Dietary zinc may attenuate heat-induced testicular oxidative stress in mice via up-regulation of Cu-Zn SOD.

Zinc (Zn) is important for male mammalian reproduction. In this study, we sought to clarify the role of Zn in heat-induced testicular damage in mice. Eighteen mice were divided into either control (con), heat (heat) and heat plus Zn (H+Zn) treatment groups, and fed diets containing 60 (con and heat groups) or 300 (H+Zn group) mg/kg Zn sulfate for one month. Mice in the con group were then maintained at 25°C, while mice in heat and H+Zn groups were exposed to 40°C for 2 h daily, for eight days. Mouse testes and serum from each animal were analyzed. Zinc levels in serum and testes were positively correlated to Zn feed concentrations. Mice in the heat group had higher testes index than those in the other two groups (7.22 ± 0.75, heat; 4.92 ± 0.20, con; 4.80 ± 0.30 mg/g, H+Zn; P < 0.05). Testicular antioxidant status showed malondialdehyde levels in heat group mice were increased compared to control mice (2.34 ± 0.15 versus 1.55 ± 0.23 nmol/mg protein; P < 0.05), and Cu-Zn superoxide dismutase (SOD) level differed between heat and H+Zn groups (14.04 ± 0.74 versus 18.27 ± 1.53 U/mg protein; P < 0.05). Testicular Cu-Zn SOD protein expression levels were significantly lower in the heat than in the control group (0.30 ± 0.11 versus 1.22 ± 0.13; P < 0.05). These results suggest that dietary Zn may elevate the activity and protein concentration of Cu-Zn SOD, to attenuate testicular oxidative stress induced by heat exposure.