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 z inc supplementation inhibited this process. The aim of this study was to investigate the effect of dietary zinc on malondialdehyde (MDA) pro duct as an index of endogenous lipid peroxidation, glutathione (GSH) a nd protein thiols (PrSHs) as well as superoxide dismutase (SOD) activi ty in rat blood, liver and pancreas. Young male rats were fed a zinc d eficient (ZD) basal diet containing similar or equal to 0.5 ppm zinc o r were fed ad libitum (AL) a zinc adequate diet (30 ppm zinc) for 3 we eks. 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 concentra tion of the investigated tissues reflected the dietary zinc content. P lasma, liver and pancreas MDA measurements from ZD rats revealed signi ficant increases (P < 0.05, <0.001) as compared to AL control values, the highest increase was in pancreas. ZD rats also displayed significa nt 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 com pared to AL control values. However, these measurements in pancreas we re insignificantly changed except GSH content was significantly increa sed (P < 0.05). Feeding ZD rats a diet containing 100 ppm or 1000 ppm zinc resulted in a significant reduction of the endogenous MDA formati on (P < 0.05, < 0.001) in their tissues with the reversal of changes i n the other parameters, so that their levels were nearly restored to A L control values especially in response to 1000 ppm zinc. This study s hows that zinc deficiency led to a large increase in MDA content of bl ood, liver and pancreas with an accompanied alteration of the antioxid ant systems. Feeding ZD rats with 1000 ppm zinc reversed these changes nearly to AL control values. It is concluded that zinc possesses an a ntioxidant property and has a role in controlling lipid peroxidation.