Dietary docosahexaenoic acid enhances ferric nitrilotriacetate-induced oxidative damage in mice but not when additional alpha-tocopherol is supplemented

The Role of Ferric Nitrilotriacetate in Renal Carcinogenesis and Cell Death: From Animal Models to Clinical Implications

Iron is essential for cellular growth, and various ferroproteins and heme-containing proteins are involved in a myriad of cellular functions, such as DNA synthesis, oxygen transport, and catalytic reactions. As a consequence, iron deficiency causes pleiotropic effects, such as hypochromic microcytic anemia and growth disturbance, while iron overload is also deleterious by oxidative injury. To prevent the generation of iron-mediated reactive oxygen species (ROS), ferritin is synthesized to store excess iron in cells that are consistent with the clinical utility of the serum ferritin concentration to monitor the therapeutic effect of iron-chelation. Among the animal models exploring iron-induced oxidative stress, ferric nitrilotriacetate (Fe-NTA) was shown to initiate hepatic and renal lipid peroxidation and the development of renal cell carcinoma (RCC) after repeated intraperitoneal injections of Fe-NTA. Here, current understanding of Fe-NTA-induced oxidative stress mediated by glutathione-cycle-dependent iron reduction and the molecular mechanisms of renal carcinogenesis are summarized in combination with a summary of the relationship between the pathogenesis of human RCC and iron metabolism. In addition to iron-mediated carcinogenesis, the ferroptosis that is triggered by the iron-dependent accumulation of lipid peroxidation and is implicated in the carcinogenesis is discussed.

Modulation of antioxidant defence system by dietary fat in rats intoxicated with o-toluidine

o-Toluidine was administered to rats in the diet for four weeks at levels approximately 40, 80 and 160 mg/kg b.w. per day. Two types of diet have been used, standard (4% fat) and high fat (14% fat). Activity of antioxidant enzymes, level of glutathione and thiobarbituric acid reactive substances were measured in liver. Glutathione peroxidase was significantly increased in all treated groups while glutathione S-transferase and glutathione reductase were elevated in rats fed high-fat diet. o-Toluidine slightly enhanced catalase activity regardless of the kind of diet. Superoxide dismutase was the only enzyme whose activity was lowered in almost all treated groups. Enzymatic and nonenzymatic microsomal lipid peroxidation was enhanced 2- to 3-fold in both diet groups. Reduced glutathione level in liver was 2.3- to 4.0-fold increased in all treated groups. Our findings indicate that free radical processes can be involved in the toxic effects of o-toluidine and dietary fat can modify the response of some antioxidant enzymes to this compound.

The effect of ferric-nitrilotriacetic acid on the profile of polyunsaturated fatty acids in the kidney and liver of rats

Intraperitoneal injection of the iron-complex, ferric-nitrilotriacetate (Fe-NTA), induces renal proximal tubular damage associated with oxidative damage in vivo. Fe-NTA induced a time-dependent decrease of several polyunsaturated fatty acids (PUFA), together with increased conjugated diene values and decreased cellular levels of alpha-tocopherol and glutathione. At the time of maximum detectable oxidation (3 h), after the injection of a sublethal dose of Fe-NTA there were clear reductions in the peak values over the controls for several fatty acids notably, 20:5 (eicosapentaenoic acid) (36%), 22:6 (docosahexanoic acid) (30%), 20:3 n6 (eicosatrienoic acid) (30%) and 20:4 (arachidonic acid) (28%) in the kidney. Fewer fatty acids showed a reduction in their residual values in the liver. 20:5 was reduced by 45% and for the 18:3 n3 and 18:3 n6, reductions of 35%, respectively. The profile of PUFAs is sensitive to the oxidative damage due to Fe-NTA and this may find applications as oxidative biomarker model.