S. Toyokuni et Jl. Sagripanti, INCREASED 8-HYDROXYDEOXYGUANOSINE IN KIDNEY AND LIVER OF RATS CONTINUOUSLY EXPOSED TO COPPER, Toxicology and applied pharmacology, 126(1), 1994, pp. 91-97
Copper is a ubiquitous metal in the environment, it is a component of
dental casting gold alloys and dental amalgams, and it is a main compo
nent in some intrauterine contraceptive devices (IUDs). Since copper m
aterials implanted in the human body corrode and release ions into the
surrounding tissue, the potential toxicity caused by contact of this
metal with bodily fluids needs to be evaluated. We implanted male Wist
ar rats with osmotic mini pumps that continuously administered saline,
CuCl2, or a copper chelate, cupric nitrilotriacetate (Cu-NTA), at a r
ate of 4 mg copper/kg body wt/day. This experimental design maintained
serum copper concentrations at a level 30-70% (CuCl2) or 100-120% (Cu
-NTA) higher than in untreated controls. At different times postimplan
tation, we measured the levels of 8-hydroxydeoxyguanosine (8-OHdG) in
DNA of kidney, liver, and tissue surrounding the pump implant, since p
roduction of 8-OHdG has been associated with mutagenesis and carcinoge
nesis. Hepatic and renal levels of 8-OHdG in CuCl2- or Cu-NTA-treated
animals were significantly higher than in control animals. In contrast
, histopathologic changes in kidneys and livers of rats exposed to CuC
l2 and Cu-NTA were limited to mild changes involving hepatic focal nec
rosis and slightly increased mitotic activity in the renal proximal tu
bules. These observations suggest that levels of 8-OHdG could be an ea
rly marker of copper toxicity. It is unlikely that the high levels of
copper at which we observed DNA modification will be encountered after
occupational or environmental exposure. A different situation could b
e found around medical devices that include copper, particularly IUDs,
where the amount of copper administered in our experiments could be r
eleased in the uterus of women after a few months of continued IUD use
. (C) 1994 Academic Press, Inc.