Reduction of copper and metallothionein in toxic milk mice by tetrathiomolybdate, but not deferiprone.

Copper is both essential for life and toxic. Aberrant regulation of copper at the level of intracellular transport has been associated with inherited diseases, including Wilson's disease (WND) in humans. WND results in accumulation of copper and the copper and zinc-binding protein metallothionein (MT) in liver and other tissues, liver degeneration, and neurological dysfunction. The toxic milk (TX) mutation in mice results in a phenotype that mimics human WND, and TX has been proposed to be a model of the disease. We characterized TX mice as a model of altered metal ion and MT levels during development, and after treatment with the metal ion chelators tetrathiomolybdate (TTM) and deferiprone (L1). We report that hepatic, renal and brain copper and MT are elevated in TX mice at 3 and 12 months of age. Zinc was significantly higher in TX mouse liver, but not brain and kidney, at both time points. Nodules appeared spontaneously in TX mouse livers at 8-12 months that maintained high copper levels, but with more normal morphology and decreased MT levels. Treatment of TX mice with TTM significantly reduced elevated hepatic copper and MT. Transient increases in blood and kidney copper accompanied TTM treatment and indicated that renal excretion was a significant route of removal. Treatment with L1, on the other hand, had no effect on liver or kidney copper and MT, but resulted in increased brain copper and MT levels. These data indicate that TTM, but not L1, may be useful in treating diseases of copper overload including WND.