No effects of low copper intake on rat mammary tissue superoxide dismutase 1 activity and mammary chemical carcinogenesis.

Variations in copper-containing superoxide dismutase (SOD) 1 are hypothesized to produce variations in resistance to carcinogenesis, particularly in mammary tissue. Therefore, it is reasonable to speculate that low copper intake, which causes low SOD 1 activities in various tissues, would cause poor resistance to mammary carcinogenesis. This idea was tested using female rats fed diets either low or adequate in copper (< 0.5 or 8 mg copper/kg diet) plus or minus oral gavage with the mammary carcinogen 7,12-dimethylbenz[a]anthracene (5 mg/kg, given 5 wk after dietary modification, 28 wk before sacrifice). Low copper intake produced low activities of two serum copper enzymes: ceruloplasmin and extracellular SOD. In contrast, low copper intake did not affect mammary tissue SOD 1 activities, nor did it statistically influence any of several parameters of 7,12-dimethylbenz[a]anthracene-induced mammary carcinogenesis.