Effect of dietary zinc on lipid peroxidation, glutathione, protein thiols levels and superoxide dismutase activity in rat tissues.

Dietary zinc deficiency can cause increased lipid peroxidation while zinc supplementation inhibited this process. The aim of this study was to investigate the effect of dietary zinc on malondialdehyde (MDA) product as an index of endogenous lipid peroxidation, glutathione (GSH) and protein thiols (PrSHs) as well as superoxide dismutase (SOD) activity in rat blood, liver and pancreas. Young male rats were fed a zinc deficient (ZD) basal diet containing congruent to 0.5 ppm zinc or were fed ad libitum (AL) a zinc adequate diet (30 ppm zinc) for 3 weeks. The ZD rats were then fed the basal diet supplemented with either 100 ppm zinc or 1000 ppm zinc for another 3 weeks. The zinc concentration of the investigated tissues reflected the dietary zinc content. Plasma, liver and pancreas MDA measurements from ZD rats revealed significant increases (P < 0.05, < 0.001) as compared to AL control values, the highest increase was in pancreas. ZD rats also displayed significant decreases in their blood and liver GSH content (P < 0.001, < 0.05) and SOD activity (P < 0.001) as well as serum PrSHs (P < 0.001) as compared to AL control values. However, these measurements in pancreas were insignificantly changed except GSH content was significantly increased (P < 0.05). Feeding ZD rats a diet containing 100 ppm or 1000 ppm zinc resulted in a significant reduction of the endogenous MDA formation (P < 0.05, < 0.001) in their tissues with the reversal of changes in the other parameters, so that their levels were nearly restored to AL control values especially in response to 1000 ppm zinc.(ABSTRACT TRUNCATED AT 250 WORDS)