects addressed in the present study. The experiment was performed on 4 groups of Wistar rats: 3 groups which were administered water from rivers located in the vicinity of the Bor mining operation and 1 control group. The determination of the metal content in the administered water samples and in the internal organs was performed using the flame atomic absorption spectrophotometer. Tissue alterations were assessed by histological technique and hematoxylin-eosin staining. The metal retention capacity in the internal organs differs depending on the metal concentration in the administered water sample but also on the organ in which the determination was made. Also, correlations were established between the concentrations of metals at the level of the organs, showing (a) positive and significant correlations-at the level of the heart between Zn and Cu, Fe, and Mn and at the level of the lungs between Mn and Cd-but the most numerous were reported in the testicle; (b) moderate correlations at liver level between Fe and Zn, at spleen level between Cu and Mn and Cd and at the level of the kidneys between Pb and Zn, Cu, and Fe; (c) negative correlations at renal level between Pb and Mn; and (d) insignificant correlations between Pb and Fe. The histological changes identified at the level of the liver and kidney become more obvious, and their aggravation is registered with the increase of the metal content.

Protective effects of selenium (Se) and zinc (Zn) on cadmium (Cd) toxicity in the liver and kidney of the rat: histology and Cd accumulation

To assess the co-effect of Se and Zn on Cd accumulation in the liver and kidney and on their histology, male rats were exposed either to Cd, Cd+Zn, Cd+Se, or Cd+Zn+Se in their drinking water, during 35 days. Exposure to Cd resulted in its accumulation in the liver and kidney. In the Cd-Zn and Cd-Zn-Se groups, Cd contents in the two organs were significantly (p < 0.01) higher than those in the Cd group. Se did not induce any significant difference in hepatic and renal concentrations of Cd in comparison to Cd-treated group. Light microscopic examination indicated severe histological changes in the two organs under Cd influence. Se or Zn partially alleviated the damage observed in the liver. The same effect was remarked in the kidney with Se, but no differences in the renal histological structure have been observed between the Zn-Cd and the control groups. With Se and Zn simultaneous treatment during Cd exposure, the observed morphological changes had practically disappeared from the liver, but were only reduced in the kidney.

CONCLUSION

Se and Zn can have a cooperative effect in the protection against Cd-induced structural damage in the liver but not in the kidney.

Effects of zinc deficiency on pre-existing cadmium-metallothionein in the pancreas

Although the injection of cadmium salts increases the metallothionein (MT) concentration in a number of organs, including pancreas, the induced synthesis of pancreatic metallothionein was specifically decreased in zinc deficiency. The fate of Cd-induced metallothionein and the change in tissue distribution of Zn and Cd were studied with the onset of Zn deficiency. Rats were repeatedly injected with CdCl2 to induce MT synthesis, and were subsequently made Zn deficient. The lability of the pancreatic Zn pool, as compared with that of liver and kidney, was demonstrated. During Zn deficiency, there was little change in Cd concentration or MT level in either liver or kidney. When Zn deficiency led to a decrease in pre-existing pancreatic MT, Cd was not eliminated from the pancreas, but was transferred to a high molecular weight fraction. On the basis of these results we suggest that the presence of Cd-Zn-MT has little effect on the eventual pancreatic Zn and MT contents, during subsequent Zn deficiency.