ZINC-DEFICIENCY CAUSES OXIDATIVE DAMAGE TO PROTEINS, LIPIDS AND DNA IN RAT TESTES

To investigate the effects of zinc deficiency on oxidative damage to testes proteins, lipids and DNA, weanling male rats were allowed free access to low (0.5 mu g Zn/g) or adequate (25 mu g Zn/g) zinc diets for 14 d. A third group was restricted intake of the adequate Zn diet to the amount consumed by the low Zn diet-fed group. Compared with ad libitum-fed controls, testes from rats fed the low zinc diet had lower glutamine synthetase activity, lower Fe2+-stimulated 2-thiobarbituric acid-reactive substances (TEARS) production, higher protein carbonyl concentrations (P < 0.05), and higher 8-oxo-2'-deoxyguanosine levels (P = 0.06). Glutamine synthetase activity in testes of the food-restricted controls was between the values for the ad libitum controls and zinc-deficient animals. Protein carbonyls were higher in the restricted controls compared with the ad libitum controls, whereas stimulated TEARS production was lower (P < 0.05). Levels of 8-oxo-2'-deoxyguanosine were lower in testes DNA of the restricted controls than in the zinc-deficient group (P < 0.05). Testes iron concentrations were higher in the zinc-deficient and restricted control rats than in ad libitum controls (P < 0.05). The oxidative damage observed may have occurred as a consequence of increased reactive oxygen species generation secondary to tissue iron accumulation and/or reductions in zinc-dependent antioxidant processes.