Experimental switching of copper status in laboratory rodents

There is an emerging link between copper metabolism, tumor growth and efficiency of antitumor treatment with platinum drugs or copper chelators. So there is an urgent need for well-defined and reproduced animal models with different states of copper metabolism. In the present study an animal model (rats and mice) with switching copper status in blood serum (copper concentration, oxidase activity and ceruloplasmin (Cp) protein content) is characterized. The drop of copper status is caused by addition of AgCl to fodder (Ag-animals). In rats and mice, the influence of silver ions on oxidase and ferroxidase activity of blood serum is similar, but copper concentration is reduced by 90% in rats, and by 60% in mice. The absorbed silver ions are transported to liver cells and included to Cp polypeptides, which are secreted to blood serum then. Cp, which circulates in bloodstream of Ag-animals contains silver atoms, and is misfolded, as judged by circular dichroism spectroscopy and differential scanning calorimetry. Single intraperitoneal or per oral injection of Cu(II) salt to Ag-animals causes recovery of oxidase and ferroxidase activity of blood serum within 4 hours in both rodent species, presumably by rapid metabolic insertion of copper into forming Cp in liver. The recovered copper status persists for 3 days under the continuing Ag-diet. The possibilities of use of Ag-rodents with switching copper status in investigation of influence of copper status on tissue-specific intracellular copper metabolism and role of copper in tumor genesis, bone metabolism and neurodegenerative diseases are discussed.