Cadmium-induced testes oxidative damage in rats can be influenced by dietary zinc intake

We tested the hypothesis that zinc deficient animals would be characterized by an increased sensitivity to cadmium-induced oxidative damage to the testes. Weanling male rats were given free access to either a control (25 microg Zn/g) or a zinc deficient (0.5 microg Zn/g) diet; or restricted access to the 25 microg Zn/g diet at a level of intake similar to that of rats fed the 0.5 microg Zn/g diet. After 14 days on the diets, animals were injected s.c. with either saline or CdCl2 (2 mg Cd/kg body weight) solutions, and killed 24 h later. In the zinc-deficient group, testes weight and testes/body weight were higher in the cadmium-injected rats than in the saline-injected rats. The extent of hemorrhages, as indicated by high hemoglobin and testes iron concentrations was higher in the cadmium-treated zinc deficient group than in the cadmium-injected controls. In the zinc-deficient group, cadmium injection was associated with higher levels of lipid peroxidation (33% higher TBARS content) and protein oxidation (17% lower glutamine synthetase activity). Cadmium injection did not influence these parameters in the zinc-adequate groups. Extracellular superoxide dismutase activity was lower in the zinc-deficient group than in the zinc-sufficient groups; there was a trend (P < 0.06) for a lower activity in the cadmium- versus the saline-injected rats. These results support the concept that zinc deficiency increases the susceptibility of testes to cadmium-mediated free radical damage.